NEHRU ARTS AND SCIENCE COLLEGE SYLLABUS UNIT

NEHRU ARTS AND SCIENCE COLLEGE

SYLLABUS

UNIT-I

Introduction to the field of textiles- classification of fibres –natural and chemical – primary and secondary characteristics of textile fibers.

UNIT-II

Manufacturing process ,properties and uses of natural fibres – cotton ,linen ,Jute , pineapple, hemp ,silk , wool, hair fibers, man-made fibres –Viscose rayon ,acetate rayon

, nylon, polyester, acrylic.

UNIT-III

Spinning –Definition ,Classification – Chemical and mechanical spinning –blending , opening, cleaning ,doubling ,carding ,combing ,drawing ,roving ,spinning.

Yarn classification – definition , classification – simple and fancy yarns , Sewing threads and its properties.

UNIT-IV

Wovens- basic weaves –plain, twill, satin.

Fancy weaves- pile, double cloth, leno, swivel, dobby and jacquard.

UNIT-V

Non-Wovens- felting, fusing, bonding ,lamination ,netting, braiding and calico,tatting and crotcheting.

DEPARTMENT OF COSTUME DESIGN AND FASHION 1


DEPARTMENT OF COSTUME DESIGN AND FASHION

STUDY MATERIAL

COURSE : I-B.SC (CDF)

SEMESTER : II

SUBJECT : FIBER TO FABRIC

UNIT : 1

SYLLABUS

Introduction to the field of Textiles – major goals – classification of fibers –

Natural & chemical – primary and secondary characteristics of textile fibers

___________________________________________________________________________

SECTION-A

1.

Textiles are classified according to their component and structure or weave.

2.

Textiles are formed by weaving, knitting, crocheting, knotting, or pressing fibers together (felt).

3.

Clothing and household textiles are aesthetically pleasing and vary in colour, design and texture.

4.

Weaving is interlacing a set of vertical threads warp and with a set of horizontal threads weft.

5.

Knitting and crocheting involve interlacing loops of yarn.

6.

Lace is made by interlocking threads together independently.

7.

Felting involves pressing a mat of fibers together, and working them together until they become tangled.

8.

Fibers are collected from the skin or bast surrounding the stem of their respective plant.

9.

Wool refers to the hair of the domestic goat or sheep or camel.

10.

Absorbency is the ability of a fibre to take up moisture.

Explain about the introduction of textile

INTRODUCTION

A textile is a flexible material comprised of a network of natural or artificial fibers often referred to as thread or yarn. Textiles are formed by weaving, knitting, crocheting, knotting, or pressing fibers together (felt).

Textiles are classified according to their component and structure or weave. Value or quality in textiles depends on several factors, such as the quality of the raw material used and the character of the yarn spun from the fibers, whether clean, smooth, fine, or coarse and whether hard, soft, or medium twisted.



Yarn, fabrics, and tools for spinning and weaving have been found among the earliest relics of human habitations. The Textile industry is a term used for industries primarily concerned with the design or manufacture of clothing as well as the distribution and use of textiles.

THE FIELD OF TEXTILE

Food, shelter and clothing are the basic needs of everyone. All clothing is made from textile and shelters are made more comfortable and attractive by the use of textiles. Everyone is surrounded by textiles from birth to death. We walk on and wear textile products; we sit on fabric covered chairs and sofas; we sleep on and under fabrics; textiles dry us or keep us; they keep us warm and product from sun, tire, and infection. Clothing and household textiles are aesthetically pleasing and vary in colour, design and texture. They are available in a variety of price ranges. .

The history of clothing and textiles attempts an objective survey of clothing and textiles throughout human history, identifying materials, tools, techniques, and influences, and the cultural significance of these items to the people who used them.

Textiles, defined as felt or spun fibers made into yarn and subsequently netted, looped, knit or woven to make fabrics, appeared in the Middle East during the late stone age.[1] From ancient times to the present day, methods of textile production have continually evolved, and the choices of textiles available have influenced how people carried their possessions, clothed themselves, and decorated their surroundings.

Yarn, fabrics, and tools for spinning and weaving have been found among the earliest relics of human habitations. Linen fabrics dating from 5000 B.C. have been discovered in

Egypt. Woolen textiles from the early Bronze Age in Scandinavia and Switzerland have also been found. Cotton has been spun and woven in India since 3000 B.C., and silk has been woven in China since at least 1000 B.C. about the 4th cent. A.D., Constantinople began to weave the raw silk imported from China.

India has a diverse and rich textile tradition. The origin of Indian textiles can be traced to the Indus valley civilization. The people of this civilization used homespun cotton for weaving their garments. Excavations at Harappa and Mohen -jo-Daro, have unearthed household items like needles made of bone and spindles made of wood, amply suggesting that homespun cotton was used to make garments.

1500 A.D. spinning was done entirely by hand. Spinning by hand was cumbersome, tedious and a very slow process indeed. Men and women too began to look around for a more satisfactory method of weaving threads together into cloth. At the beginning of the sixteenth century, a one-thread machine was invented which was a tremendous stride ahead of the old by-hand methods. It enabled the spinner to produce about seven times more yarn than by the distaff and spindle. New improvements and new inventions were gradually made, until the making of cloth was taken entirely out of the hands of the women in the homes and spinning was relegated into the realms of the "old-fashioned."



During the industrial revolution, production was mechanized with machines powered by waterwheels and engines. Sewing machines emerged in the nineteenth century. Synthetic fibers such as nylon were invented during the twentieth century. Alongside these developments were changes in the types and style of clothing worn by humans. During the

1960s, had a major influence on subsequent developments in the industry.

The textile industry has undergone significant changes in business practices in several key areas. Labor relations, trade practices, product labeling, product safety, and environmental and antipollution measures have been subjects of public scrutiny and federal legislation.

The words fabric and cloth are commonly used in textile assembly trades (such as tailoring and dressmaking) as synonyms for textile. However, there are subtle differences in these terms. Textile refers to any material made of interlacing fibres. Fabric refers to any material made through weaving, knitting, crocheting, or bonding. Cloth refers to a finished piece of fabric that can be used for a purpose such as covering a bed.

MAJOR GOALS

Textile production played a crucial part in the industrial revolution, the establishment of organized labor, and the technological development of the country. Once, textile production was simple enough that the entire process could and did take place in the home.

Now, textiles represent a complex network of interrelated industries that produce fiber, spin yarns, fabricate cloth, and dye, finish, print, and manufacture goods. A material made mainly of natural or synthetic fibers. They are found in apparel, household and commercial furnishings, vehicles, and industrial products.

Textiles have an assortment of uses, the most common of which are for clothing and containers such as bags and baskets. In the household, they are used in carpeting, upholstered furnishings, window shades, towels, covering for tables, beds, and other flat surfaces, and in art. In the workplace, they are used in industrial and scientific processes such as filtering.

Miscellaneous uses include flags, tents, nets, cleaning devices, such as handkerchiefs; transportation devices such as balloons, kites, sails, and parachutes; strengthening in composite materials such as fibre glass and industrial geotextiles, and smaller cloths are used in washing by "soaping up" the cloth and washing with it rather than using just soap.

Textiles used for industrial purposes, and chosen for characteristics other than their appearance, are commonly referred to as technical textiles. Technical textiles include textile structures for automotive applications, medical textiles (e.g. implants), geotextiles

(reinforcement of embankments), agrotextiles (textiles for crop protection), protective clothing (e.g. against heat and radiation for fire fighter clothing, against molten metals for welders, stab protection, and bullet proof vests. In all these applications stringent performance requirements must be met.



Explain about production methods of yarn?

PRODUCTION METHODS

There is a logical development of raw material into finished consumers' goods.

Studying textile materials in the interesting sequence of "fibre to yarn to fabric" will help understand the construction and ultimate qualities of the fabrics with which will become familiar. Here are the steps in the manufacture of fabrics from raw material to finished goods:

Spinning

The fabrication of yarn (thread) from either discontinuous natural fibers or bulk synthetic polymeric material. In a textile context the term spinning is applied to two different processes leading to the yarns used to make threads, cords, ropes, or woven or knitted textile products.

Weaving

Weaving is a textile production method which involves interlacing a set of vertical threads (called the warp) with a set of horizontal threads (called the weft). This is done on a machine known as a loom, of which there are a number of types. Some weaving is still done by hand, but the vast majority is mechanized

.

Knitting

Knitting and crocheting involve interlacing loops of yarn, which are formed either on a knitting needle or on a crochet hook, together in a line. The two processes are different in that knitting has several active loops at one time, on the knitting needle waiting to interlock with another loop, while crocheting never has more than one active loop on the needle.

Braiding

Braiding or plaiting involves twisting threads together into cloth. Knotting involves tying threads together and is used in making macrame.

Lace

Lace is made by interlocking threads together independently, using a backing and any of the methods described above, to create a fine fabric with open holes in the work. Lace can be made by either hand or machine.

Felting



Felting involves pressing a mat of fibers together, and working them together until they become tangled. A liquid, such as soapy water, is usually added to lubricate the fibers, and to open up the microscopic scales on strands of wool.

• Carpets, rugs, velvet, velour, and velveteen, are made by interlacing a secondary yarn through woven cloth, creating a tufted layer known as a nap or pile.

INTRODUCTIONS TO FIRBERS

Fibre, fine hair-like structure of animal, vegetable, mineral, or synthetic origin. Fibres average less than 0.05 cm (0.02 in) in diameter. Used for textiles and for many other products, fibres are classified according to their origin, their chemical structure, or both.

The first essential of a fibre is that it must be hundreds of tines longer than it is wide to enable it to be spun into a thread for weaving. It must also be strong and flexible and elastic enough to withstand the strain of the processes required producing a cloth that wears well. If the fibre is a very coarse one, it produces a cloth resembling sacking. For comfort in weaving, all fibres need to be able to absorb moisture. Luster may be desirable for appearance, and weight and flexibility can affect draping.

FIBRES

The basic unit of a textile structure is fibre. The textile industry uses many different kinds of fibres as its raw materials. Some of these fibres were known and used in the earlier years of civilization, as well as in modem times.

Fibre is a class of hair-like materials that are continuous filaments or are in discrete elongated pieces, similar to pieces of thread. They can be spun into filaments, thread, or rope.

They can be used as a component of composite materials. They can also be matted into sheets to make products such as paper or felt.

Explain the classification of fiber?

CLASSIFICATION OF FIBRES

In order to simplify the study of textile fibres, materials with similar properties must be grouped in some logical order. Each country has developed its own system for naming fibres. The two major groups, or families, of fibres specified by the act are: Natural fiber and

Man made or synthetic fiber.

Natural Fibers

The term “natural fibers” covers a broad range of vegetable, animal, and mineral fibers.



Vegetable fibers

Vegetable fibers are generally comprised mainly of cellulose: examples include cotton, linen, jute, flax, ramie, sisal, and hemp. Cellulose fibers serve in the manufacture of paper and cloth.

This fiber can be further categorized into the following:

•

Seed fiber: Fibers collected from seeds or seed cases. E.g. cotton and kapok.

• Leaf fiber: Fibers collected from leaves. E.g. sisal and agaves

.

•

Bast fiber or skin fiber : Fibers are collected from the skin or bast surrounding the stem of their respective plant. These fibers have higher tensile strength than other fibers. Therefore, these fibers are used for durable yarn, fabric, packaging, and paper. Some examples are flax, jute, kenaf, industrial hemp, ramie, rattan, soybean fiber, and even vine fibers and banana fibers.

•

Fruit fiber: Fibers are collected from the fruit of the plant, e.g. coconut (coir) fiber.





•

Stalk fiber: Fibers are actually the stalks of the plant. E.g. straws of wheat, rice, barley, and other crops including bamboo and grass. Tree wood is also such a fiber.

The most used natural fibers are cotton, flax and hemp, although sisal, jute, kenaf, and coconut are also widely used. Hemp fibers are mainly used for ropes and aerofoil because of their high suppleness and resistance within an aggressive environment. Hemp fibers are, for example, currently used as a seal within the heating and sanitary industries.

Animal fibers

Animal fibers generally comprise proteins and are commonly made from hair or fur.

•

Wool refers to the hair of the domestic goat or sheep, which is distinguished from other types of animal hair in that the individual strands are coated with scales and tightly crimped, and the wool as a whole is coated with an oil known as lanolin, which is waterproof and dirt proof. Woolen refers to a bulkier yarn produced from carded, non-parallel fibre, while worsted refers to a finer yarn which is spun from longer fibres which have been combed to be parallel. Wool is commonly used for warm clothing.

Cashmere, the hair of the Indian Cashmere goat, and mohair, the hair of the North

African Angora goat, are types of wool known for their softness. Other animal textiles which are made from hair or fur are alpaca wool, llama wool, and camel hair, generally used in the production of coats, jackets, ponchos, blankets, and other warm coverings. Angora refers to the long, thick, soft hair of the Angora rabbit.

•

Silk is an animal textile made from the fibers of the cocoon of the Chinese silkworm. This is spun into a smooth, shiny fabric prized for its sleek texture.

Mineral fibers

Mineral fibers are naturally occurring fiber or slightly modified fiber procured from minerals. These can be categorized into the following categories:

•

Asbestos and basalt fiber are used for vinyl tiles, sheeting, and adhesives, "transit" panels and siding, acoustical ceilings, stage curtains, and fire blankets.

•

Glass Fiber is used in the production of spacesuits, ironing board and mattress covers, ropes and cables, reinforcement fiber for composite materials, insect netting, flame-retardant and protective fabric, soundproof, fireproof, and insulating fibers

.

•

Metal fiber , metal foil, and metal wire have a variety of uses, including the production of cloth-of-gold and jewelry. Hardware cloth is a coarse weave of steel wire, used in construction.



Man Made fibres

Synthetic fibers are the result of extensive research by scientists to improve upon naturally occurring animal and In general, synthetic (manmade) fibers are created by forcing, usually through extrusion, fiber forming materials through holes (called spinnerets) into the air, forming a thread. Before synthetic fibrers were developed, artificial (manufactured) fibers were made from cellulose, which comes from plants.

The manufacturing process of regenerated fibres consists of bringing a natural high polymer substance into solution in a suitable way and extruding this solution through a nozzle (orifice), regenerating the same high polymer in the form of a solid filament. A regenerated fibre is one which has a different physical structure than the substance from which it is made, but is essentially the same chemically. Rayon is Regenerated Cellulose, i.e., cellulose that has gone through the manufacturing process, from solid to liquid to solid, without chemical change.

The first artificial fiber, known as artificial silk from 1855 onwards, became known as viscose around 1894, and finally rayon in 1924. A similar product known as cellulose acetate was discovered in 1865. Rayon and acetate are both artificial fibers, but not truly synthetic, being made from wood. Although these artificial fibers were discovered in the mid-nineteenth century, successful modern manufacture began much later

Nylon, the first synthetic fiber, made its debut in the United States as a replacement for silk, just in time for World War II rationing. Its novel use as a material for women's stockings overshadowed more practical uses, such as a replacement for the silk in parachutes and other military uses.

Common synthetic fibers include:

•

Polyester fiber is used in all types of clothing, either alone or blended with fibres such as cotton.

• Aramid fiber (e.g. Twaron) is used for flame-retardant clothing, cutprotection, and armor.

•

Acrylic is a fibre used to imitate wools, including cashmere, and is often used in replacement of them.

•

Nylon is a fibre used to imitate silk; it is used in the production of pantyhose. Thicker nylon fibers are used in rope and outdoor clothing.

•

Spandex (trade name Lycra) is a polyurethane fibre that stretches easily and can be made tight-fitting without impeding movement. It is used to make active wear, bras, and swimsuits.

•

Olefin fiber is a fiber used in active wear, linings, and warm clothing. Olefins are hydrophobic, allowing them to dry quickly. A sintered felt of olefin fibers is sold under the trade name Tyvek.



•

Ingeo is a polylactide fiber blended with other fibres such as cotton and used in clothing. It is more hydrophilic than most other synthetics, allowing it to wick away perspiration.

•

Lurex is a metallic fiber used in clothing embellishment.

Properties of synthetic fibres

.

They are flexible, light and very resistant. They do not absorb humidity and maintain body heat; therefore they are not suitable for the manufacture of summer articles if not mixed with other natural fibres. They do not shrink, crease and maintain machine pleating, avoiding ironing. They dye well. Due to their elasticity they are used in the manufacture of underwear, swimming costumes and sportswear

Natural fibers:

Fibers from plants or animal sources. Lower quality, short fibers are staple fibers.

Long, continuous fibers of higher quality are filament fibers.

•

Cellulosic fibers: Fibers derived from plants.

•

Protein fibers: Fibers derived from animals or insects.

Manufactured fibers :

Fibers that are man-made (synthetic) and are created by combining various substances with chemicals. Solid raw materials and chemicals are melted or dissolved to form a thick liquid. The liquid is forced through the tiny holes of a mechanical device known as a spinneret to form filaments. (This process is similar to pushing dough through a pasta machine to make spaghetti.) The filaments are then stretched, hardened, and crimped and/or cut into lengths.

• Cellulosic manufactured fibers are made from cellulose from plants such as soft wood pulp and are changed into usable fibers by applying chemicals.

• Noncellulosic manufactured fibers are made from various petrochemical mixtures of crude oil, natural gas, air, and water.

Explain the fiber properties?

FIBRE PROPERTIES

To be spinnable, a fibre must have sufficient length, pliability, strength, and cohesiveness to form a yarn. Fibres must also be inexpensive, available, and constant in supply to be economically suitable for production. To make such a fabric the manufacturer


NEHRU ARTS AND SCIENCE COLLEGE chooses fibres, yarns, weaves, and finishes with a combination of properties which will give the type of Serviceability the consumer wants.

Primary Characteristics of Textile Fibre

The primary properties of textile fibre is

• Stable length

• Tensile strength,

• Fineness,

• Spinnability, and

• Uniformity

Stable length - Staple fibres are short in length, measured in inches and range from threequartos of an inch to 18 inches in length. All the natural fibres, except silk, are staple fibres.

Any filament fibre can be cut into staple of a length determined by the end-use desire

Tensile strength - Strength of a fibre is the ability to resist strains and stresses. It is expressed as tensile strength which is measured in pounds per square inch (p.s.i.) or as tenacity which is measured in grams per denier. Some fibres gain strength when wet, some lose strength, and some are unaffected by water.

Fineness – In a fibre, the ratio or relationship if length to width or cross-sectional area is expressed as its fineness. In coarse fibres the length is about 700 times more than the width.

The ratio may be even 5000 in case of very fine fibres. Only fine fibres can produce fine yarn. Fineness does much to determine properties and characteristics of particular fibre and it also determines the end use of fibres.

Spinnability – Spinnability inclues several physical properties each having an effect on the ability of the fibres to be spun into yarn. For Example: Staple fibres must have to be capable of taking a twist. They must have a certain degree of friction against one another to stay in place when pull is applied to the yarn. And they must be able to take on hole special finishes for lubrication during spinning or to provide additional surface resistance to abrasion.

Uniformity – This means the evenness of the individual fibres in length and diameter. A fibre possessing this property can produce reasonably even threads. This is also important in connection with the strength of the resulting yarn. The more uniform the yarn the stronger the yarn.

Secondary Characteristics of Textile Fibre

The secondary properties of textile fibre is

• Crimp

• Elasticity

• Cohesion



• Density

• Plasticity

• Absorbency

• Resilience

• Capillarity or Porosity

• Colour

• Luster

• Flexibility

• Rigidity

• Abrasion resistance

• Static electric resistance

Crimp - Crimp refers to the waves or bends that occur along the length of a fibre. Wool has natural crimp. Manmade fibres may be given a permanent crimp. Fibre crimp increases cohesiveness, resiliency, and resistance to abrasion. It helps fabrics maintain their thickness.

Elasticity - Elasticity means the ability of a stretched material to return immediately to its original size.

Cohesion - Cohesiveness is the ability of fibres to cling together. This is important in staple fibres, but unimportant in filament fibres.

Density - Density and specific gravity are measured of the weight of a fiber. Density is the weight in grams per cubic centimetre. Specific gravity is the ratio of the mass of the fibre to the mass of an equal volume of water at 40°C. The weight of a fabric is determined by the density or specific gravity of the fibres.

Plasticity - Plasticity is that property of a fibre which enables the user to 'shape it semipermanently or permanently by moisture, heat, and pressure or by heat and pressure alone.

Absorbency - Absorbency is the ability of a fibre to take up moisture and is expressed as percentage of moisture regain, which is the percentage of moisture that a bone-dry fibre will absorb from the air under standard conditions of temperature and humidity. The ability of a fibre to absorb moisture is directly related to washability, dyeing, shrinkage, absorption of aqueous finishes, comfort on humid days, and soiling. Staple fibres hold more water than filament fibres since they pack less compactly and create a sponge-like condition in the yarn and fabric. For this reason staple fibre fabrics require a longer drying time.

Resilience - Resiliency is the ability of a fibre or fabric to recover, over a period of time, from deformation such as stretching, compressing, bending or twisting. A resilient fabric has good crease recovery, hence requires a minimum of ironing. Resilient fabrics also retain high bulk.

Capillarity or Porosity - This two terms express properties with the similar influence on the ability of a textile fibre or yarn to accept and hold a dye, a finish a lubricant or even resin in order to increase the wrinkle resistance of a fabric or to give it a wash and wear finish.



Liquids passed rapidly through porosity. In the case of the passage of these liquids through the hollow centre or lumen in cotton or through small voids on the surface of wool fibre. It is usually regarded as the effect of the mechanism capillarity.

Colour – Most natural fibre have some colour. The synthetic fibres too have a slight creamy or yellow colour.

For Example:

Silk is yellow to tan

Wool is brownish tint

Cotton is a creamy white or brown

Luster - Lustre is the shine, sheen or brightness of a fibre caused by reflection of light.

Smooth fibres reflect more light than rough or serrated fibres; round fibres reflect more light than flat fibres. Filaments which are laid together with little or no twist reflect more light than short fibres which must be twisted together to forth yarns. Manmade fibres can be delustered by adding oil or pigments to the solution from which the fibre is spun.

Flexibility - Pliability or flexibility is the ease of bending or shaping. Pliable fibres are easily twisted to make yarns. They make fabrics that resist splitting when folded or creases many times in the same place.

Rigidity - Stiffness or rigidity is the opposite of flexibility. It is the resistance to bending or creasing. Rigidity and weight together make up the body of the fabric.

Abrasion resistance - Abrasion resistance is the ability of a fibre to withstand the rubbing or abrasion it gets in everyday use. Inherent toughness, natural pliability, and smooth filament surface are fibre characteristics that contribute to abrasion resistance.

Static electric resistance - Phenomenon of static electricity creates a problem in the spinning and other processing of textile fibres especially in rooms with very low relative humidity. The problem is much more severe in the case of synthetic fibres which have extremely low electrical conductivity and generally absorb too little moisture to provide a path where y the static electricity can be carried away. Static electrical properties create problems in the packaging and in the sewing

Other Characteristics of Textile Fibre

• Wicking or wetting

• Chemical resistance

• Resistance to moths, and mildew

• Flammability or inflammability

Wicking or wetting - Wicking or wetting refers to the conduction of moisture along the fibre or through the fabric, although the fibre itself does not absorb much moisture. This property is related to surface wetting and is not the same as absorbency

.



Chemical resistance - The chemical reactivity of each fibre depends on the arrangement of the elements in the molecule and the reactive groups it contains. Dry-cleaning solvents, perspiration, soap, synthetic detergents, bleaches, atmospheric gas, soot, and sunshine may all cause chemical degradation on some or all of the fibres.

Resistance to moths, and mildew - Resistance to moths, and mildew is due to the chemical composition of the fibre. These properties are important to the consumer because they indicate the type of care needed during storage as well as during use. Fibres without natural resistance must have protective finishes added or have their chemical composition changed to make them resistant.

Flammability or inflammability - Flammability or inflammability refers to the ease of ignition and the speed and length of burning. Non-flammable fibres will not burn.

Flammability depends not only on the chemical composition but on the air incorporated in the yarn or fabric. Combustible finishes or dyes may take a non-flammable fibre burn.

Finishes can also be added to make fibres nonflammable.

SUGGESTED QUESTIONS

1.

Explain the classification of fibres.

2. Explain briefly about the essential and desirable properties of fiber.




STUDY MATERIAL

COURSE : I-B.SC (CDF)

SEMESTER : II

SUBJECT : FIBER TO FABRIC

UNIT : 2

SYLLABUS

Manufacturing process, properties and uses of natural fibers –cotton, linen, jute, pineapple, hemp, silk, wool, hair fibers, Man-made fibers – viscose rayon, acetate rayon, nylon, polyester, acrylic

________________________________________________________________

SECTION-A

1.

Cotton is a fibre that grows from the surface of seeds in the pods, or bolls, of a bushy mallow plant.

2.

The cotton plant belongs to the genus Gossypium of the family Malvaceae.

3.

Linen yarn is spun from the long fibers found just behind the bark in the multilayer stem of the flax plant.

4.

Jute is a long, soft, shiny vegetable fibre that can be spun into coarse, strong threads .

5.

Sheep are sheared once a year usually in the springtime.

INTRODUCTION

Fibers are the raw materials for all fabrics. Some fibers occur in nature as fine strands that can be twisted into yarns. These natural fibers come from plants, animals, and minerals.

For most of history, people had only natural fibers to use in making cloth.

The use of natural fibers extends back beyond recorded history with archaeological evidence indicating that wool and flax were being woven into fabrics by the sixth century

BC.

Explain about cotton?



COTTON

The seed of plant is often attached to hairs which are constructed in the main from cellulose. Many of these fibres are used in the textile industry, on of themcotton- has become the most important textile fibre in the world.

Cotton is a fibre that grows from the surface of seeds in the pods, or bolls, of a bushy mallow plant. Each fibre is a single elongated cell that is flat, twisted, and ribbonlike with a wide inner hollow (lumen). It is composed of about 90% cellulose and about 6% moisture; the remainder consists of natural impurities. The outer surface of the fibre is covered with a protective waxlike coating, which gives the fibre a somewhat adhesive quality. This characteristic combined with its natural twist contributes to making cotton an excellent fibre for spinning into yarn. Cotton yam is used to make fabrics that are universally used for all types of apparel, home furnishings, and industrial applications.

In common with other natural fibres, cotton is available in a great variety of fibre qualities, which are determined particularly according to fibre length and fibre fineness. The

West Indies produces a small quantity of cotton compared with world production, but its supreme excellence is well known and it is commonly known as Sea Island. Its length of about 6cm. (which is very long for cotton), lustre, fineness, and accompanying softness make it suitable for fine, best quality yarns and fabrics. A very short, coarse cotton which is only suitable for coarse yarns and fabrics could be, for instance, an Indian cotton known as

Bengals.

Types of Cotton

Raw cotton is creamy white in colour.The cotton of commerce can be classified into three general groups on basic of fibre length, fibre fineness, and geographical region

(country) of growth as follows:

Type 1 Long, fine cotton -Long staple, fine strong fibre of good lustre, which form the top

quality cotton. The fibres are generally of 115 microns diameter,



staple length from 1 to 2W. It includes Sea Island, American and

Egyptian cotton. They are not easy to grow, they are expensive and

Are used only for high quality, fine cloths, and hosiery yarns.

Type 2 Standard cotton -Intermediate staple, coarser texture and charter length. The fibres

are generally of 12-17 microns diameter, from 1 to 1 5/16". The

principal member of this group is American Upland . They are used

far standard fabrics.

Type 3 Coarse, shorter cotton -Short staple, waiter fibres of no lustre and low in strength that

range in staple length from 3/8 to 1". The fibres are generally of

13-22 microns diameter. These are the Indian or Asiatic cottons. It

is used for lower quality fabrics (sometimes blended with wool, far

cotton blankets and carpets).

The Cotton Plant

The cotton plant belongs to the genus Gossypium of the family Malvaceae (mallow family). It is generally a shrubby plant having broad three-lobed leaves and seeds in capsules, or bolls; each seed is surrounded with downy fiber, white or creamy in color and easily spun.

The fibers flatten and twist naturally as they dry.

Cotton is of tropical origin but is most successfully cultivated in temperate climates with well-distributed rainfall. The requisites on the basis of which to judge the quality of the cotton are the grade, the colour, and the length of the fibres and the character.

The Production Process

1. In spring, the acreage is cleared for planting. Mechanical cultivators rip out weeds and

grass that may compete with the cotton for soil nutrients, sunlight, and water, and may

attract pests that harm cotton. The land is plowed under and soil is broken up and formed

into rows.

2. Cottonseed is mechanically planted by machines that plant up to 12 rows at a time. The

planter opens a small furrow in each row, drops in seed, covers them, and then packs more

dirt on top. Seed may be deposited in either small clumps (referred to as hill-dropped) or

singularly (called drilled). The seed is placed 0.75 to 1.25 in (1.9 to 3.2 cm) deep,



depending on the climate. The seed must be placed more shallowly in dusty, cool

areas of the Cotton Belt, and more deeply in warmer areas.

3. With good soil moisture and warm temperature at planting, seedlings usually emerge five

to seven days after planting, with a full stand of cotton appearing after about 11 days.

Occasionally disease sets in, delaying the seedlings' appearance. Also, a soil crust may

Prevent seedlings from surfacing. Thus, the crust must be carefully broken by machines or

irrigation to permit the plants to emerge.

4. Approximately six weeks after seedlings appear, "squares," or flower buds, begin to form.

The buds mature for three weeks and then blossom into creamy yellow flowers, which turn

pink, then red, and then fall off just three days after blossoming. After the flower falls

away, a tiny ovary is left on the cotton plant. This ovary ripens and enlarges into a green

pod called a cotton boll.

5. The boll matures in a period that ranges from 55 to 80 days. During this time, the football-

shaped boll grows and moist fibers push the newly formed seeds outward. As the boll

ripens, it remains green. Fibers continue to expand under the warm sun, with each fiber

growing to its full length about 2.5 in (6.4 cm)during three weeks. For nearly six weeks,

the fibers get thicker and layers of cellulose build up the cell walls. Ten weeks after

flowers first appeared, fibers split the boll apart, and cream colored cotton pushes forth.

The moist fibers dry in the sun and the fiber collapse and twist together, looking like

ribbon. Each boll contains three to five "cells," each having about seven seeds embedded

in the fiber.





The domestics market -sheets and towels- is dominated by cotton. Most sheets and pillowcases are blends of cotton and polyester, but 100% cotton sheets are available once again. Polyester is occasionally blended with cotton in towels to provide strength and durability to the base fabric, but the surface pile remains cotton for absorbency.

INTRODUCTION OF VEGTABLES

Vegetable fibers are generally comprised mainly of cellulose: examples include cotton, linen, jute, flax, ramie, sisal, and hemp. Cellulose fibers serve in the manufacture of paper and cloth.

The numerous varieties of bast fibres are used for purposes ranging from weaving fine textiles to manufacturing cordage. Linen cloth is made from flax, and coarser cloths and rope and twine are produced from hemp, jute, and ramie. Vascular fibres are used almost entirely for cordage making. They include agave (sisal), henequen, Manila hemp, yucca, and a number of others. The vascular fibres of the pineapple have been used in the production of textiles

.

Explain about linen?

LINEN

Linen yarn is spun from the long fibers found just behind the bark in the multilayer stem of the flax plant (Linum usitatissimum). In order to retrieve the fibers from the plant, the woody stem and the inner pith (called pectin), which holds the fibers together in a clump, must be rotted away. The cellulose fiber from the stem is spinnable and is used in the production of linen thread, cordage, and twine. From linen thread or yarn, fine toweling and dress fabrics may be woven. Linen fabric is a popular choice for warm-weather clothing. It feels cool in the summer but appears crisp and fresh even in hot weather. Household linens truly made of linen become more supple and soft to the touch with use; thus, linen was once the bed sheet of choice.

Raw Materials

All that is needed to turn flax fiber into linen, and then spin and weave the linen fibers into linen fabric is the cellulose flax fiber from the stem of the flax plant. The process for separating the fibers from the woody stalk can use either water or chemicals, but these are ultimately washed away and are not part of the finished material.

The Manufacturing Process

1.

Cultivating

• It takes about 100 days from seed planting to harvesting of the flax plant. Flax cannot endure very hot weather; thus, in many countries, the planting of seed is figured from the


NEHRU ARTS AND SCIENCE COLLEGE date or time of year in which the flax must be harvested due to heat and the growers count back 100 days to determine a date for planting. In some areas of the world, flax is sown in winter because of heat in early spring. In commercial production, the land is plowed in the spring then worked into a good seedbed by dicing, harrowing, and rolling. Flax seeds must be shallowly planted. Seeds may be broadcast by hand, but the seed must be covered over with soil. Machines may also plant the seed in rows.

• Flax plants are poor competitors with weeds. Weeds reduce fiber yields and increase the difficulty in harvesting the plant. Tillage of the soil reduces weeds as do herbicides. When the flax plants are just a few inches high, the area must be carefully weeded so as not to disturb the delicate sprouts. In three months, the plants are straight, slender stalks that may be

2-4 ft (61- 122 cm) in height with small blue or white fibers. (Flax plants with blue flowers yield the finest linen fibers.)

2.

Harvesting

• After about 90 days, the leaves wither the stem turns yellow and the seeds turn brown, indicating it is time to harvest the plant. The plant must be pulled as soon as it appears brown as any delay results in linen without the prized luster. It is imperative that the stalk not be cut in the harvesting process but removed from the ground intact; if the stalk is cut the sap is lost, and this affects the quality of the linen. These plants are often pulled out of the ground by hand, grasped just under the seed heads and gently tugged. The tapered ends of the stalk must be preserved so that a smooth yarn may be spun. These stalks are tied in bundles called beets and are ready for extraction of the flax fiber in the stalk. However, fairly efficient machines can pull the plants from the ground as well.

3.

Releasing the Fiber from the stalk

• The plant is passed through coarse combs, which removes the seeds and leaves from the plant. This process, called rippling, is mechanized in many of the flax-producing countries.

• The woody bark surrounding the flax fiber is decomposed by water or chemical retting, which loosens the pectin or gum that attaches the fiber to the stem. If flax is not fully retted, the stalk of the plant cannot be separated from the fiber without injuring the delicate fiber.

Thus, retting has to be carefully executed. Too little retting may not permit the fiber to be separated from the stalk with ease. Too much retting or rotting will weaken fibers.

• Retting may be accomplished in a variety of ways. In some parts of the world, linen is still retted by hand, using moisture to rot away the bark. The stalks are spread on dewy slopes, submerged in stagnant pools of water, or placed in running streams. Workers must wait for the water to begin rotting or fermenting the stem sometimes more than a week or two.

However, most manufacturers use chemicals for retting. The plants are placed in a solution either of alkali or oxalic acid, then pressurized and boiled. This method is easy to monitor and rather quick, although some believe that chemical retting adversely affects the color and strength of the fiber and hand retting produces the finest linen. Vat or mechanical retting requires that the stalks be submerged in vats of warm water, hastening the decomposition of


NEHRU ARTS AND SCIENCE COLLEGE the stem. The flax is then removed from the vats and passed between rollers to crush the bark as clean water flushes away the pectin and other impurities.

• After the retting process, the flax plants are squeezed and allowed to dry out before they undergo the process called breaking. In order to crush the decomposed stalks, they are sent through fluted rollers which break up the stem and separate the exterior fibers from the bast that will be used to make linen. This process breaks the stalk into small pieces of bark called shives. Then, the shives are scutched. The scutching machine removes the broken shives with rotating paddles, finally releasing the flax fiber from stalk.

• The fibers are now combed and straightened in preparation for spinning. This separates the short fibers (called tow and used for making coarser, sturdy goods) from the longer and more luxurious linen fibers. The very finest flax fibers are called line or dressed flax, and the fibers may be anywhere from 12-20 in (30.5-51 cm) in length.

4.

Spinning

• Line fibers (long linen fibers) are put through machines called spreaders, which combine fibers of the same length, laying the fibers parallel so that the ends overlap, creating a sliver.

The sliver passes through a set of rollers, making a roving which is ready to spin.

• The linen roving, resembling tresses of blonde hair, are put on a spinning frame and drawn out into thread and ultimately wound on bobbins or spools. Many such spools are filled on a spinning frame at the same time. The fibers are formed into a continuous ribbon by being pressed between rollers and combed over fine pins. This operation constantly pulls and elongates the ribbon-like linen until it is given its final twist for strength and wound on the bobbin. While linen is a strong fiber, it is rather inelastic. Thus, the atmosphere within the spinning factory must be both humid and warm in order to render the fiber easier to work into yarn. In this hot, humid factory the linen is wet spun in which the roving is run through a hot water bath in order to bind the fibers together thus creating a fine yarn. Dry spinning does not use moisture for spinning. This produces rough, uneven yarns that are used for making inexpensive twines or coarse yarns.

• These moist yarns are transferred from bobbins on the spinning frame to large take-up reels.

These linen reels are taken to dryers, and when the yarn is dry, it is wound onto bobbins for weaving or wound into yarn spools of varying weight. The standard measure of flax yarn is the cut. It is based on the measure of 1 lb (453.59 g) of flax spun to make 300 yd (274.2 m) of yarn being equal to one cut. If 1 lb (453.59 g) of flax is spun into 600 yd (548.4 m), then it is a "no. 2 cut." The higher the cut, the finer the yarn becomes. The yarn now awaits transport to the loom for weaving into fabrics, toweling, or for use as twine or rope.

Physical and Chemical Properties of Flax

1 Strength



Flax is one of the strongest fibres. It is especially durable being two to three times as strong as cotton. On the natural fibres, it is second in strength to silk. In linen, weight may be considered a criterion of durability. Flax also increases about 20% in strength when wet.

2.

Elasticity

Linen has no significant elasticity. It is the least elastic of natural fibres. In order to fit comfortably, linen garments should neither bind nor pull at the seams.

3 Resilience

Linen is relatively stiff and has little resilience. Therefore, it wrinkles easily, which somewhat offsets its otherwise excellent qualities as a fabric for summer apparel. Due to its stiffness, linen fabrics should not have creases pressed firmly into them.

4 Absorbency

When absorbency is the main consideration, linen is preferable to cotton. It absorbs moisture and dries more quickly. This fabric takes up water rapidly. It has very good wicking properties. This makes the fibre comfortable to wear but difficult to dye and finish. It is therefore excellent for handkerchiefs and towels.

5 Density

Flax is one of the heavier cellulosic fibres with a density of 1.5 g/cc.

6 Luster

Flax has a silky luster due to the natural waxes found in the fibre. If this wax is removed by chemicals or solvents, the fibre becomes brittle and harsh.

7 Effect of Light

Flax has good resistance to sunlight. Max is more resistant to light than cotton, but it will gradually deteriorate from exposure.

8 Effect of Heat

Linen scorches and flames in a manner similar to cotton. Linen may be safely ironed at 204°C (400').

9 Drapability

Linen has more body than cotton and drapes somewhat better.

10 Resistance to Mildew



Dry linen has good resistance to mildew, but fabrics stored in a warm, humid atmosphere support the rapid growth of the fungus. Most insects do not damage linen. It is more resistant to attack by insects and micro organisms.

11 Heat Conductivity

Linen is most suitable for summer apparel, as it allows the heat of the body to escape.

12 Cleanliness and Washability

Linen launders well and gives up stains readily. Some linen apparel requires dry cleaning because of construction and fabric finish. Care label instructions should be observed.

13 Shrinkage

Linen does not shrink a great deal; in fact, it shrinks less than cotton. But pre shrinkage finishing is desirable.

14 Reaction to Alkalis

Linen, like cotton, is highly resistant to alkalis. Linen may also be mercerized.

15 Reaction to Acids

Linen is damaged by hot dilute acids and cold concentrated acids.

16 Affinity for Dyes

Linen does not have good affinity for dyes. However, it is possible to obtain dyes linen that has good colourfastness. When buying coloured linens, look for the words

"Guaranteed Fast Colour" on the label or get a guarantee of colourfastness from the store.

17 Resistance to Perspiration

Acid perspiration will deteriorate linen. Alkali perspiration will not cause deterioration. But in either case discolouration may occur.

Uses

Over the past 30 years the end use for linen has changed dramatically. Approximately

70% of linen production in the 1990s was for apparel textiles whereas in the 1970s only about 5% was used for fashion fabrics. Linen uses range from bed and bath fabrics (table cloths, dish towels, bed sheets, etc.), home and commercial furnishing items (wallpaper/wall coverings, upholstery, window treatments, etc.), apparel items (suits, dresses, skirts, shirts,


NEHRU ARTS AND SCIENCE COLLEGE etc.), to industrial products (luggage, canvases, sewing thread, etc.). It was once the preferred yarn for hand sewing the uppers of moccasin-style shoes (loafers), but its use has been replaced by synthetics. A linen handkerchief, pressed and folded to display the corners, was a standard decoration of a well-dressed man's suit during most of the first part of the 20 th century. Currently researchers are working on a cotton/flax blend to create new yarns which will improve the feel of denim during hot and humid weather.

Explain about jute?

JUTE

Jute is a long, soft, shiny vegetable fibre that can be spun into coarse, strong threads.

It is produced from plants in the genus Corchorus, family Malvaceae. Jute is one of the cheapest natural fibres and is second only to cotton in amount produced and variety of uses.

Jute fibres are composed primarily of the plant materials cellulose (major component of plant fibre) and lignin (major components wood fibre). It is thus a ligno-cellulosic fibre that is partially a textile fibre and partially wood. It falls into the bast fibre category

Cultivation

To grow jute, farmers scatter the seeds on cultivated soil. When the plants are about

15-20 cm tall, they are thinned out. About four months after planting, harvesting begins. The plants are usually harvested after they flower, but before the flowers go to seed. The stalks are cut off close to the ground. The stalks are tied into bundles and soaked in water (retting) for about 20 days. This process softens the tissues and breaks the hard pectin bond between the bast & Jute hurd (inner woody fiber stick) and the process permits the fibres to be separated. The fibres are then stripped from the stalks in long strands and washed in clear, running water. Then they are hung up or spread on thatched roofs to dry. After 2-3 days of drying, the fibres are tied into bundles.

The suitable climate for growing jute is a warm and wet climate, which is offered by the monsoon climate during the fall season, immediately followed by summer. Temperatures ranging from 70-100 ÂºF and relative humidity of 70%-80% are favorable for successful cultivation. Jute requires 2"-3" of rainfall weekly with extra needed during the sowing period.

Retting

Retting is the process of extracting fiber from the stem or bast of the bast fiber plants.

The available retting processes are: mechanical retting (hammering), chemical retting

(boiling & applying chemicals), steam/vapor/dew retting, and water or microbial retting.

Among them, the water or microbial retting is a century old but the most popular process in extracting fine bast fibers. However, selection of these retting processes depends on the availability of water and the cost of retting process.



To extract fine fibers from jute plant, a small stalk is harvested for pre-retting.

Usually, this small stalk is brought before 2 weeks of harvesting time. If the fiber can easily be removed form the Jute hurd or core, then the crop is ready for harvesting.

After harvesting, the jute stalks are tied into bundles and submerged in soft running water. The stalk stays submerged in water for 20 days. However, the retting process may require less time if the quality of the jute is better. In most cases, the fiber extraction process of bast fibers in water retting is done by the farmers while standing under water.

When the jute stalk is well retted, the stalk is grabbed in bundles and hit with a long wooden hammer to make the fiber loose from the jute hurd or core. After loosing the fiber, the fiber is washed with water and squeezed for dehydration. The extracted fibers is further washed with fresh water and allowed to dry on bamboo poles.

Properties of Jute

Good quality jute is coloured yellowish-white and silver-gray and has a lustrous appearance. Jute is usually brownish or greenish and has a unique lustre. The individual cells in jute are shorter than those of any of the other bast fibres. Jute is the weakest of the cellulose fibres when dry and must therefore be spun into coarse yarns.

The average strength of jute is about 3.5 gm/denier. Resiliency is poor, and fabrics do not return to shape after deformation without treatment such as washing and ironing. Jute has low sunlight resistance and poor colour fastness. It is also brittle and subject to splitting and snagging. It is readily damaged by the action of weather, moisture and abrasion.

Jute can not be bleached white since disintegrates in strong bleaches; hence it is most often used in its natural colour. Chemical finishes can be used to overcome the natural odor of jute and to make it softer. Jute is similar to other cellulosic fibres in its reactions to heat and chemicals.

Uses

Jute is the second most important vegetable fibre after cotton; not only for cultivation, but also for various uses. Jute is used chiefly to make cloth for wrapping bales of raw cotton, and to make sacks and coarse cloth. The fibres are also woven into curtains, chair coverings, carpets, area rugs, hessian cloth, and backing for linoleum.

PINEAPPLE

The fibre form the leaf of the pineapple frequently is labeled `spina". Most of the commercial fibre comes from the Philippines. It is between 5 and 10 cm. (2 to 4") in length and is lustrous and strong. Fabrics range in hand from crisp to very soft. Delicately embroidered clothing and accessories are often made of pins, it is also a cordage fibre.

Properties and uses of pina



This natured fibre is white and specially soft and lustrous. In the Philippine Islands, it is woven into pins cloth, which is soft, durable and resistant to moisture.

It is used far ship cables, power transmission cables and driving cables. Light coloured fibers are spun into coarser cloth thread, which are used for clothes and bags. Fine fibres are used for malting interior fabrics. It is also used as a material for summer hats, brushes and paper malting material.

HEMP

The fiber is one of the most valuable parts of the hemp plant. It is commonly called

"bast", meaning it grows as a stalk from the ground. Hemp fibers can be 3 to 15 feet long, running the length of the plant. Depending on the processing used to remove the fiber from the stem, the hemp naturally may be creamy white, brown, gray, black or green.

Flow chart for hemp



Harvesting

Smallholder plots are usually harvested by hand. The plants are cut at 2 to 3 cm above the soil and left on the ground to dry. Mechanical harvesting is now common, using specially adapted cutter-binders or simpler cutters.

The cut hemp is laid in swathes to dry for up to four days. This was traditionally followed by retting, either water retting (the bundled hemp floats in water) or dew retting (the hemp remains on the ground and is affected by the moisture in dew moisture, and by molds and bacterial action). Modern processes use steam and machinery to separate the fibre, a process known as thermo-mechanical pulping.

Properties

Characteristics of hemp fibre are its superior strength and durability, resistance to ultraviolet light and mold, comfort and good absorbency (8%). Hemp rope is notorious for breaking due to rot as the capillary effect of the rope-woven fibres tended to hold liquid at the interior, while seemingly dry from the outside. Hemp rope used in the age of sailing-ships was protected by tarring

Uses

Hemp is used for a wide variety of purposes, including the manufacture of cordage of varying tensile strength, clothing, and nutritional products. The bast fibers are can be used in

100% hemp products, but are commonly blended with fabrics such as linen, cotton or silk, for apparel and furnishings, most commonly a 55/45 Hemp/Cotton blend.

Explain about animal fiber?

ANIMAL FIBER

Animal fibers are natural fibers that consist largely of particular proteins. Instances are silk, hair/fur (including wool) and feathers. The most commonly used type of animal fiber is hair.

Not all animal fibers have the same properties. Alpaca fiber is known for its softness, and silk for its sheen and strength. Even within a species the fiber is not consistent. Merino is very soft, fine wool, while Cotswold is coarser, and yet both merino and Cotswold are types of sheep. This comparison can be continued on the microscopic level, comparing the diameter and structure of the fiber.

SILK

Silk is a "natural" protein fiber, some forms of which can be woven into textiles. A fine lustrous fiber composed mainly of fibroin and produced by certain insect larvae to form


NEHRU ARTS AND SCIENCE COLLEGE cocoons, especially the strong, elastic, fibrous secretion of silkworms used to make thread and fabric

Silk is often referred to as "the queen of the fibres. The shimmering appearance for which silk is prized comes from the fibres' triangular prism-like structure which allows silk cloth to refract incoming light at different angles. Silk is also the strongest natural fiber known to man

Life cycle of silkworms

The life cycle of the silk worm begins with eggs laid by the adult moth. The larvae emerge from the eggs and feed on mulberry leaves. In the larval stage, the worm is the caterpillar known as the silkworm. The silkworm spins a protective cocoon around itself so it can safely transform into a chrysalis. In nature, the chrysalis breaks through the cocoon and


NEHRU ARTS AND SCIENCE COLLEGE emerges as a moth. The moths mate and the female lays 300 to 400 eggs. A few days after emerging from the cocoon, the moths die and the life cycle continues. The cultivation of silkworms for the purpose of producing silk is called sericulture.

Sericulture

Breeding silkworms

• Only the healthiest moths are used for breeding. Their eggs are categorized, graded, and meticulously tested for infection. Unhealthy eggs are burned. The healthiest eggs may be placed in cold storage until they are ready to be hatched. Once the eggs are incubated, they usually hatch within seven days. They emerge at a mere one-eighth of an inch (3.2 mm) long and must be maintained in a carefully controlled environment. Under normal conditions, the eggs would hatch once a year in the spring when mulberry trees begin to leaf. But with the intervention of Seri culturists, breeding can occur as many as three times per year

.

Feeding the larva

• The silkworms feed only on the leaves of the mulberry tree. The mulberry leaves are finely chopped and fed to the voracious silkworms every few hours for 20 to 35 days. During this period the worms increase in size to about 3.5 inches (8.9 cm). They also shed their skin, or molt, four times and change color from gray to a translucent pinkish color.

Spinning the cocoon

• When the silkworm starts to fidget and toss its head back and forth, it is preparing to spin its cocoon. The caterpillar attaches itself to either a twig or rack for support. As the worm twists its head, it spins a double strand of fiber in a figure-eight pattern and constructs a symmetrical wall around itself. The filament is secreted from each of two glands called the spinneret located under the jaws of the silkworm. The insoluble protein-like fiber is called fibroin.

• The fibroin is held together by sericin, a soluble gum secreted by the worm, which hardens as soon as it is exposed to air. The result is the raw silk fiber, called the bave. The caterpillar spins a cocoon encasing itself completely. It can then safely transform into the chrysalis, which is the pupa stage.

Stoving the chrysalis

• The natural course would be for the chrysalis to break through the protective cocoon and emerge as a moth. However, sericulturists must destroy the chrysalis so that it does not break the silk filament. This is done by stoving, or stifling, the chrysalis with heat.

The Filature

Sorting and softening the cocoons



• The filature is the factory in which the cocoons are processed into silk thread. In the filature the cocoons are sorted by various characteristics, including color and size, so that the finished product can be of uniform quality. The cocoons must then be soaked in hot water to loosen the sericin. Although the silk is about 20% sericin, only 1% is removed at this stage. This way the gum facilitates the following stage in which the filaments are combined to form silk thread, or yarn.

Reeling the filament

• Reeling may be achieved manually or automatically. The cocoon is brushed to locate the end of the fiber. It is threaded through a porcelain eyelet, and the fiber is reeled onto a wheel.

Meanwhile, diligent operators check for flaws in the filaments as they are being reeled.

• As each filament is nearly finished being reeled, a new fiber is twisted onto it, thereby forming one long, continuous thread. Sericin contributes to the adhesion of the fibers to each other.

Packaging the skeins

• The end product, the raw silk filaments, is reeled into skeins. These skeins are packaged into bundles weighing 5-10 pounds (2-4 kg), called books. The books are further packaged into bales of 133 pounds (60 kg) and transported to manufacturing centers.

Forming silk yarn

• Silk thread, also called yarn, is formed by throwing, or twisting, the reeled silk. First the skeins of raw silk are categorized by color, size, and quantity. Next they are soaked in warm water mixed with oil or soap to soften the sericin. The silk is then dried.

• As the silk filaments are reeled onto bobbins, they are twisted in a particular manner to achieve a certain texture of yarn. For instance, "singles" consist of several filaments which are twisted together in one direction. They are turned tightly for sheer fabrics and loosely for thicker fabrics. Combinations of singles and untwisted fibers may be twisted together in certain patterns to achieve desired textures of fabrics such as crepe de chine, voile, or tram.

Fibersmay also be manufactured in different patterns for use in the nap of fabrics, for the outside, or for the inside of the fabric.

• The silk yarn is put through rollers to make the width more uniform. The yarn is inspected, weighed, and packaged. Finally, the yarn is shipped to fabric manufacturers.

Degumming thrown yarn

• To achieve the distinctive softness and shine of silk, the remaining sericin must be removed from the yarn by soaking it in warm soapy water. Degumming decreases the weight of the yarn by as much as 25%.



Finishing silk fabrics (weighting)

• After degumming, the silk yarn is a creamy white color. It may next be dyed as yarn, or after the yarn has been woven into fabric. The silk industry makes a distinction between pure-dye silk and what is called weighted silk. In the puredye process, the silk is colored with dye, and may be finished with water-soluble substances such as starch, glue, sugar, or gelatin. To produce weighted silk, metallic substances are added to the fabric during the dying process. This is done to increase the weight lost during degumming and to add body to the fabric. If weighting is not executed properly, it can decrease the longevity of the fabric, so pure-dye silk is considered the superior product. After dyeing, silk fabric may be finished by additional processes, such as bleaching, embossing, steaming, or stiffening.

Kinds of Silk

Silk refers to cultivated silk

1.

Wild or Tussah Silk

The silkworms that hatch from a wild species of moth live on oak leaves instead of mulberry leaves that form the food of the cultivated species. This coarser food produces an irregular and coarse filament that is hard to bleach and hard to dye. The tannin in the oak leaves gives wild sill: its tan colour. Wild silk is less lustrous than cultivated sills, as only a low percentage (about 11%) of sericin is removed in the degumming process. Wild silk fabrics are durable and have a coarse, irregular surface. They are washable and are generally less expensive than pure-dye silk.

2.

Doupion Silk

Doupion silk comes from two silkworms that spin their cocoons together. The yarn is uneven, irregular, and large in diameter.

3.

Raw Silk

Raw silk refers to cultivated silk-in-the-gum. Raw silk varies in colour from graywhite to canary yellow but since the colour is in the sericin, boiled-off silk is white.

4. Reeled Silk

Reeled silk is the long continuous filament, 300 to 1600 yards in length.

5.

Spun Silk

Spun silk refers to yarns made from silk from pierced cocoons and waste silk.



6.

Waste Silk

Waste silk is comprised of the tangled mass of silk on the outside of the cocoon and the fibre from pierced cocoons

.

Major fiber properties

Physical properties

1.

Shape

Silk has a triangular shaped cross section whose corners are rounded.

1. Luster

Due to the triangular shape (allowing light to hit it at many different angles), silk is a bright fiber meaning it has a natural shine to it.

2. Covering power

Silk fibers have poor covering power. This is caused by their thin filament form.

3. Hand

When held, silk has a smooth, soft texture that, unlike many synthetic fibers, is not slippery.

4. Denier

4.5 g/d (dry) Â; 2.8-4.0 g/d (wet)

Mechanical properties

(1) Strength

Silk is the strongest of all the natural fibers; however it does lose up to 20% of its strength when wet.

(2) Elongation/elasticity

Silk has moderate to poor elasticity. If elongated even a small amount the fibers will remain stretched.



(3) Resiliency

Silk has moderate wrinkle resistance

Chemical Properties

1. Protein Composition

Silk is made up of GLY-SER-GLY-ALA-GLY and forms Beta pleated sheets.

Interchaine H-bonds are formed while side chains are above and below the plane of the Hbond network. Small residue (Gly) allows tight packing and the fibers are strong and resistant to stretching. The tension is due to covalent peptide bonds. Since the protein forms a Beta sheet, when stretched the force is applied to these strong bonds and they do not break. The

50% GLy composition means that Gly exists regularly at every other position.

2. Absorbency

Silk has a good moisture regain of 11%.

3. Electrical conductivity

Silk is a poor conductor of electricity making it comfortable to wear in cool weather.

This also means however, that silk is susceptible to static cling.

4. Resistance to ultraviolet light/biological organisms

Silk can become weakened if exposed to too much sunlight. Silk may also be attacked by insects, especially if left dirty.

5. Chemical reactivity/resistance

Silk is resistant to mineral acids. It is yellowed by perspiration and will dissolve in sulphuric acid.

Other properties

1.

Dimensional stability

Unwashed silk chiffon may shrink up to 8% due to a relaxation of the fiber macrostructure. So silk should either be prewashed prior to garment construction, or dry cleaned. However, dry cleaning may still shrink the chiffon up to 4%.

Occasionally, this shrinkage can be reversed by a gentle steaming with a press cloth.

Gradual shrinkage is virtually nonexistent, as is shrinkage due to molecular-level deformation.



End Uses

Silk is used for luxury apparel, household textiles. It is popular in men's neckties for its hand and drape. Silk apparel fabrics are available in a wide range of weights and constructions. The fibre is used alone and in blends with other fibres.

Silk is used in fine drapery and upholstery fabrics. Some of the most expensive handmade oriental rugs are made of silk fibres. Protection from sunlight damage may be provided by careful lining of draperies and the positioning of furniture so that the silk upholstorv is not a direct sunlight. Very fine silk filaments are used in eye surgery.

Silk sutures still are used by some surgeons. The protein fibre is believed by some to be more compatible with human tissue than sutures of other materials.

WOOL

Wool is the fiber derived from the fur of animals of the Caprinae family; principally sheep.Wool was probably the first animal fiber to be made into cloth. The art of spinning wool into yarn developed about 4000 B.C.

No one knows when man started using wool as a textile fibre. The dense, soft, often curly hair forming the coat of sheep and certain other mammals, such as the goat and alpaca, consisting of cylindrical fibers of keratin covered by minute overlapping scales and much valued as a textile fabric.

5.3.1 Raw Materials

In scientific terms, wool is considered to be a protein called keratin. Its length usually ranges from 1.5 to 15 inches (3.8 to 38 centimeters) depending on the breed of sheep. Each piece is made up of three essential components: the cuticle, the cortex, and the medulla.

The cuticle is the outer layer. It is a protective layer of scales arranged like shingles or fish scales. When two fibers come in contact with each other, these scales tend to cling and stick to each other. It's this physical clinging and sticking that allows wool fibers to be spun into thread so easily.

The cortex is the inner structure made up of millions of cigar-shaped cortical cells. In natural-colored wool, these cells contain melanin. The arrangement of these cells is also responsible for the natural crimp unique to wool fiber.



Rarely found in fine wools, the medulla comprises a series of cells (similar to honeycombs) that provide air spaces, giving wool its thermal insulation value. Wool, like residential insulation, is effective in reducing heat transfer.

The Manufacturing Process

The major steps necessary to process wool from the sheep to the fabric are: shearing, cleaning and scouring, grading and sorting, carding, spinning, weaving, and finishing.

1. Shearing

Sheep are sheared once a year usually in the springtime. A veteran shearer can shear up to two hundred sheep per day. The fleece recovered from a sheep can weigh between 6 and 18 pounds (2.7 and 8.1 kilograms); as much as possible, the fleece is kept in one piece.

While most sheep are still sheared by hand, new technologies have been developed that use computers and sensitive, robotcontrolled arms to do the clipping.

2. Grading and sorting

Grading is the breaking up of the fleece based on overall quality. In sorting, the wool is broken up into sections of different quality fibers, from different parts of the body. The best quality of wool comes from the shoulders and sides of the sheep and is used for clothing; the lesser quality comes from the lower legs and is used to make rugs. In wool grading, high quality does not always mean high durability.

Wool is also separated into grades based on the measurement of the wool's diameter in microns. These grades may vary depending on the breed or purpose of the wool. For example:

• < 17.5 - Ultra fine merino

• 17.6-18.5 - Superfine merino

• < 19.5 - Fine merino

• 19.6-20.5 - Fine medium merino

• 20.6-22.5 - Medium merino

• 22.6 < - Strong merino

Or

• < 24.5 - Fine

• 24.5-31.4 - Medium

• 31.5-35.4 - Fine crossbred

• 35.5 < - coarse crossbred

2.

Cleaning and scouring

Wool taken directly from the sheep is called "raw" or "grease wool." It contains sand, dirt, grease, and dried sweat (called suint); the weight of contaminants accounts for about 30 to 70 percent of the fleece's total weight. To remove these contaminants, the wool is scoured


NEHRU ARTS AND SCIENCE COLLEGE in a series of alkaline baths containing water, soap, and soda ash or a similar alkali. The byproducts from this process (such as lanolin) are saved and used in a variety of household products. Rollers in the scouring machines squeeze excess water from the fleece, but the fleece is not allowed to dry completely. Following this process, the wool is often treated with oil to give it increased manageability.

Differences between woolen and worsted

In the spinning operation, the wool roving is drawn out anti twisted into yarn. Woolen

V is chiefly spun on the mule spinning machine. Worsted yarns are spun on any kind of spinning machine mule, ring cap or flyer. The differences between woolen and worsted yarns are as follows:

Woolen yarn

Short staple

Carded only

Slack twisted

Weaker

Bulkier

Softer

Worsted yarn

Lang staple

Carded and combed

Tightly twisted

Stronger

Finer, smoother, even fibres

Harder

Physical and Chemical Properties of Wool

1.

Strength

Wool fibres are weak but wool fabrics are very durable. The durability of wool is the result of the excellent elongation and elastic recovery of the fibres. Fibre strength is not always an indication of durability since flexibility of the fibre and its resistance to abrasion is also important. The tear strength of wool is poor. Wool is fair abrasion resistance. Flexibility of wool is excellent. They can be bent back on themselves 20,000 times without breaking.

2. Resilience

Wool is a very resilient fibre. Its resiliency is greatest when it is dry and lowest when it is wet. It a wool fabric is crushed in the hand, it tends to spring back to its original position when the hand is opened. Because wool fibre has a high degree of resilience, wool fabric wrinkles less than some others; wrinkles disappear when the garment or fabric is steamed.



Good wool is very soft and resilient, poor wool is harsh. When buying a wool fabric, grasp a handful to determine its quality.

3. Heat Conductivity

As wool fibres are poor conductor of heat, they permit the body to retain its normal temperature. Wool garments are excellent for winter clothing and are protective on damp days throughout the year. The scales on the surface of a fibre and the crimp in the fibre create little pockets or air that serve as insulative barriers and give the garment greater warmth.

4. Absorbency

Initially, wool tends to be water-repellent. One can observe that droplets of water on the surface of wool fabrics are readily brushed off. Wool can absorb about 20% of its weight in water without feeling damp; consequently, wool fabrics tend to feel comfortable rather than clammy or chilly. Wool also dries slowly.

5. Cleanliness and Wash ability

Dirt tends to adhere to wool fabric. Consequently, wool requires frequent dry cleaning or laundering if the fabric is washable. Extreme care is required in laundering. Wool is softened by moisture and heat, and shrinking and felting occur when the fabric is washed.

Since wool temporarily loses about 25% of its strength when wet wool fabrics should never be pulled while wet. To control the possibility of shrinking or stretching when laundering a wool sweater or a similar garment, wash it in cold water with an appropriate detergent. To dry the garment, roll it in a towel, squeeze gently to remove as much moisture as possible then spread it out to its original shape on a towel or heavy cardboard.

6. Effect of Heat

Wool becomes harsh at 212°F (100°C) and begins to decompose at slightly higher temperatures. Wool has a plastic quality in that it can be expressed and shaped at steam temperature, whether in fabric as for slacks and jackets, or in felt, as for hats.

7. Effect of Light

Wool is weakened by prolonged exposure to sunlight.

8.

Resistance to Mildew

Wool is not ordinarily susceptible to mildew, but if left in a damp condition, mildew develops.

9. Reaction to Alkalies



Wool is quickly damaged by strong alkalies. The alkali test can be used to identify wool and wool blends. The wool reacts to the alkali by turning yellow, then becoming stick and jellylike, and finally going into solution. If the fabric is a blend, the wool in the blend will disintegrate, leaving only the other fibres. Mild alkali-in warm or cool water-can is used in scouring the raw wool fibres to remove grease.

10. Reaction to Acids

Although wool is damaged by hot sulphuric acid, it is not affected by other acids, even when heated. Acids are used in the manufacture of wool fabrics to remove cellulose impurities, such as leaves or burrs, that may still be in the fabric after weaving. This treatment is called carbonizing.

11. Affinity for Dyes

Because of their high affinity for dyes, wool fabrics dye well and evenly. The use of chrome dyes assures fastness of colour. A variety of other dyes may be effectively used.

12. Resistance to Perspiration

Wool is weakened by alkali perspiration. Garments should be dry cleaned or washed with care to avoid deterioration and odor. Perspiration, generally, will cause discolouration.

13. Flammability

Wools burns very slowly and it self-extinguishing. It is normally regarded as flameresistant. For curtains, carpets and upholstery to be used in trains, planes, ships, hotels and other public buildings, wool is often given a flameretardant finish.

14. Press Retention

Wool also has good press retention. It takes and holds creases well. Creases are set by use of pressure, heat and moisture. During pressing the fibre molecules adjust themselves to the new position by forming new cross-linkages. Creases in wool are not permanent, however, since they can be removed by moisture.

End Uses

Overcoats, suits, dresses and underwear are commonly made from wool. In addition to clothing, wool has been used for carpeting, felt, wool insulation and upholstery. Wool felt covers piano hammers and it is used to absorb odors and noise in heavy machinery and stereo speakers.

HAIR FIBRES



The hair of certain species of other mammals such as goats, alpacas, and rabbits may also be called wool.Hair fibres that have qualities of wool are obtained from certain kinds of throughout the world. The hair of these animals has been so adapted by nature for the climate in which they live that the cloth produced from the fibre gives warmth with Lightweight.

Most specialty wools are obtained from the goat, camel and rabbit families.

Good family Camel family Others

Angora goat - mohair Camel's hair

Angora rabbit - angora

Cashmere goat - cashmere Llama Fur fibres

Alpaca Musk ox-giviut

Vicuina

Guanaco

Mohair

Mohair, the fibre of the Angora goat, is produced in Turkey, South Africa and the

United States. Texas is the largest producer of mohair. The goats are sheared twice a year, in the early fall and early spring.

The raw fleece from the Angora goat is quite long and is of a slightly yellowish or grayish tint, however, when the fleece is washed it comes out a lustrous white. The fibre length is 4 to 6 inches for half a year or 8 to 12 inches for a full year.

Mohair fibres have a circular cross section. It is more uniform in diameter than wool fibre. Mohair shows almost no scales. Mohair is the most resilient natural fibre. It has none of the crimp found in sheep's wool, giving it a smoother surface which is more resistant to dust and more lustrous than wool. Mohair is very strong and has good amity for dyes. It does not attract or hold dirt particles.

The coarse hairs are used for interlinings for ties, suits and coats; the fine hairs are used in woolens and worsted for clothing; the medium quality fibres are used in upholstery and rugs. Mohair is blended with wool, silk; cotton and rayon are also used in combination with these fibres.

Cashmere

The Cashmere goat is native to the Himalaya Mountain region of Kashmir in India,

Mongolia and China. The Cashmere goat is smaller than the Angora goat.

The fleece of this goat has long, straight, coarse outer hair of little value, is made into luxuriously soft wool like yarns. The fibres rang in colour from white to gray to brownish gray. The hair is combed by hand from the animal during the molting season, and care is taken to separate the coarser hair from the fine fibres. Only a small part of the fleece is the


NEHRU ARTS AND SCIENCE COLLEGE very fine fibre, probably not more than 4 oz. per goat. Because supply of the fibre is limited and demand for it is high, cashmere fibre is quite expensive.

Cashmere is more sensitive to the action of alkali than wool. Cashmere is used in high-quality apparel. Fabrics are warm, buttery in hand, and have beautiful draping characteristics. It is used for such garments as sweaters, sports jackets, suits and over coats when a luxurious, soft fabric is desired. It is often blended with wool to reduce the cost of the product.

Camel Hair

This textile fibre is obtained from the two-humped Bactrian camel, which is native to all parts of Asia (Mongolia and Tibet). Each animal sheds about 2.7 kg. (5 lbs.) of fibre per year. Camel hair fabrics are ideal for comfort particularly when used for overcoating, as they are especially warm but lightweight. The best quality is expensive when used alone. It is often minted with wool, thus raising the quality of the wool fabric by adding the fine qualities of camel hair. The price of a mixed cloth is naturally much less than that of a fabric that is 1camel hair.

In the textile industry, camel hair is divided into three grades. Grade 1 is the soft and silky light tan under hair found close to the skin of the camel. This is short staple or roil, of from 1'/." to 3%" (30-90 mm.). Formerly, it was the only true camel hair used in the manufacture of apparel. In wood roils represents the less valuable short-staple; in the hair fibres, the short fibres are the prized product and are only used in high-grade apparel fabrics.

Grade 2 is the intermediate growth, consisting of short hairs and partly of coarse outer hairs, ranging from 1%" to 5" (40-125 mm.) in length.

Grade 3 consists entirely of coarse outer hairs measuring up to 15" (380 mm) in length and in colour from brownish black to reddish brown. It is coarse, tough, stiff and wiry.

It is used in artists' brushes industrial fabric, blankets, press cloths, ropes, cordage and some lower grade apparel fabrics

.

Alpaca

The alpaca is a domesticated animal of the South American branch of the camel family. The alpaca is a small animal about three and one-half feet high and looks like an overt own poodle. The fleece is quite long, reaching almost to the ground. The animals are clipped every second year and yield four to eight pounds of fibres per animal.

The fibre is valued for its silky beauty as well as for its strength. The hair of the alpaca is stronger than ordinary sheep's wool, is water-repellent, and how a high insulative geniality. The staple is 6 to 11"(150-250 mm.) in length and is noted for its softness, fineness and luster. The natural colours of alpaca are white, light fawn, light brown, dark brown, gray, black and piebald.



Lima

The llama is a domesticated animal native to the same geographic area as the alpaca.

Fibres are shorn from the animal once a year, and they are similar in length and diameter to alpaca fibres. The fibres are both coarse and fine and are difficult to separate. Most fabrics produced from llama fibres are made by South America Indians, although some fibre is sold abroad for blending with sheep's wool

Vicuna

The vicuna is the wild animal of the South American branch of the camel family. The vicuna is a small about three feet high (90 cm.) and weight 75 to 100 Ibs. (35 - 45 kg,). A single animal yields only ' lb. (IM gm.) of hair, thus forty animal are required to provide enough hairy for the average coat. To species the vicuna is now under the protection of the

Peruvian and Bolivian governments. Vicuna is the softest, finest, rarest and most expensive of all textile fibres. The fibre is short, very lustrous and a light cinnamon colour.

Guanaco

The guanaco, native to southern Argentina where it is both wild and domesticated, is related to the llamand alpaca. The fibre is extremely soft and silky. It is so light, resilient, and warm and the colour is honey beige. Because of these characteristics and its limited availability, it is expensive. It generally is blended with wool, frequently lamb's wool, so not mask the fibre's soft

Angora

Angara is the hair rabbit, which was raised originally in North Africa and France,

United States, Italy and Japan. Each rabbit produces only a few ounces of hair, and since the rabbits are difficult to raise and produce a small yield the total quantity of Angora is very limited and very expensive. Angora is fairly long, fine, fluffy, soft, smooth, lustrous, slippery and resilient. It requires special processing to spin it properly. It is pure white in colour. It is used primarily far items such sweaters, mittens, baby cloths, millinery and yarns for knitting or knitted fabrics.

Explain about man made fiber?

MAN MADE FIBRES

Synthetic fibers are the result of extensive research by scientists to improve upon naturally occurring animal and In general, synthetic (manmade) fibers are created by forcing, usually through extrusion, fiber forming materials through holes (called spinnerets) into the air, forming a thread. Before synthetic fibrers were developed, artificial (manufactured) fibers were made from cellulose, which comes from plants.



The manufacturing process of regenerated fibres consists of bringing a natural high polymer substance into solution in a suitable way and extruding this solution through a nozzle (orifice), regenerating the same high polymer in the form of a solid filament. A regenerated fibre is one which has a different physical structure than the substance from which it is made, but is essentially the same chemically. Rayon is Regenerated Cellulose, i.e., cellulose that has gone through the manufacturing process, from solid to liquid to solid, without chemical change.

The first artificial fiber, known as artificial silk from 1855 onwards, became known as viscose around 1894, and finally rayon in 1924. A similar product known as cellulose acetate was discovered in 1865. Rayon and acetate are both artificial fibers, but not truly synthetic, being made from wood. Although these artificial fibers were discovered in the mid-nineteenth century, successful modern manufacture began much later

Nylon, the first synthetic fiber, made its debut in the United States as a replacement for silk, just in time for World War II rationing. Its novel use as a material for women's stockings overshadowed more practical uses, such as a replacement for the silk in parachutes and other military uses.

Common synthetic fibers

•

Polyester fiber is used in all types of clothing, either alone or blended with fibres such as cotton.

•

Aramid fiber (e.g. Twaron) is used for flame-retardant clothing, cutprotection, and armor.

• Acrylic is a fibre used to imitate wools, including cashmere, and is often used in replacement of them.

• Nylon is a fibre used to imitate silk; it is used in the production of pantyhose. Thicker nylon fibers are used in rope and outdoor clothing.

•

Spandex (trade name Lycra) is a polyurethane fibre that stretches easily and can be made tight-fitting without impeding movement. It is used to make active wear, bras, and swimsuits.

•

Olefin fiber is a fiber used in active wear, linings, and warm clothing. Olefins are hydrophobic, allowing them to dry quickly. A sintered felt of olefin fibers is sold under the trade name Tyvek.

• Ingeo is a polylactide fiber blended with other fibres such as cotton and used in clothing. It is more hydrophilic than most other synthetics, allowing it to wick away perspiration.

•

Lurex is a metallic fiber used in clothing embellishment.

TWO TYPES OF MAN MADE FIBRES



There are two main categories of man-made fibers: those that are made from natural products (cellulosic fibers) and those that are synthesized solely from chemical compounds

(noncellulosic polymer fibers).

INTRODUCTION OF RAYON FIBRES

Rayon is a natural-based material that is made from the cellulose of wood pulp or cotton.

This natural base gives it many of the characteristics low cost, diversity, and comfort that have led to its popularity and success. Today, rayon is considered to be one of the most versatile and economical man-made fibers available.

The process of manufacturing viscose rayon consists of the following steps mentioned, in the order that they are carried out

1. Cellulose,

2. Steeping,

3. Pressing,

4. Shredding,

5. Aging,

6. Xanthation,

7. Dissolving,

8. Ripening

9. Filtering

10. Degassing,

11. Spinning,

12. Drawing,

13. Washing,

14. Cutting.

The various steps involved in the process of manufacturing viscose are shown in

.



Process of manufacture of viscose rayon fiber.

1.

Cellulose

Purified cellulose for rayon production usually comes from specially processed wood pulp. It is sometimes referred to as dissolving cellulose or dissolving pulp to distinguish it from lower grade pulps used for papermaking and other purposes. Dissolving cellulose is characterized by a high a -cellulose content, i.e., it is composed of long-chain molecules, relatively free from lignin and hemicelluloses, or other short-chain carbohydrates.

2. Steeping

The cellulose sheets are saturated with a solution of caustic soda (or sodium hydroxide) and allowed to steep for enough time for the caustic solution to penetrate the cellulose and convert some of it into soda cellulose, the sodium salt of cellulose. This is necessary to facilitate controlled oxidation of the cellulose chains and the ensuing reaction to form cellulose xanthate.



3. Pressing

The soda cellulose is squeezed mechanically to remove excess caustic soda solution.

4. Shredding

The soda cellulose is mechanically shredded to increase surface area and make the cellulose easier to process. This shredded cellulose is often referred to as white crumb

5. Aging

The white crumb is allowed to stand in contact with the oxygen of the ambient air.

Because of the high alkalinity of white crumb, the cellulose is partially oxidized and degraded to lower molecular weights. This degradation must be carefully controlled to produce chain lengths short enough to give manageable viscosities in the spinning solution, but still long enough to impart good physical properties to the fiber product.

6. Xanthation

The properly aged white crumb is placed into a churn, or other mixing vessel, and treated with gaseous carbon disulfide. The soda cellulose reacts with the CS2 to form xanthate ester groups. The carbon disulfide also reacts with the alkaline medium to form inorganic impurities which give the cellulose mixture a characteristic yellow color and this material is referred to as yellow crumb. Because accessibility to the CS2 is greatly restricted in the crystalline regions of the soda cellulose, the yellow crumb is essentially a block copolymer of cellulose and cellulose xanthate.

7. Dissolving

The yellow crumb is dissolved in aqueous caustic solution. The large xanthate substituents on the cellulose force the chains apart, reducing the interchain hydrogen bonds and allowing water molecules to solvate and separate the chains, leading to solution of the otherwise insoluble cellulose. Because of theblocks of un-xanthated cellulose in the crystalline regions, the yellow crumb is not completely soluble at this stage. Because the cellulose xanthate solution (or more accurately, suspension) has a very high viscosity, it has been termed viscose.



8. Ripening

The viscose is allowed to stand for a period of time to ripen. Two important processes occur during ripening: Redistribution and loss of xanthate groups. The reversible xanthation reaction allows some of the xanthate groups to revert to cellulosic hydroxyls and free CS2.

This free CS2 can then escape or react with other hydroxyl on other portions of the cellulose chain. In this way, the ordered, or crystalline, regions are gradually broken down and more complete solution is achieved. The CS2 that is lost reduces the solubility of the cellulose and facilitates regeneration of the cellulose after it is formed into a filament.

9. Filtering

The viscose is filtered to remove undissolved materials that might disrupt the spinning process or cause defects in the rayon filament

10. Degassing

Bubbles of air entrapped in the viscose must be removed prior to extrusion or they would cause voids, or weak spots, in the fine rayon filaments.

11. Spinning - (Wet Spinning)

The viscose is forced through a spinneret, a device resembling a shower head with many small holes. Each hole produces a fine filament of viscose. As the viscose exits the spinneret, it comes in contact with a solution of sulfuric acid, sodium sulfate and, usually,

Zn++ ions. Several processes occur at this point which cause the cellulose to be regenerated and precipitate from solution. Water diffuses out from the extruded viscose to increase the concentration in the filament beyond the limit of solubility. The xanthate groups form complexes with the Zn++ which draw the cellulose chains together. The acidic spin bath converts the xanthate functions into unstable xantheic acid groups, which spontaneously lose

CS2 and regenerate the free hydroxyls of cellulose. (This is similar to the well-known reaction of carbonate salts with acid to form unstable carbonic acid, which loses CO2). The result is the formation of fine filaments of cellulose, or rayon.

12. Drawing

The rayon filaments are stretched while the cellulose chains are still relatively mobile.

This causes the chains to stretch out and orient along the fiber axis. As the chains become more parallel, interchain hydrogen bonds form, giving the filaments the properties necessary for use as textile fibers.

13. Washing

The freshly regenerated rayon contains many salts and other water soluble impurities which need to be removed. Several different washing techniques may be used.



14. Cutting

If the rayon is to be used as staple (i.e., discreet lengths of fiber), the group of filaments (termed tow) is passed through a rotary cutter to provide a fiber which can be processed in much the same way as cotton.

6.2.1 Physical and Chemical Properties of Rayon

1. Strength

The tensile strength of viscose rayon is greater than that of wool, but is only about half as great as that of silk. Viscose rayon is also weaker than cotton and linen and its strength is reduced 40 to 70% when wet. The strength is controlled by stretching, which causes a greater orientation of the molecules. Viscose is easily stretched when wet and swollen. If dried in a stretched condition, it will relax and shrink upon again becoming wet.

2. Elasticity

Viscose rayon has greater elasticity than cotton or linen but less than wool or silk.

3. Drapability

Viscose rayon possesses a marked quality of drapability because it is a relatively heavyweight fabric. The filament can be made as coarse as desired depending on the holes in the spinneret.

4. Resilience

Viscose rayon lacks the resilience natural to wool and silk and creases readily; but it should be remembered that the resistance of a fabric to creasing depends on the kind of yarn, weave, and finishing process.


Viscose rayon is a good conductor of heat and is therefore appropriate for summer clothing. Spun rayon fabrics, however, are adaptable to winter apparel because they can be napped.

6. Absorbency

Viscose rayon is a one of the most absorbent of all textiles. It is more absorbent than cotton or linen. The combination of high heat conductivity and high absorbency of rayon makes it very suitable for summer wear.



7. Cleaning and Washability

Because of its smoothness, viscose, rayon fibre helps to produce hygienic fabric that shed dirt. Some viscose rayon fabrics wash easily, and depending on the finish that may be given to them, they will not become yellow when washed or dry cleaned. Regular rayon fabrics have limited washability because of the low strength of the fibre when wet. When laundered, a mild soap or detergent and warm water should be used.

8. Shrinkage

Viscose rayon fabrics tend to shrink more than cotton fabrics of similar construction. Knitted fabric always shrinks more than flat woven fabrics because of the nature of the construction. When spun viscose rayon is blended with wool, the great amount of shrinkage characteristic of the wool is reduced.

9. Affect of Heat

Since viscose rayon is a pure cellulose fibre, it will burn in much the same manner as cotton. Application of heat at 300°F (150°C) causes viscose rayon to lose strength; above 350°F (177°C), it begins to decompose.


Viscose rayon has generally good resistance to sunlight, though prolonged exposure of intermediate tenacity rayon results in faster deterioration and yellowing.

11. Resistance to Mildew

Like cotton, viscose rayon has a tendency to mildew. Moths are not attracted to cellulose. Consequently, moth-proffering treatments are not necessary for viscose rayon.

Resistance to other insects is also similar to that of cotton.


Viscose rayon is fairly resistant to alkalies and oxidizing agents but tends to be harmed to a greater extent by alkalies than are cotton or linen. A mild soap and warm water is recommended when laundering such garments.


Viscose rayon reacts to acids in a manner similar to cotton. It is harmed by acids.Being pure cellulose, the fabric is disintegrated by hot dilute and cold concentrated acids.Viscose rayon has good affinity for most cotton dyes. Viscose rayon fabrics absorb dyes evenly and can be dyed with a variety of dyes, such as direct, acid, chrome and disperse.

Coloured viscose rayons have a high resistance to sunlight. This property makes them suitable for window curtains.




Viscose rayon is fairly resistant to deterioration from perspiration. The colour, however, is not usually as resistant as the fabric and will fade if not solution-dyed.

Major Rayon Fiber Uses

•

Apparel: Accessories, blouses, dresses, jackets, lingerie, linings, millinery, slacks, sport shirts, sportswear, suits, ties, work clothes

•

Home Furnishings: Bedspreads, blankets, curtains, draperies, sheets, slipcovers, tablecloths, upholstery

•

Industrial Uses: Industrial products, medical surgical products, nonwoven products, tire cord

•

Other Uses: Feminine hygiene products

ACETATE RAYON

• Cellulose + Glacial Acetic Acid + Acetic Anhydride + Sulphuric acid (Cotton linter, wood pulp)

• Frimary Cellulose Acetate + Water

• (Cellulose tri-acetate)

• Secondary Cellulose Acetate + Acetone

• Acetate Spinning Solution .

• Dry Spinning in Warm Air Acetate Filament

INTRODUCTION OF NON CELLOUSIC FIBRE





Cotton linters or wood chips are converted into sheets of pure cellulose. The cellulose is steeped in glacial acetic acid and aged for a period of time under a controlled temperature.

After aging, it is thoroughly mixed with acetic anhydride.

A small amount of sulphuric acid is then added as a catalyst to facilitate a reaction producing a thick, clear liquid solution of cellulose acetate. After further aging, water is added, and causing the cellulose acetate to precipitate as whiteflasks. The flasks are dried, dissolved in acetone, and filtered several times to remove impurities. The result is clear, white spinning solution of the consistency of syrup.

If delustered yarn is required, titanium dioxide, a delusterant, is added at this stage to produce the desired degree of brightness: bright, semi dull, or dull. Dyestuff may be added to the spinning solution to provide superior colourfastness.

After the delusterant has been added, the spinning solution is forced through a spinneret and into a cabinet of heated air that evaporates the acetone and solidifies the filament. The filaments are then ready for winding on spools, cones, or bobbins ready for shipping to the mills for weaving or knitting. Staple fibres are cut, crimped, lubricated, dried, and baled for shipment.

Physical and Chemical Properties of Acetate

The properties of acetate fabrics will vary to some extent depending on the type of yam used (filament, textured, or spun), on the type of fabric construction, and on the finish.

1. Strength

Acetate is not a strong fibre. It is weaker than any rayon and is, in fact, one of the weakest textile fibres. It loses much of its strength when wet.

2. Elasticity

Acetate is more elastic than any rayon.

3. Resilience

Acetate is more wrinkle resistant than any rayon; consequently, the fabric will tend to return to its original shape much better than will rayon after it is pulled or crumpled. After washing, acetate garments should be carefully hung to permit the yams to relax to their original shape.

4. Durability

Acetate fabrics have good body and flexibility and therefore drape very nicely.




Acetate does not have as high a rate of heat conductivity as rayon and therefore is warmer. Acetate is consequently more useful for linings and warmer clothing, particularly if it is spun acetate.

6. Absorbency

Acetate is not very absorbent. It absorbs only half as much moisture as the rayon’s.

Acetate fabric gets wet mostly on the surface and will not become saturated; therefore; they dry quickly. This makes acetate very suitable for shower curtains, umbrellas, and rain coats.

It is also suited for bathing suits, particularly at the seashore because salt water does not have any deteriorating effect on acetate. On the other hand, acetate is uncomfortable in warm, humid weather because of its low absorbency. Acetate garments, such as blouses and lingerie, worn next to the skin feel clammy and uncomfortable because they do not absorb atmospheric humidity.

7. Cleanliness and Wash ability

Acetate fibre smoothness helps to produce hygienic fabrics that shed dirt and wash easily. They will not become yellow when washed or dry cleaned. Since acetate temporarily loses some strength when wet such fabrics must be handled with care when washed. When laundered, a mild soap or detergent and warm water should be used. The garments should not be rubbed rigorously but should be handled gently and squeezed to remove the water. They will dry readily and should be hung so that the water wilts drip off. Acetate garments dry clean well.

8. Effect of Bleaches

White acetate remains white, and acetate fabrics need not be bleached. If bleaching is desired, it should be done with a very mild solution of hydrogen peroxide or a very dilute solution of sodium hypochlorite.

9. Shrinkage

Acetate fabrics will shrink less than any rayon. Sometimes they are given a shrink resistant finish.

10. Effect of Heat

Acetate fabrics need less ironing than rayon fabrics. A warm iron will easily smooth out an acetate fabric, particularly if the fabric is a little damp. If the from is too hot, it will melt the acetate causing it to stick to the iron and make the fabric stiff.




Acetate is more resistant to the effect of light than cotton or any rayon. Over a period of time, acetate will be weakened from exposure to light.

12. Resistance to Mildew

Acetate is highly resistant to mildew. It is ideal for fabrics exposed to moisture, such as shower curtains.


Strong alkalies should not be used on acetate since they cause a chemical change in the fibre.


Acetate is more resistant to acids than pure cellulose, but it will be decomposed by concentrated solutions of strong acids.


Acetate fabrics are fairly resistant to deterioration by perspiration, but the colour will be affected if it has not been solution-dyed.

Production method

Regular rayon (or viscose) is the most widely produced form of rayon. This method of rayon production has been utilized since the early 1900s and it has the ability to produce either filament or staple fibers. The process is as follows:

• Cellulose

: Production begins with processed cellulose

•

Immersion:

The cellulose is dissolved in caustic soda

• Pressing

: The solution is then pressed between rollers to remove excess liquid

•

White Crumb

: The pressed sheets are crumbled or shredded to produce what is known as

"white crumb"

•

Aging:

The "white crumb" aged through exposure to oxygen

•

Xanthation:

The aged "white crumb" is mixed with carbon disulfide in a process known as Xanthation

•

Yellow Crumb:

Xanthation changes the chemical makeup of the cellulose mixture and the resulting product is now called "yellow crumb"



• Viscose

: The "yellow crumb" is dissolved in a caustic solution to form viscose

• Ripening:

The viscose is set to stand for a period of time, allowing it to ripen

•

Filtering:

After ripening, the viscose is filtered to remove any undissolved particles

• Degassing: Any bubbles of air are pressed from the viscose in a degassing process

•

Extruding:

The viscose solution is extruded through a spinneret, which resembles a shower head with many small holes

•

Acid Bath:

As the viscose exits the spinneret, it lands in a bath of sulfuric acid resulting in the formation of rayon filaments

•

Drawing:

The rayon filaments are stretched, known as drawing, to straighten out the fibers

• Washing:

The fibers are then washed to remove any residual chemicals

• Cutting:

If filament fibers are desired the process ends here. The filaments are cut down when producing staple fibers.

NYLON

Any synthetic plastic material composed of polyamides of high molecular weight and usually, but not always, manufactured as a fibre. Nylons were developed by Du Pont in the

1930s. The successful production of a useful fibre by chemical synthesis from compounds readily available from air, water, and coal or petroleum stimulated expansion of research on polymers, leading to a rapidly growing family of synthetics.

Basic Concepts of Nylon Production

• The first approach: combining molecules with an acid (COOH) group on each end are reacted with two chemicals that contain amine (NH2) groups on each end.

This process creates nylon 6, 6, made of hexamethylene diamine with six carbon atoms and acidipic acid, as well as six carbon atoms.

• The second approach: a compound has an acid at one end and an amine at the other and is polymerized to for a chain with repeating units of (-NH- [CH2]n-CO-)x. o In other words, nylon 6 is made from a single six-carbon substance called caprolactam. O In this equation, if n=5, then nylon 6 is the assigned name. (May also be referred to as polymer)

Manufacturing of Nylon



• Carbon + Nitrogen + Hydrogen + Oxygen (coal) (air) (water) (air)

+

• Adipic Acid and Hexamethylene Diamine

• Amide (Nylon Salt)

• Heated in Vaccum (Loss of Water)

• Nylon Super Polymer

�

Heated

• Nylon Spinning Solution (Polyamide)

�

Dry Spinning (Cool Air)

�

Drawing and Stretching

• Nylon Filament

Flow Diagram for a Process Used to Manufacture Nylon

Nylon is actually a group of related chemical compounds. It is composed of hydrogen, nitrogen, oxygen and carbon in controlled proportions and structural arrangement.

Variations can result in types of nylon plastics, such as combs, brushes, and gears.

By a series of chemical steps beginning with such raw materials as coal, petroleum, or such cereal byproducts as oat hulls or corncobs, two chemicals called hexamethylene diamine and adipic acid are made. These are combined to form nylon salt. Then, since the nylon salt is to be shipped to the spinning mill, it is dissolved in water for easily handling. At the spinning mill, it is heated in large evaporators until a concentrated solution is obtained.

The concentrated nylon salt solution is then transferred to an autoclave, which is like a h e pressure cooker. The heat combines the molecules of the two chemicals into giant chainlike ones, called linear super polymers. The linear super polymer is then allowed to flow out of a


NEHRU ARTS AND SCIENCE COLLEGE slot in the autoclave onto a slowly revolving casting wheel. As the ribbons of molten nylon resin are deposited on the wheel, they are sprayed with cold water, which hardens them to milky white opaque ribbons. The ribbons are removed from the casting wheel to a chipper, which transforms them into flakes.

Nylon flakes are blended and poured into the hopper of the spinning machine to insure uniformity in the final nylon yarn. Through a value in the bottom of the hopper, the nylon flakes fall onto a hot grid, which melt, them? The molten nylon is pumped through a send filter to the spinneret. The spinneret has one or more holes, depending on the purpose for which the yarn is to be made. As the filaments come out of the spinneret and hit the air, they solidify. This filament can be changed, however, by stretching or cold drawing, the filaments from two to seven times their original length. The amount of stretching is dependent on the diameter, elasticity, and strength desired. As the filaments are stretched, they become more and more transparent. The polyamide molecules straighten out, become parallelized, and are brought very close together. Up to a point, the nylon becomes stronger, more elastic, more flexible and more pliable.

Physical and Chemical Properties of Nylon

1.

Strength

Nylon is produced in both regular and high tenacity strengths. Although one of the lightest textile fibre, it is also one of the strongest. The strength of nylon will not deteriorate with age.

2. Elasticity

Nylon is one of the most elastic fibre that exists today, though it does not have the exceptional elastic quality of spandex fibre. After being stretched, nylon has a strong natural tendency to return to its original shape, and has its own limit to elasticity. If stretched too much, it will not completely recover its shape. Spun nylon is not as elastic as filament nylon.

3. Resilience

Nylon has excellent resilience. Nylon fabrics retain their smooth appearance, and wrinkles from the usual daily activities fall out readily.

4. Shrinkage

Nylon has good dimensional stability and retains its shape after being wet.

5. Drapability

Fabrics at nylon yarn have excellent draping qualities. Lightweight sheers may have a flowing quality, medium-weight dress fabrics can drape very nicely, and heavier weight jacquards also drape well.



6. Heat Conductivity

Nylon fabrics may or may not conduct heat well. The warmth or coolness of a nylon garment depends on the weave of the fabric and on the type of yarn used. The smoothness, roundness, and fineness of nylon filaments permit the manufacture of very smooth, very fine yarns, which can be packed very closely when weaving the fabric. If nylon fabric is woven compactly, it will not be porous. The tight construction will not permit air to circulate through the fabric, and the heat and moisture of the body will not readily pass through it but will built up between the fabric and the body: so, the wearer will feel very warm

.

7. Absorbency

Nylon does not absorb much moisture. Fabrics made of nylon filament yarns will not readily wet through the material-most of the water remains on the surface and runs off the smooth fabric, which therefore dries quickly. Such fabrics are useful for rain coats and shower curtains. Spun nylon fabrics, however, will not dry quickly. Nylon's low absorbency has a disadvantage in that the fabric feels clammy and uncomfortable in warm, humid weather.

8. Cleanliness and Washability

Because of nylon's smooth surface, dirt and stains often come clean merely using a damp cloth. To wash nylon garments by hand or washing machine, use lukewarm water at

100°F (38°C) and a detergent or soap with a water softener.

Nylon filament fabrics dry very quickly. They need little or no ironing because the garments are usually heat set to retain their shape, pleats or creases. Spun nylon has a tendency to pill or form balls, on the surface of the fabric. To minimize thus, such fabrics should not be rubbed. They should be washed gently, preferably by hand. Brushing with a soft brush will reduce the pilling.

9. Effect of Heat

Like acetate, nylon will melt if the iron is too hot, therefore, the iron should be set at the proper heat level. It does not burn readily but melts to form glossy beads formation.

10. Effect of Light



Bright nylon is more resistant to the effects of sunlight than most other fibres. Dull nylon will deteriorate a little more quickly than bright nylon; however, even dull nylon has good resistance to light.

11. Resistance to Mildew and Insects

Mildew has absolutely no effect on nylon. Mildew may form on nylon, but it will not weaken the fabric. Moths and other insets will not attack nylon because it has no attraction for them.

12. Reaction to Alkalies

Nylon is substantially inert to alkalies. No reaction with soap, alkalis and alcohols.

1

3. Reaction to Acids

Nylon is decomposed by cold concentrated solutions of such mineral acids as hydrochloric, sulphuric and nitric acids. A boiling dilute 5% solution of hydrochloric will destroy nylon

Major End Uses

• Apparel - swimwear, active wear, intimate apparel, foundation garments, hosiery, blouses, dresses, sportswear, pants, jackets, skirts, raincoats, ski and snow apparel, windbreakers, children’s wear.

• Home Fashions - carpets, rugs, curtains, upholstery, draperies, bedspreads

• Other - Luggage, back packets, life vests, umbrellas, sleeping bags, tents.

POLYSTER

Polyester is a synthetic fiber derived from coal, air, water, and petroleum.

Developed in a 20th-century laboratory, polyester fibers are formed from a chemical reaction between an acid and alcohol. In this reaction, two or more molecules combine to make a large molecule whose structure repeats throughout its length. Polyester fibers can form very long molecules that are very stable and strong.

Manufacturing of Polyester

• Terephthalic Acid + Ethylene Glycol o Polymerization

• Polyester + Highly Heated



• Polyester Spinning Solution o Melt or Dry Spinning (Cool Air)

• Filament o Drawing and Stretching

• Polyester Filament

Flow Diagram Polyester Process

1.

Polymerization

• To form polyester, dimethyl terephthalate is first reacted with ethylene glycol in the presence of a catalyst at a temperature of 302-410Â°F (150- 210Â°C).



• The resulting chemical, a monomer (single, non-repeating molecule) alcohol, is combined with terephthalic acid and raised to a temperature of 472Â°F (280Â°C). Newly-formed polyester, which is clear and molten, is extruded through a slot to form long ribbons.

2.

Drying

• After the polyester emerges from polymerization, the long molten ribbons are allowed to cool until they become brittle. The material is cut into tiny chips and completely dried to prevent irregularities in consistency.

3.

Melt spinning

• Polymer chips are melted at 500-518Â°F (260-270Â°C) to form a syrup-like solution. The solution is put in a metal container called a spinneret and forced through its tiny holes, which are usually round, but may be pentagonal or any other shape to produce special fibers. The number of holes in the spinneret determines the size of the yarn, as the emerging fibers are brought together to form a single strand.

• At the spinning stage, other chemicals may be added to the solution to make the resulting material flame retardant, antistatic, or easier to dye.

4.

Drawing the fiber

• When polyester emerges from the spinneret, it is soft and easily elongated up to five times its original length. The stretching forces the random polyester molecules to align in a parallel formation. This increases the strength, tenacity, and resilience of the fiber. This time, when the filaments dry, the fibers become solid and strong instead of brittle.

• Drawn fibers may vary greatly in diameter and length, depending on the characteristics desired of the finished material. Also, as the fibers are drawn, they may be textured or twisted to create softer or duller fabrics.

5.

Winding

• After the polyester yarn is drawn, it is wound on large bobbins or flatwound packages, ready to be woven into material.

Physical and Chemical Properties of Polyester

1.

Strength

Polyester fibres may be characterized as relatively strong fibres. Fabrics of regular tenacity polyester filament yarns are very strong and durable. The high tenacity polyester filament yarns are very strong and durable. The high tenacity polyester filament yarns used for tires and industrial purposes are extremely strong; some types are the strongest of all textiles


NEHRU ARTS AND SCIENCE COLLEGE except glass, aramid etc. The staple fibres also vary in strength depending on the type of fibre.

2.

Elasticity

Polyester fibres do not have a high degree of elasticity. In general, polyester fibre is having a high degree of stretch resistance. Thus property makes polyester suited for knitted garments; sagging and stretching that would ordinarily occur are reduced. Fabrics of polyester fibre have good dimensional stability.

3.

Resilience

Polyester fibre has a high degree of resilience. Not only does a polyester fabric resist wrinkling when dry, it also resists wrinkling when wet. And heat set polyester fibre is suitably resilient for .use in carpets.

4.

Drapability

Fabrics of polyester filament yarn have satisfactory draping qualities. Staple polyester can produce spun yarn that is more flexible and softer, thereby imparting the draping quality.

Drapability of fabrics of blended polyester staple will depend upon the type and proportion of blend in the yam as well as the fabric construction.

5.

Heat Conductivity

Fabrics of polyester fibre are better conductors of heat. The basic polyester filament fibre is round. This results in a smoother yarn woven into fabrics with fewer air spaces and less insulation. Polyester staple fibre is crimped and this does provide greater insulation in the yarns and fabrics

.

6.

Absorbency

Polyester is one of the least absorbent fibres. This low absorbency has two important advantages. Polyester fabrics will dry very rapidly since almost all the moisture will lie on the surface rather than penetrate the yarns. Fabrics of polyester fibre are therefore well suited for water-repellent purposes, such as rainwear. Furthermore, this low absorbency means that polyester fabrics will not stain easily. Many substances lie on the surface and can be wiped or washed off easily.

7.

Cleanliness and Washability

Since polyester fibres are smooth and have a very low absorbency, many stains lie on the surface and can easily be washed by hand or machine. Strong soaps are not needed. When ironing polyester fabrics, it is best to use low to medium heat.



8.

Effect of Bleaches

Polyester fabrics maybe safety bleached because polyester had good resistance to deterioration by household bleaches. If the polyester has an optical brightener, no bleaching is necessary.

9.

Shrinkage

Polyester fabrics shrink as much as 20% during wet-finishing operations. Finished polyester woven and knitted fabric will not shrink. They have excellent dimensional stability.

10.

Effect of Heat

Depending upon the type, pohester will get sticky at 440 to 468°F (227-242°C).

Therefore, if ironing is needed, it should be done at lower temperatures. At temperature in the range of 480 to 554°F (249290°C), polyester will melt and flame.

11.

Effect of Light

Polyester has good resistance to sunlight. Fabrics of polyester are therefore well suited for outdoor use. Over a prolonged period of exposure to direct sunlight, however, there will be a gradual deterioration of the polyester fibre. When exposed to sunlight behind glass, polyester shows a considerable increase in resistance to sunlight, it has a marked superiority over most other fibres under these conditions and is very well suited for curtains.

12.

Resistance to Mildew and Insects

Polyester fabrics are absolutely resistant to mildew. They will not be stained or weakened. Mildew should readily wash off the fabrics without any deterioration to it.

13.

Reaction to Alkalies

At room temperature, polyester has good resistance to weak alkalies and fair resistance to strong alkalies. This resistance is reduced with increased temperature. At boiling temperature, it has poor resistance to weak alkalies and dissolves in strong alkalies.

14.

Reaction to Acids

Depending upon the type, polyester has excellent to good resistance to mineral and organic acids. Highly concentrated solution of a mineral acid, such as sulphuric acid, at relatively high temperatures will result in degradation.

15. Affinity for Dyes



Polyester can be dyed with appropriate disperse, azoic, and developed dyes at high temperatures, producing a good range of shades that have good-to-excellent wash fastness and fair-to-good light fastness.

16.

Resistance to Perspiration

Polyester has no significant loss of strength from continued contact with either acid or alkaline perspiration.

Major End Uses

• Apparel - essentially every form of clothing, dresses, blouses, jackets, separates, sportswear, suits, shirts, pants, rainwear, lingerie, childrenswear

• Home Fashions - curtains, draperies, floor coverings, fiber fill, upholstery, bedding

ACRYLIC

Acrylic fibers are synthetic fibers made from a polymer (Polyacrylonitrile) with an average molecular weight of ~100,000. To be called acrylic in the U.S., the polymer must contain at least 85% acrylonitrile monomer. Typical co monomers are vinyl acetate or methyl acrylate.

Manufacturing of Acrylic

The term acrylic comes from the chemical composition of the fibre; the word modacrylic comes from "modified acrylic". Dimethylfromamide or dimethylacetamide is used as a solvent. Some fibres can be spun from acetone.


1. Explain in detail about the Manufacturing process ,properties and uses of natural fibres – cotton ,linen ,Jute , pineapple,hemp ,silk , wool, hair fibers, man-made fibres –

Viscose rayon ,acetate rayon , nylon, polyester,acrylic.

___________________________________________________________________________




STUDY MATERIAL


SEMESTER : II


UNIT : 1II

SYLLABUS

Spinning –Definition, Classification – Chemical and mechanical spinning –blending , opening, cleaning ,doubling ,carding ,combing ,drawing ,roving ,spinning.

Yarn classification – definition, classification – simple and fancy yarns, Sewing threads and it properties.

___________________________________________________________________________

SECTION-A

1.

Spinning is the art of producing continuous, twisted Strands, of a desire size, from fibrous materials.

2.

Blending refers to the bringing together of fibres from different origins

3.

Spinning is also used for the production of monofilaments from synthetic polymers.

4.

Carding processes in yarn manufacture in which the fibres are brushed .

5.

Twisting Process of combining two or more parallel single or ply yams by twisting together to produce a ply-yarn or cord.

Explain about spinning?

INTRODUCTION OF SPINNING

Spinning is an ancient textile art in which plant, animal or synthetic fibers are twisted together to form yarn (or thread, rope, or cable). For thousands of years, fiber was spun by hand using simple tools, the spindle and distaff. Only in the early Medieval era did the spinning wheel increase the output of individual spinners, and mass-production only arose in the 18th century with the beginnings of the Industrial Revolution. Hand-spinning remains a popular handicraft. The fabrication of yarn (thread) from either discontinuous natural fibers or bulk synthetic polymeric material. In a textile context the term spinning is applied to two different processes leading to the yarns used to make threads, cords, ropes, or woven or knitted textile products.

History

The earliest spinning probably involved simply twisting the fibers in the hand.

Later a stick, called a spindle, was used to add the twist and hold the twisted fiber. Usually a whorl or weight stabilizes the spindle. The spindle is spun and twists the fiber until it becomes yarn. The spindle may be suspended or supported. Later the spinning wheel was developed which allowed continuous and faster yarn production. Spinning wheels may be


NEHRU ARTS AND SCIENCE COLLEGE foot, hand or electrically powered. The hand-turned spinning wheel called a charkha was prevalent in India and was used by Gandhi and his followers.

Modern powered spinning, originally done by water or steam power but now done by electricity, is vastly faster than hand-spinning. New techniques including Open End spinning or rotor spinning can produce yarns at rates in excess of 40 meters per second per spinning head.

DEFINITION

Spinning is the art of producing continuous, twisted Strands, of a desire size, from fibrous materials. In a broad sense, the term is used to include all the operations through which cotton fibers are passed until they become yarn. It is customary to speak of a "spinning mill" to distinguish it from a "weaving mill" or a “finishing plant”. In a narrow sense, spinning applies only to that operation which takes roving, further draws and twists it, and produces yarn.

Objects

1.

Mixing

• The term mixing refers to the bringing together of two or more varieties of the same basic fibre

• For example, Egyptian cotton fibre combined with American cotton fibre, so that the final yarn remains 100% cotton

2.

Blending

• Blending refers to the bringing together of fibres from different origins

• For example, wool and silk or cotton and polyester

3.

Cleaning and fibre separation

• All bales of raw fibres contain a variety of impurities that need to be removed

• The first process is to divide and split the bales into smaller and smaller loose bunches, to remove dust, seeds and unwanted debris

• Some fibre types are then washed or scoured

• Others can be combed or carded to further separate and clean the fibres

. Fibre alignment



• This process follows carding and combing

• Several slivers or groups of carded or combed fibres are combined to form a single sliver of straightened fibres

• The process is called drawing

4.

Drafting and twisting

• Drafting is the process of gently drawing out the sliver to reduce it's linear density or thickness

• Exactly how this is done and what machinery is used depends on the required yarn quality and count

• The final process is to insert the required amount of twist into the single yarn

CLASSIFICATION OF SPINNING

Spinning can be classified in two methods based on its yarn production technique.

1. Mechanical Spinning

2. Chemical Spinning

1. Mechanical Spinning Methods

• There are a large number of different spinning methods

• Here we will look at some of the most relevant,ring spun, rotor spun, twistless, wrap spun and core spun yarns

1.

Ring spun yarns

• The most popular method of staple fibre yarn production

• The fibres are twisted around each other to give strength to the yarn

2.

Rotor spun yarns

• Similar to ring spinning

• Generally rotor spun yarns are only made from short staple fibres

• Rotor spinning produces a more regular, smoother yarn than ring spinning

• Rotor spun yarn is weaker than ring spun

3.

Twistless yarns

• Rather than being twisted, the fibres are held together by some form of adhesive

• The glued fibres are often laid over a continuous filament core

4.

Wrap spun yarns



• The yarns are made from staple fibres bound by another yarn

• The binding yarn is usually a continuous man-made filament yarn

• They can be made from either short or long staple fibres

5.

Core spun yarns

• Core spun yarns have a central core wrapped with staple fibres

• They are produced in one operation at the time of spinning

• For example, a cotton outer for handle and comfort, with a filament (often polyester) core for added strength, (lots of sewing threads) or cotton over an electrometric core (shirring elastic)

Chemical spinning

The term spinning is also used for the production of monofilaments from synthetic polymers for example, polyamides or nylons, polyesters, and acrylics or modified natural polymers, such as cellulose-rayon. These semi synthetic and fully synthetic fibres can be produced by the suitable following methods.

1. Dry spinning

2. Wet spinning

3. Melt spinning

MATERIALS USED

Yarn can be made from a wide variety of materials:

• Plant fibers: cotton, flax (to produce linen), bamboo, ramie, hemp, nettle , raffia, yucca, coconut husk, banana trees, and soy

• Animal fibers: wool, goat (angora, or cashmere goat), rabbit (angora), llama, alpaca, dog, cat, camel, yak, qiviut (from Musk Ox), and silk

• Synthetic fibers fibers: nylon, rayon (derived from wood pulp), acetate, polyester, tencel

(derived from wood pulp), and ingeo (derived from corn)

• Mineral fibers: asbestos

COTTON SPINNING SYSTEM



Spinning is process of manufacturing cotton fibre into yarn. This includes the general operations of opening, picking, carding, drawing, roving and ring spinning in the production of the so called "carded yams". For "combed yams", three steps culminating in

`combing' are included after the carding operation.

1.

Ginning

Ginning is the process of separating the lint cotton from the seed.

2. Blending

A Process or processes concerned primarily with the mixing of various lots of fibres to produce a homogeneous mass. Blending is normally carried out to mix fibres, which may or may not be of similar physical or chemical properties, market values, or colours.

Blending is also used to ensure consistency of end product.

2.

Opening

Covers the initial treatments given to raw cotton. the separation and opening up of the cotton to remove compression because of baling and shipping. Heavier impurities are also removed from the stock.

3. Picking

The final operation in the cotton system preparation line, in which the cotton flocks are opened mechanically, cleaned, and formed into a lap of specified mass per unit area, for feeding to a carding machine.

3.

Carding

The processes in yarn manufacture in which the fibres are brushed up, made more or less parallel have considerable portions of foreign matter removed, and are put into a manageable form known as sliver.

4.

Drawing

Operations by which slivers are blended. Doubled or leveled, and by drafting reduced to a sliver or a roving suitable for spinning.

5.

Combing

The straightening and parallelizingof fibres and the removal of short fibres and impurities by using a comb or combs assisted by brushes and rollers.

8. Roving



A loose assemblage of fibres drawn into a single strand, with very' little twist. It is an intermediate state between sliver and yarn

9. Spinning

The final operation in cotton yarn manufacture. It completes the working of the cotton fibres into a commercial, fine, coherent yarn sufficiently twisted so that it is now ready for weaving purposes.

6.

Doubling

The number of laps, slivers, slubbings. or rovings fed simultaneously into a machine for drafting into a single end. Doubling is employed to promote blending and regularity.

7.

Twisting

Process of combining two or more parallel single or ply yams by twisting together to produce a ply-yarn or cord. Ply yarns result from twisted single yarns and cords and cables from twisted ply yarns. Twisting is also employed to obtain greater strength and smoothness, increased uniformity in yam.

Classification of Yarn Forming Operations for Cotton Yarns

Yarn Forming Operations

GINNING AND BALING

Purpose of ginning

Ginning should be considered as the first actual mill processing of cotton, because generally this is the first mechanical process to which raw cotton is subjected, unless


NEHRU ARTS AND SCIENCE COLLEGE the cotton has been harvested by machine. The complete ginning operation consists of any preliminary cleaning and drying of the cotton, separation of the seed from the cotton fibres, often referred to as lint, and pressing and wrapping the cotton into a bale of approximately

500 lb. This latter process is known as baling.

The amount of pre-cleaning or pre-diving which may be necessary depends on the condition of the cotton as it is brought from the fields to the gin. Methods of harvesting usually determine what amount of pre-cleaning will be necessary; cleanly hand-picked cotton requires no pre-cleaning. While roughly handsnapped or mechanically stripped cotton requires a considerable amount of precleaning before reaching the actual operation of separating the seed from the lint.

Gin Types

There are two types of gin in operation today:

1. The saw gin and the roller gin. The saw gin is used for short and medium staple cottons;

8.

The roller gin is used primarily for long-staple cottons.

9.

Baling

After the cotton is ginned it is necessary to package or bale the stock for the purpose of transporting it. The first step takes place at the gin, where the cotton is compressed layer by layer and a cover or jute or cotton bagging is wrapped around and the whole bale secured by six flat strap-iron ties



.

MIXING AND BLENDING

Mixing is the process of intermingling of various verities of cotton, to prepare the raw material for the spinning process. The long continuous filament fibers can't be used for blending because they're too long and too difficult to handle. Also, natural fibers, such as wool and cotton, with which many manufactured fibers are blended, are very short.

Therefore, before blending, man made fibers are first cut into short fibers, called staple fibers. The staple fibers can more easily be twisted with the shorter natural fibers, or with staple fibers of another manufactured fiber.

Staple fibers are created by extruding many continuous filaments of specific denier from the spinneret and collecting them in a large bundle called a "tow". A tow may contain over a million continuous filaments. The tow bundle is then crimped, in much the same way a curling iron is used to crimp a woman's hair, and is then mechanically cut into staple fibers, usually ranging in length from 1 to 6-1/2 inches, depending how they are to be used.

Purposes of Blending

Blending of different fibers is done to enhance the performance and improve the aesthetic qualities of fabric. Fibers are selected and blended in certain proportions so the fabric will retain the best characteristics of each fiber.

Blending can be done with either natural or manufactured fibers, but is usually done using various combinations of manufactured fibers or manufactured and natural fibers. For example, polyester is the most blended manufactured fiber. Polyester fiber is strong, resists shrinkage, stretching and wrinkles, is abrasion resistant and is easily washable. Blends of 50 to 65% polyester with cotton provides a minimum care fabric used in a variety of shirts, slacks, dresses, blouses, sportswear and many home fashion items A 50/50 polyester/acrylic blend is used for slacks, sportswear and dresses. And, blends of polyester (45 to 55%) and worsted wool creates a fabric which retains the beautiful drape and feel of 100% wool, while the polyester adds durability and resistance to wrinkles.

INTRODUCTION OF TWO BASIC CLASSES OF YARN

There are the two basic classes of yarn, namely spun yam and continuous filament yam. Spun yarn is an assemblage of relatively short fibres while continuous filament yarn is a grouping of virtually endless parallel continuous filaments.

In the case of spun yarns, to understand the problem of opening cotton, it is necessary to consider the condition of the cotton in the bale. Due to the way cotton is run into the gin box and then tamped, a cotton bale is made up of a series of sheets or layers. When compressed, these layers become quite firmly necked. Even when the bands are removed from the bale, these layers are very much packed together. In this condition, it is not possible to clean cotton or use it for manufacturing. It must be loosened and separated into small tufts or bunches for further processing.



OPENING AND CLEANING

Opening is the process of tearing apart the compressed and matted cotton until it is very much loosened and separated into small tufts of fiber. Carried to the extreme limit, opening can be the separation of the compressed cotton into its individual fibers. The mechanical opening of cotton is carried on in three different classes of machinery.

1. The opening machines,

2. The picking machines and

3. The carding machines .

The machinery specially designated as opening machinery includes

• Bale breakers,

• Hopper feeders,

• Buckley openers,

• Vertical openers, and

• Horizontal openers .

The purposes of the opening machinery are: first, to open the cotton and, second, to clean it. At the start the opening is paramount and little cleaning is expected, but as the cotton progresses, the importance of cleaning becomes greater. It is difficult to separate opening and cleaning because, until the cotton is opened, it cannot be cleaned. Thus, some mills may consider that opening is merely an incidental feature of cleaning. However, it is necessary to open cotton; regardless of how clean it is, before any suitable fibre arrangement can be made.

So, opening should he considered a separate operation in cotton manufacture.

Types of opening and cleaning

All opening and cleaning machines may be broadly classified in to the following types:

• Loose feeding and cleaning,

• Semi fast gripped and controlled

.

There are three types of opening

1. Hopper type

2. Cylinder type

3. Beater type

In cleaning, the machines may classify based on the following types:

• Major cleaning points

• Minor cleaning points



Blending Feeders

It is a hoper type. There may be three to six blending feeders before the opening line. It purposes is to loosen the closely packed stock making a series of small bunches.

It consists of a hopper with a horizontal endless apron for a bottom and an inclined endless apron carrying many spikes for the front side. An excess of cotton is prevented from passing out by a revolving cylinder covered with spikes near the upper end of the spiked apron. Another cylinder is arranged outside the hopper to remove the cotton carried out of the hopper by the spiked apron. The bottom apron constantly carries the cotton forward against the pinned elevating apron. In this way a supply of cotton is constantly pressed against the pins of the elevating apron. The pins of the apron collect cotton and carry it upward and over the front of the hopper. To prevent an excessive amount of cotton being carried out of the hopper, a spike roll is placed parallel with the elevating apron and not far from it. The spike roll travels in the opposite direction to the elevating apron and so tends to strike off large bunches or any excess of cotton carried by the elevating apron.

When the stock in the hopper becomes a rolling mass, it is carried forward by the bottom apron, upward by the elevating apron and then backward as it reaches the top of the mass or as it is struck down and backward by the spike roll.

The elevating apron moves downward on the outside of the hopper. The pins are inclined downward. Another cylinder, having four or six leather-faced wooden strips across its face, is set parallel with and close to the elevating apron. This '` stripping roll “turns in the same direction as the apron but at a higher surface speed. Consequently the cotton is brushed off the points and drops down to some conveyor which carries it to the next operation.

Under the stripping (or doffing) roll of this feeder, is a series of steel bars over which the cotton passes as it leaves the elevating apron. Below these grid bars is a large space,


NEHRU ARTS AND SCIENCE COLLEGE entirely enclosed, serving as a dead air, dirt collecting section? As the cotton is opened to a greater extent than in the bale breakers, there is a greater opportunity to clean it. While but a small percentage of dirt can be taken out at this place, the cost of removal is very slight.

The hopper of this feeder is enclosed, except for the feed opening just above the bottom apron. A suction fan is mounted on the top of the feeder hopper and draws air from it, thus carrying away dust, fly and dirt which would other wise be carried along with the cotton or throne out into the opening room.

As illustrated in Fig this hopper feeder is supplied cotton through the small hopper at the left. Passing by the swinging automatic door and under the ends of the feelers or rakes, the cotton is carried into the hopper proper. When the hopper is properly filled, the rakes are forced back against the rod girt, which supports them and prevents breaking and bending.

When the rake is against the rod girt, the feeler lever, connected to the end of the feeler shad outside the hopper, operates the micro switch which sends current to the red light

.

Porcupine Opener

It is a beater type opening machine. A Buckley opener is a machine for opening and cleaning cotton with the air of a "Buckley Beater" The objects of this process are first, to continue the opening of the cotton; and second to separate the heavy dirt from the cotton. The

Buckley opener is built around a Buckley beater in a horizontal position. A common Buckley

Dater consists of sixteen circular plates rigidly mounted on a central shaft. There are fillers between the plates to prevent cotton from winding around the shaft; Steel fingers are attached


NEHRU ARTS AND SCIENCE COLLEGE to each plate at uniformly spaced distances. These fingers are bent at different angles so that the entire width of the beater has a uniform distribution of these fingers.

The delivery usually lends to a condenser, or screen section. The simplest type of

Buckley opener feeds the cotton through a pair of feed rolls horizontally in line with the center of the beater, as shown in Fig. 9.2. The cotton is carried downward and forward for about one-half the circumference of the beater and is then discharged approximately; onehalf the circumference of the beater is enclosed by bars

The opening done by the Buckley opener is the result of holding the cotton in the feed rolls, and pulling away bunches with the fingers of the beater. As the fingers are arranged to cover the full width of the feed roll in one revolution, they are constantly pulling at different places and so pulling apart the large bunches of cotton tuft.

Path of Cotton through the Picker (Scutcher)

Breaker pickers and single process pickers are fed with hopper feeders. The feeder is made the same width as the picker, usually 40 inches. The feeder drops cotton on to a short lattice apron which carries it to the picker feed rolls as a continuous, reasonably even flow.

Usually a wooden roll, about 8 inches in diameter, is placed above the apron just back of the feed rolls. This roll presses the loose cotton and prevents it from climbing over the top of the feed rolls, directing it right into the proper position

It is a beater type opening machine. A Buckley opener is a machine for opening and cleaning cotton with the air of a "Buckley Beater" The objects of this process are first, to continue the opening of the cotton; and second to separate the heavy dirt from the cotton.

The Buckley opener is built around a Buckley beater in a horizontal position. A common Buckley Dater consists of sixteen circular plates rigidly mounted on a central shaft.

There are fillers between the plates to prevent cotton from winding around the shaft; Steel fingers are attached to each plate at uniformly spaced distances. These fingers are bent at different angles so that the entire width of the beater has a uniform distribution of these fingers. The delivery usually lends to a condenser, or screen section. The simplest type of

Buckley opener feeds the cotton through a pair of feed rolls horizontally in line with the center of the beater, as shown in Fig. 9.2. The cotton is carried downward and forward for about one-half the circumference of the beater and is then discharged approximately; onehalf the circumference of the beater is enclosed by bars

The opening done by the Buckley opener is the result of holding the cotton in the feed rolls, and pulling away bunches with the fingers of the beater. As the fingers are arranged to cover the full width of the feed roll in one revolution, they are constantly pulling at different places and so pulling apart the large bunches of cotton tuft.

Path of Cotton through the Picker (Scutcher)



Breaker pickers and single process pickers are fed with hopper feeders. The feeder is made the same width as the picker, usually 40 inches. The feeder drops cotton on to a short lattice apron which carries it to the picker feed rolls as a continuous, reasonably even flow. Usually a wooden roll, about 8 inches in diameter, is placed above the apron just back of the feed rolls. This roll presses the loose cotton and prevents it from climbing over the top of the feed rolls, directing it right into the proper position

CARDING

Objects of Carding

• To unwind and open the lap into very small tufts.

• To extract vegetable impurities and all other trash particles from the cotton.

• To open the cotton, even to the separation of one fibre from the all.

• To condense the fibre ioto sliver form.

• To deposit the sliver in to can.

Principle of Carding

There are two main principle of carding.

1. Stripping - Stripping action (Fig 9.4) takes place between cylinder and licker-in.

• The direction of the both licker-in and cylinder wires are inclined in the same direction.

This is called Point to back arrangement.

• Surface speed of the cylinder is about 2000 feet per minute and twice the surface speed of the licker-in.



2. Carding- Carding action between cylinder and flats.

• The wires point in opposite directions. This called point to point arrangement.

• The tufts of cotton down to individual fibres, and remove some short fibres



Path of Cotton through the Card

It will be seen that the fibres pass over the feed plate and are carried downward to the right by the licker-in. This opens up the lap a great deal because the surface speed of the licker-in is in the vicinity of 1000 feet per minute, while the feed roll surface speed is in the vicinity of 1 foot per minute.

The cylinder strips the cotton from the licker-in opposite. The feed plate and carries it upward and over the top to the right. The surface speed of the cylinder is about 2000 feet per minute. As this is about twice the surface speed of the licker-in and, as the points of both the licker-in and the cylinder incline upward, this is a definite "stripping action."

The flats enclose the top of the cylinder, leaving but a very narrow space between the tips of their wire and that of the cylinder. The wires point in opposite directions, thus being arranged for "carding action." This is where the real carding process takes place. The surface speed of the flats is about 3 inches per minute in the same direction as the cylinder. The clearance between the flats and the cylinder is in the vicinity of .010 of an inch. So, the cotton is carded between these two, very close, wire-covered surfaces which separate the tufts of cotton down to individual fibres, and remove some short fibres and dirt to the flats, where they remain.

The slow motion of the flats is used to carry then forward, so that they may be stripped of accumulated fibre and dirt and returned to action. The motion is slow enough so it doe, not affect the carding action but fast enough to prevent loading the flats with too much fibre. Beyond the flats, the cylinder carries the cotton downward to where it is transferred to the doffer. The surface of the doffer moves at a slow speed, averaging around 72 feet per minute, and in the same direction as the cylinder, where they approach each other. The two surfaces are generally set about .007 of an inch apart. The ginner generally considers this a stripping point but a study of the wire arrangement and directions will show that the action is carding.



After making half a turn on the doffer, the fibers come up under the doffer comb. This comb vibrates very rapidly, and, as it moves downward, the points move against the back of the doffer wire, producing a definite stripping action, point of the comb will be about 0.010 of an inch away from the doffer wire. This stripping action removes a thin film of fibres the width of the card.

The web is much too thin to attempt to handle it and so the entire width is carried forward to a funnel-shaped "trumpet," where it is drawn through a small hole by a pair of calendar rolls and "condensed" to a sliver. The fibres retain this rope-like form due to the pressure resulting from passing through the trumpet. It is carried upward and into the coiler.

The coiler is a cast-iron stand attached to the front of the card. It has a foot projecting from one side of the bottom to hold the roving can and a top projecting over the foot with a device for coiling the sliver in a regular arrangement in the can. There is a small trumpet in the top of the coiler, a pair of small calendar rolls to draw the silver through it and a revolving plate gear carrying an inclined tube, through which the sliver passes. The "tube gear" turns, arranging the sliver in a coil in the can. At the same time, the can table turns the can so that each coil is a little to one side of the preceding coil. The result is a series of coils in a spiral, making a regular, compact arrangement in the can from which the sliver may be withdrawn without tangling.

INTRODUCTION OF YARN FORMATION

In a Yarn formation position of a spinning sequence a longitudinal fibre array first is refined in a drafting process, and the refined fibre array then is subject to a twist imparting process, and is taken off the twist-imparting zone as a yarn.

• Drawing out,

• Twisting, and

• Winding of fibers into a continuous thread or yarn.

DRAWING

After carding or combing, the fiber mass is referred to as the sliver. Several slivers are combined before this process. Drawing is the process where the fibres are blended and straightened. Multiple cans of sliver are drawn together at the draw frame to make the resulting sliver more uniform. The number of drawing passages utilized depends on the spinning system used and the end product.

Object of drawing

Doubling

• To feed and combine 6 or 8 card slivers side by side through draw frame to produce one sliver.

• Doubling is the process improves uniformity or regularity of the final sliver by averaging out the weight variation existing in sliver fed to draw frame.



Drafting

• Attenuate the feed sliver until the required size is obtained in delivery sliver.

• Straightening and parallelization of fibre is achieved by drafting rollers.

Condensing

• To condense the thin fleece or web delivered from the front roller into single sliver.

• Deposition of sliver in the form of coils in a can with the help of coiler mechanism.

Principles of drawing

The drawing process is:

• First, to improve the uniformity of the slivers treated and

• Second, to straighten the fibres composing the slivers, malting them more nearly parallel to each other.

A series of rollers rotating at different rates of speed elongate the sliver into a single more uniform strand. The straightening action of roller drawing (Fig 10.1) is the result of holding a large mass of fibres in rolls moving at one speed and pulling away some of the protruding fibres with rolls moving at a higher rate of speed. As adjacent fibres are more or less entangled with each other, increasing the speed of one fibre causes it to drag by the others. The result of having one fibre slip past another is that each tends to cling to the other and the contacting ends are straightened out.

The amount of straightening depends upon how much one set of rolls moves faster than the other set of rolls

Drawing machine functions

The first object, improving the uniformity of slivers, is accomplished by

"doubling." "Doubling" is the practice of feeding two or more strands at once, to produce one strand. It is customary, with different types of drawing frames, to double 4, 6, S or 16 ends, with rare Cases of doubling 5 or 7 ends. In an effort to improve the uniformity, the drawing operation is often repeated. On the theory that if the first doubling improves the uniformity, and a second operation will carry the improvement even further. Two processes of drawing


NEHRU ARTS AND SCIENCE COLLEGE are quite as good as those produce when three processes of drawing are used. So, most mills are using but two processes of drawing. Many mills have reduced drawing to one process.

Using a second process of drawing, directly after the first process, will show a continued improvement in uniformity measured by one yard lengths. But the increase is not as great as during the first drawing.

The second object straightening the fibres and making them more nearly parallel. is accomplished by the draft or roller drawing. As the fibres progressm through the machine; they are drawn along at increasing speeds. As one pair of rolls draws the fibre away from the preceding pair of rolls, the speed of the fibre is increased and it is pulled away from those moving less rapidly.

COMBING

Combing is the process that follows carding in the preparation of fibers for spinning, lays the fibers parallel, and removes noils (short fibers). The modern combing machine is a specialized carding machine. Combing produces a fine sliver suitable for drawing out and spinning into strong, smooth yarn. The process, used for long staple cottons and worsted yarn, is expensive, since up to 25% of the card sliver is eliminated. Combing is an intermittent operation. The shorter fibers, neps and dirt are removed and the fibers are made quite straight and parallel.

Objects

The objects of combing are as follows:

• First, to remove short fibers from the cotton;

• Second, to remove any neps and dirt remaining with the cotton and third to straighten the fibers and so make them parallel to each other.

Degree of Combing

In some cases, combing is classified by the amount of noil removed. Where the percent of noil is not over 10% it is often spoken of as "semi-combing". In these cases, the removal of short fibers is at a minimum and while it improves the quality of the stock, the greatest value of the operation is the straightening of the fibers. "Regular combing", is the term applied to those cases which represent the common procedure, where the noil amounts to between 10 and 20 percent. "Double combing", applies when the combed sliver is taken back to the sliver lapper and put through the combing operations a second time. This is rarely done but when the procedure is followed the noil will be between 20 and 30 percent. It is obvious that the double combing is used only when the highest quality products of the finest counts are desired.

Process detail



For the purpose of detailed study, combing may be considered a series of independent operations, each of which may be studied as an isolated mechanical action, where all are so timed and located that the cotton passes through one after the other as a continuous operation.

If, instead of tying to understand the comb as a whole, the student will, at the start, study each action until familiar with it and then go back and review the entire machine as a summary to all the individual studies, he will fmd that much less time is necessary to thoroughly absorb all the details of the intricate combing process.

The separation of combing into its various actions gives the following list, taking the actions in order of occurrence:

• Feeding which introduces the ribbon laps in a series of short lengths.

• Nipping which grips the fibers between two parallel jaws as a means of holding fibers while the short fibers, neps and dirt are being removed.

• Combing, which passes many rows of closely spaced needles through the fibers held by the nippers, as the means of removing short fibers, neps and dirt

• Detaching, which consists of; (a) moving the previously combed cotton backward sothe newly combed fibers may overlap the others, and (b) drawing those fibers which project the farthest from the lap in the nippers, away from the lap.

• Top combing, which draws the back end of the detached fibers through a row of closely spaced needles, thus straightening and cleaning them and preventing short fibers from being carried along by contact with the long fibers.

• Condensing, which passes the web from the detaching rolls through a trumpet forming it into a sliver.

• Drawing, which passes the slivers from all the heads, as a narrow sheet, through a series of drawing rolls to reduce them to a normal weight of sliver.

1.

Nippers

The nippers, the nipper cam and the connecting levers used in actuating the nippers. The lower nipper, often called the nipper plate, is fixed in position. The upper nipper, often called the nipper knife, rises and falls to cause opening and closing. The position of nipper knife is regulated by moving the frame, as for the nipper plate.

2.

Cylinder Combing

Cylinder combing is the operation in which the comb removes much of the short fibers, neps and dirt. Because of this operation, the cotton fibers are very much straightened.

Cylinder combing consists in passing many rows of fine, closely spaced needles through the fringe of fibers projecting from the nippers.



3.

Top Combing

The function of the top comb is to comb the portion of the fibers held in the nippers during the cylinder combing. As it is impossible for the cylinder to comb the entire length of the fiber, the top comb is located so that it will comb the tail end of the fibers as they are being drawn away by the detaching rolls.

4.

Detaching

The purpose of the detaching mechanism is to grasp the combed fibers which project farthest from the nippers and draw them away, overlapping the previously detached cotton to produce a continuous sheet of fibers

Comb Actions

The feed rolls have just turned forward a short distance, the nipper knife is moving downward and the half lap is nearly ready to start combing. The end of the lap is still in the top comb as a result of the last top combing action, but the last groups of fibers detached have been carried forward until their ends are up in the detaching rolls.

The nippers closed before the combing action started. As they closed, the lap was forced down out of the top comb directly into the path of the needles of the half lap. The top comb and the detaching rolls are still inactive.

After the last needles of the half lap left the cotton, the detaching rolls turned backward a short distance. This caused a thin web of combed fibers to hang down at the back of the steel detaching roll. As the segment came to the leather detaching roll, all three detaching rolls started turning forward. When the segment came in contact with the leather roll, it lifted it, and these two parts grasped the most forward fibers. These fibers being drawn from the lap and being led on to the previously detached cotton, thus forming the "piecing".



As the fibers are being detached from the lap held in the nippers, the pull of the detaching rolls causes the lap to form a nearly straight line from the feed rolls to the bite of


NEHRU ARTS AND SCIENCE COLLEGE the detaching roll and segment. This causes the fibers which are being detached to pass \ through the needles of the top comb and so provides the top combing action. Meanwhile, fibers not actually gripped in the detaching bite are retarded from passing forward by the friction in the top comb. Any fibers tangled with or adhering to fibers being detached either are not drawn forward or are collected in a crumpled up form behind the top comb.

ROVING

In preparation for ring spinning, the sliver needs to be condensed into a finer strand, known as a roving, before it can be spun into a yarn. Because ring spun yarn is made in a linear process (sliver to roving to yarn), the yarn is stronger. The sliver is fed through a machine called the roving frame, where the strands of fiber are further elongated and given additional twist. These strands are called the roving.

Object

The main object of speed frame:

• Drafting: To reduce the thickness of material and parallelization to make the product more even.

• Twisting: To import twist to the material.

• Winding: To wind the rove on the bobbin.

• Building: To build the material on the bobbin in a suitable shape

(Cylindrical body with conical edges)

Common names

These were commonly named as follows:

1. Slubber

2. Intermediate (First Intermediate)

3. Fine (Fly Frame, Speeder, Second Intermediate)

4. Jack

The term "fly frame" is frequently applied as a general term for all roving frames but is also used for the specific ope r at i on listed here as a fine frame.

Operation on Roving Frame

The work of a roving frame may be divided into a number of separate operations, each of which is almost independent of the others and yet so timed and tied in with the others that the whole makes a unit. These operations and their objects are:

• Drawing, to reduce the size of the strand.

• Twisting, to give the necessary strength.

• Laying, to put the coils on the bobbins in a regular arrangement.

• Winding, to put successive layers on the bobbins at the proper rate of speed.



• Building, to shorten successive layers to make conical ends on the package of roving.

1. Drawing

As the basic ideas on which all of the roving drafting equipment works are still those of the regular, three roll system, this section treats, fast, of the regular draft equipment, after which various systems for long draft are considered. The object of drawing, in the roving process, is to reduce the bulk of the strand to a suitable size for spinning.

2. Twist

Twisting, in roving, is the operation of revolving the strand about its own axis so that the fibres are arranged in a spiral form and thus bind each other together.

The object of using twist in roving is to give the strand sufficient strength to withstand the strain of turning the bobbin on which it is wound, in the creel of the next operation. Unfortunately, as the strand is drawn on the roving frame, its bulk is so reduced that it has practically no strength.

Consequently, if the strand is to be unwound through Cunning the bobbin by pulling on the roving, the strength must be materially increased. The purpose of twisting is limited to this one phase of the problem. As increased twist reduces the productive capacity of the machine, it is generally used in as limited quantities as possible.



Twisting is accomplished by the "flyer", (Fig 10.3) which is carded on the spindle. As the strand is delivered at the front rolls, it is led downward and forward to the top of the flyer, through the flyer and on to the bobbin. The flyer revolves rapidly and carries the roving around with it. The result is that the front roll is delivering a narrow ribbon of fibers in a fixed plane; the flyer, holding the other and of the exposed strand, turns rapidly and twists it. The twist runs quickly up to the front roll as t h e is nothing to prevent. As rapidly as the front roll delivers a new length of ribbon, the flyer makes additional turns and they run back to the front roll. For any given condition, the flyer speed and the front roll speed are fixed, which gives a constant ratio between the turns of twist and the inches delivered at the front roll.

This is the 'Twists per Lich".



In all modern frames, there are two lines of spindles directly in front of, and just below the drawing rolls. The two lines of spindles are staggered to reduce floor space necessary and to make it easier to leach the back line. The spacing of spindles is, given as the

"space" of the frame, which is the distance between spindles of one line, measured from center to center. Another way of classifying the spindle spacing is by the "gauge", which is the distance for a given number of spindles, including both front and back spindles. While this seems a very arbitrary figure to the beginner, it will soon be seen that the distance in inches is from center to center of roll stands and that the number of spindles is the number supplied by one section of the front roll.

4. Lay

Lay refers to the arrangement of the coils of roving wound around the bobbin in any given layer. The lay may be "close" or "open", depending upon whether succeeding coils are


NEHRU ARTS AND SCIENCE COLLEGE crowding each other or are so spaced that they do not touch. The closeness of the lay is measured in "coils per inch", which means just what the expression says: - the number of coils that are wound around the bobbin, in any one layer, in the distance of one inch parallel with the axis of the bobbin.

The object of the laying operation is to put the successive coils of roving side by side in a regular, uniformly spaced arrangement, which forms a helix around the previously built package. The problem is somewhat increased by the continually increasing diameter of the bobbin, as layer after layer is put on, making each successive layer on a different diameter.

SPINNING FRAME

The ring frame was invented in 1828 by the American John Thorp and is still widely used today. This system involves hundreds of spindles mounted vertically inside a metal ring. Many natural fibers are now spun by the open-end system, where the fibers are drawn by air into a rapidly rotating cup and pulled out on the other side as a finished yarn.

The predominant commercial systems of yarn formation are ring spinning Fig 10.5 and open-end spinning. In ring spinning, the roving is fed from the spool through rollers.

These rollers elongate the roving, which passes through the eyelet, moving down. The traveler moves freely around the stationary ring at 4,000 to 12,000 revolutions per minute.

The spindle turns the bobbin at a constant speed. This turning of the bobbin and the movement of the traveler twists and winds the yarn in one operation.

Object of Ring frame

The spinning frame may perform four basic operations. Each is continuous and all are carried on simultaneously. These operations are as follows: -

• Drafting: reducing the bulk of the strand to the desired size. (In a few instances, mostly for waste yams, drawing may not take place).



• Twisting: causing the fibers to spiral around each other and bind themselves together to give the desired strength.

• Winding: coiling the twisted strand of yam around the bobbin as rapidly as it is delivered by the drafting rolls.

• Building: regulating the pattern of winding of the yam to give a package of a desired shape and size to suit the requirements of the use of the yam.

While each of these operations will be considered separately, it is important to keep in mined the relationship of each to the others.

Passage of Material through Ring Frame:

The supply package, roving bobbins are placed in this creel with the help of the skewers as shown in Fig 10.5. In modern frame instead of this type, umbrella creels are used.

The roving from each bobbin is drawn outward and downward through a roving guide and through a traversing guide by the movement of the back pair of draft rollers. The purpose of traversing guide is to allow the material to the full width of the roller, so as to avoid the damage to the drafting rollers.

The roving strand passes through the back pair, middle pair and finally through the front pair, gets drafted thus results a ribbon of fibres without any twist. As soon as the fibre emerges from the front rollers, they are twisted together by the rotation of traveler and are pulled downward at sharp angle through the yarn guide (lappet guide) which is directly over the centre of the spindle and the cop.

The yarn then passed about vertically downward to the traveler on the ring where it makes approximately right angled turn to pass horizontally to the cop. Between the yarn guide and the cop and yarn is revolved by the rotation of the traveler on the surface of the ring and gets twisted.

The spindles are driven by the tin roller. The tin roller in turn receives the drive form the motor. Each spindle is separated by a device called separators (thin metal plate of steel or aluminum). This is to avoid lashing of ends by the ballooning effect. The yarn thus wound on the bobbin is made to required shape by suitable lying mechanism.



INTRODUCTION OF YARN

Yarn is a long continuous length of interlocked fibers, suitable for use in the production f textiles, sewing, crocheting, knitting, weaving, embroidery and open making.

Thread is a type of yarn intended for sewing by hand or machine.

The characteristics of spun yarn depend, in part, on the amount of twist given to he fibers during spinning. A fairly high degree of twist produces strong yarn; a Low twist low twist produces softer, more lustrous yarn; and a very tight twist produces crepe yarn

.

DEFINITION

Yarn consists of several strands of material twisted together. Each strand is, in urn, made of fibers, all shorter than the piece of yarn that they form. These short fibers are spun


NEHRU ARTS AND SCIENCE COLLEGE into longer filaments to make the yarn. Long continuous strands may only require additional twisting to make them into yarns.

11.2.1 Types of Yarns

Staple (spun) yarn -made from short, staple fibers that must be held together by some earns (usually twisting) in order to be formed into a long, continuous arn. Natural fibers except silk are staple fibers; manufactured fibers and silk re usually filament but can be cut into staple lengths.

Filament - made from long, continuous strands of fiber. (May be monofilament r multifilament). Silk and manufactured fibers come in filament form.

CLASSIFICATION OF YARN

Yarns are also classified by their number of parts.

• Single yarn - made from a group of filaments or staple fibers twisted together; if untwisted, it will separate into the individual fibers

• Ply yarn – (Fig 11.1)two or more single yarns are twisted together to make a ingle yarn; if untwisted, it will separate into the single yarns which will separate into individual fibers

2-Ply and 3-Ply Yarns

• Cord yarn –(Fig 11.2) two or more ply yarns are twisted together; if untwisted, it will separate into the plied yarns which will then separate into ingle yarns which will separate into individual fibers.

• Novelty (fancy, complex) yarns - yarns that have a decorative effect; not uniform in size and appearance.

• Core-spun yarns - yarns that have a central core of one fiber around which s wrapped or twisted an exterior layer of



Yarn Twist

Direction of twist

When fibers are wisted to make a yarn, they are twisted to the right or left. This twisting is called S or Z twist. Most yarns are made with a Z twist. The direction f twist does not usually affect the characteristics of the yarn or fabric.

Z- and S-twist yarn

Twists per inch

The number of twists per inch can, in plied yarns, be determined by counting he number of bumps in one inch, and divide by the number of singles (the strands plied together to make the yarn).



In the industry the number of twists per inch is calculated as

• Where, T.M. is Twist multiplier or K (twist factor).

• Twist factor has been established by experiments and practice that the aximum strength of a yarn is obtained for a definite value of K.

Amount of twist

Twist is needed in yarn to hold the fibers , and is added in both the pinning and plying processes. The amount of twist varies on the fiber, thickness of yarn, preparation of fiber, manner of spinning, and the desired result Fine wool and silk generally use more twist than coarse wool, short staple more than long, thin more than thick, and short drawn more than long rawn.

The amount of twist in a yarn helps to define the style of yarn- a yarn with a lot ofair such as a woolen yarn will have much less twist than a yarn with little air, like a worted yarn.

It also affects the stretchiness of the yarn, strength, the halo ofthe yarn, and many other attributes. Filling or weft yarns usually have fewer twists per inch because strength is not as important as with warp yarns, and highly twisted yarns are, in general, stronger. Warp yarns have to be stronger so that they can withstand the tension o the loom.

The amount of twist affects the characteristics and properties of a yarn including appearance behavior and durability.

• Generally, higher twist creates yarns that are

Stronger

More firms

Smaller in diameter

Smoother

Resistant to snagging and abrasion

Resilient

Good conductors of heat

• Generally, lower twist creates yarns that are

Weaker

Softer

Larger in diameter

Fuzzy

Prone to snag and abrade

Crush easily



Resistant to heat transfer

Filament yarns often have little or no twist because they are continuous and stronger the bars will not break or separate from the yarn as easily as spun (staple )yarns

COMPLEX (FANCY, NOVELTY) YARNS

• Complex yarns are made to create decorative effects in the fabrics into which they are woven.

• Usually weaker than simple yarns.

• Usually woven into the filling direction of the fabric.

• Yarns usually exhibit more snagging and wear.

• These are yarns that differ from normal yarns, in appearance, texture and handle

• They constitute a vast range of types, many specifically designed for hand knitters

Novelty yarns can be further split into two categories, fancy and metallic yarn.

Fancy yarns

• Fancy yarns can be made from staple or filament fibres.

• They are intentional produced to have a distorted or irregular construction.

• Popular effects include knops, snarls, loops and slubs.

Metallic yarns

• Usually produced from aluminium sheets laminated with plastic film, cut into thin ribbons.

• Or can be core spun, for example a polyester core with a metallic outer.

11.4.1 Main parts of fancy yarn:

There are three main parts are involved in the fancy yarn.

1. Core (ground) yarn

2. Effect yarn

3. Binder yarn



• Novelty, fancy and decorative yarns are used in both woven and knitted fabrics.

• Knots, snarls, loops and other irregularities can be introduced to create textured surface effects.

• Fancy yarns usually have a base or core yarn which is a conventional plain yarn, this yarn is combined with the effect yarn shown in

• The effect yarn can be held in place with a binding yarn.

Types of Fancy Yarn

There are many types of fancy, novelty and decorative yarns produced. They can be produced in many ways.

• Different coloured fibres can be blended together then spun as one yarn.

• Colour can be applied by printing or dyeing pattern onto roving or yarn.

• Spots of coloured fibre can be twisted in with the base yarn.

• Two or more threads of different, softness, thichness, weight, colour or fibre content can be twisted together.

• Raised textures can be introduced by controling the amount and direction of twist.

• Fancy yarns can be natural or man-made or a combination of both.

1.

Boucle, gimp and loop yarns (Fig 11.5)

These yarns are made by feeding one or more effect yarns faster than the core yarn while spinning



• Boucle has a hard twisted core yarn; the effect yarn is rapidly twisted round the core so that excess yarn forms an irregular wavy, bumpy surface

• Gimp is much the same as boucle, but the excess yarn forms a more regular surface

• Loop yarn is the result of the excess soft spun yarn being formed into well shaped circular loops on the hard spun core

2. Snarl yarns

• Snarl yarns are made in a similar way to loop yarns

• Except the effect yarn has a high, lively twist, so that the excess bits snarl and double up on themselves and twist together

• Just like the lengths of cord we make on a door-knob

3. Knop or button yarns

• Just like the lengths of cord we make on a door-knob

3. Knop or button yarns

• These yarns are also made by feeding the yarns at different rates while spinning

• But this time the excess yarn of one or more of the components forms bunches

• These can be at regular or irregular intervals



5.

Slub yarns

• Slub yarn is charactorised by having, alternating short places of thin, firm twist yarn, with places of very thick, loose twist yarn

• The differnt areas can be at regular or irregular intervals

6.

Marl yarns

• Marl yarns are made by twistng together two or more ends of different coloured yarns

• The effect pattern is one of regular diagonal stripes of each colour

7. Spiral and corkscrew yarns

• These are plied yarns where one yarn wraps around the other, rather than the yarns being twisted together

• A spiral yarn has a higher twist than a corkscrew yarn

• A spiral yarn usually has a thinner yarn wrapped round a thicker core

• A corkscrew yarn has a softer bulkyer yarn wrapped round a thin, firm yarn

8. Chenille yarns



• Chenille yarns have a soft, fuzzy cut pile which is bound to a core

• These yarns can be spun, but the machinery required is much specialized

• For this reason, these yarns are usually woven on a loom

• The effect yarn forms the warp, which is bound by a weft thread

• The weft thread is spaced out at a distance of twice the required length of pile

• The warp is then cut half way between each weft thread.

SEWING THREAD

Sewing thread is found everywhere, in common apparel, home furnishing, sports wear and shoes, in automotive items like air bags and seat belts as well as in various other technical applications. The sewing seam performances of the sewing thread are influenced by material to be sewn, sewing techniques and the end use desired.

Sewing thread functions

Sewing thread covers two main functions; the most important is obviously joining the different fabrics and give the product the necessary strength in the area of its highest stress – the invisible seams. The second function is refining products with decorative stitching. In both cases one thing is often underestimated: Sewing Thread may account only for 0,5% of fiber amount within a garment, however, it shares fairly more than 50% of responsibility for the final quality of a garment.

The requirements can be defined as:

• The ability of sewing thread to meet functional requirements of producing desired seam effectively.

• Ability to provide desired aesthetics and serviceability in the seam.

• Cost of the sewing thread and that of resultant seam.

Sewing thread availably

Sewing thread is available as:

• Spun yarn (Cotton or PES spun)

• Core spun (PES/Cotton; Poly/Poly)

• Flat filament threads (PES, Nylon, etc.)

• Textured filament (Draw-textured or air-textured)

• Special threads mainly for technical applications

Sewing thread properties

1. Functional requirements

Tensile properties : Sewing thread should have high tenacity with moderate tension.

For better loop formation characteristics, the elastic modulus of the sewing thread should be high.



Friction: There should be uniformity of friction over long length. Factors are responsible for giving maximum possible tension fluctuation of the yarn components in the cross section and the length.

Passage through needle eye: There should be no sudden shocks when thread passes through the eye of the needle. Needle temperature is critical for sewing thread of man made fibres.

Free from knots and faults: Sewing thread should be free from knots and faults to give smooth performance.

2. Serviceability

During sewing, threads are subjected to abrasion over needles and fabric threads.

There is a lose of strength during and after sewing during fabric use. Sewing thread should have high abrasion resistance so that lose strength is minimum. For a good serviceability, seam must be firm. A seam strength test could be performed. Different stitches are applied to different application. Fabric properties affect seam strength along with loop and abrasion strength of sewing thread and the amount damage due to sewing. To avoid puckering of garments around the seams, the thread shrinkage should be generally less then 2% during washing.

3. Aesthetic

Colour, shade, luster, smoothness, fitness are some of aesthetic related characteristics of sewing threads. Certain amount of hairiness in sewing thread has to positive effect on sewing but this effect has to be sacrificed for appearance. There is a tendency to use dyed sewing thread for appearance.

7.

Cost consideration

From the raw material aspect, sewing thread of natural silk is expensive. A higher melting sewing thread may be expensive. but, it should have a judicious use in the sense that the fabric for which it is used should also have a high melting points as the hot needles not only attack the sewing thread but the fabric also.

8.

Other sewing thread properties

In addition to the essential properties, some of the applications may be required for sewing threads to have special properties like, resistance to flexing in seams in shoes, discontinuous surface to provide grip and avoid slippage in the seam for high seam strength applications.




1.

Explain the process of Spinning –Definition ,Classification – Chemical and mechanical

2.

Write in details about spinning –blending, opening, cleaning, doubling, carding, combing, drawing ,roving ,spinning.

3.

what are all the classification of Yarn– definition , classification – simple and fancy yarns

4.

Give in detail about the Sewing threads and its properties.




STUDY MATERIAL


SEMESTER : II


UNIT : IV

SYLLABUS

Wovens- basic weaves –plain, twill, satin.

Fancy weaves- pile, double cloth, leno, swivel, dobby and jacquard.

___________________________________________________________________________

INTRODUCTION

Woven fabrics are classified as to weave or structure according to the manner in which warp and weft cross each other. The three fundamental weaves, of which others are variations, are the plain, twill, and satin.

Weave representation

The fabric weave or design is the manner in which the warp and filling are interlaced.

The pattern or repeat is the smallest unit of the weave which when repeated will produce the design required in the fabric. There are many ways of representing a weave, a most familiar method being to use square design paper. The use of thread diagrams and cross-sections is another effective method of representation.

On the design paper, the vertical rows of squares represent warp ends and the horizontal rows of squares represent filling picks. A mark in a small square indicates that at this particular intersection, the warp end is shown of the face of the fabric with the pick beneath. It is normal to use a filled in square to indicate that the end is over the pick and a blank square to indicate that the pick is over the end.

BASIC WEAVES

Three basic weaves are,

1. Plain,

2. Twill, and

3. Satin.

Plain weave

In plain weave the warp and weft are aligned so that they form a simple crisscross pattern. Each weft thread crosses the warp threads by going over one, then under the next, and so on. The next weft thread goes under the warp threads that its neighbor went over, and


NEHRU ARTS AND SCIENCE COLLEGE vice versa. Plain weave is also known as "tabby weave" or "taffeta weave." From fig15.1 it can be seen that the plain weave repeats on 2 ends x 2 picks.

Plain fabric comprises a high percentage of the total production of woven fabrics and it can be produced on a loom with 2 harnesses. It has the highest number of interlacing as compared with other weaves and therefore it produces the finest fabrics.

Ornamentation of Plain Cloth

The appearance of a plain fabric can be changed in many ways, which can be summarized as follows:

1. The use of color

In the warp direction color stripes are produced along the length of the fabric; in the filling direction, color stripes are produced across the width of the fabric.

We used in both warp and filling directions a check effect is produced.

2.

Changing Yarn and Fabric Counts



Stripes and check effects can be produced by using different fabric count or yam count in one or both directions. Also rib effects can be produced by using different yarn counts and different tensions.

3. Changing the Yarn Twist

Using combinations of different twist levels and directions in the warp or filling (or both warp and filling), different effects can be produced in the fabric due to the changes in orientation of the fibers. Also different amounts of twist produce different shrinkage characteristics in different parts of the fabric and so change the appearance.

Variations of the Plain Weave

Some fabrics are considered to be derivatives of the plain weave. These are, in effect, extensions of the simple interlacing and, like plain weave; they can be produced on a loom with two harnesses.

1. Warp Rib Weave

In this the extension of the plain weave is in the warm drection, as shown by; the warp weaves in the same order as in the plain fabric, namely, every two adjacent ends weave opposite to each other.



In this case groups of ends are woven with each group in direct opposition to the adjacent groups. The repeat is always on 2 picks x any number of ends as shown in Figure

15.3. The ribs produced in the fabric run in the direction of the warp. It is usual to use coarse warp and fine filling to emphasize the rib. The fabrics are normally stronger than the plain fabrics because of the low crimp level.

3. Basket Weave (Matt Weave)

In this weave the extension is made in both directions so that groups of ends and picks are woven in the same way as single ends and picks are woven in the plain weave. The weave is denoted in the manner used for rib weaves, i.e. as 2 up 2 down basket or 2 x 2 baskets

Twill Weave

It is made by passing the weft threads over one warp thread and then under two or more warp threads, over one and under two or more, and so on, with a "step" or offset between rows that creates the characteristic diagonal pattern. Because of this structure, twills generally drape well. Examples of twill fabric are chino, denim, gabardine, tweed and serge.

Twill Weave, the second basic weave, is characterized by diagonal lines running at angles varying between 15° and 75°. A twill weave is denoted by using numbers above and below a line (such as 2 up 1 down twill). At Figure 15.5 the 2 up 1 down twilll and the Figure

15.6 the 1 up 2 down Will are shown; these represent the smallest possible repeat of twill weaves, and one is the opposite side of the other. The repeat is always on a number of ends and picks equal to the addition of the two numbers above and below the line denoting the weave. A 2 up 1 down twill or a 1 up 2 down twill repeats on 3 ends x 3 picks. If the number above the line is greater than the number below the line, the weave is known as warp face twill. If the opposite is true, it is filling face twill. There is a third alternative in which the number of above and below the line are equal (such as 2 up 1 down twill); this is called balanced twill. Most twill fabrics are made with warp face weaves



The twill weave is always given a direction; a right-hand twill is one in which the twill line runs from bottom left to top right and a left-hand twill is one in which the twill line runs from bottom right to top left. The angle of the twill is determined by the amount of shift in the points of interlacing. A twill weave when has more than one pick shift and one end shift is called steep twill; if the shift is more than one end and one pick it is called a reclining twill. A steep twill will have twill angles more than 45° and a reclining twill have angles less than 45° as shown in Fig15.6. However, the angle of the twill line in the fabric depends on the number of picks and ends/in. in the fabric. A 45° twill woven with the same yarn in warp and filling,



Satin and Sateen Weaves

This is the third basic weave, in which the interlacing points are arranged in a similar way to twill weaves but without showing the twill line. The satin weave is a warp face weave and the sateen is a filling face weave. Sateen are sometimes called filling satins weave.

Figure 15.7 shows a 5-ends (or 5 harness) satin and Figure 15.8 shows 5-end sateen. In this case, the repeat is on 5 ends x 5 picks and it is clear that one design is the backside of the other. There are two different ways of arranging the interlacing points, one by using a counter (or move number) of 2 picks and the second by using 3 picks as counter. It can be seen that in warp face satin the ends float over all the picks but one in the repeat. The interlacing can be arranged to be in the right-hand direction or in the left hand direction as shown in Figure 4.7(b).For every number of ends and picks in the repeat there is more than one arrangement for the interlacing points.



Although the satin weave is the backside of the sateen weave produced on the same number of harnesses, it is not tine to say that the fabric produced as a satin can be used as sateen. This is mainly because for a satin fabric to be smooth and lustrous, the ends/inch must be higher than the picks/in., but the opposite is true for sateen fabrics. The sateen fabrics we normally softer and more lustrous than satins, but satins are usually stronger than lateens. In both fabrics, if a heavy construction of filament yarns is used, the fabric tends to be stiff and does not drape easily. However, the length of the float can balance the effect of the construction, but longer floats have disadvantages in that they have an adverse effect on fabric serviceability. Long float satins and lateens are useful in jacquard designing or in combination with other weaves, bur are rarely used elsewhere.

INTRODUCTION OF FANCY WEAVES

The three fundamental weaves, of which others are variations, are the plain, twill, and satin. Pile fabrics have an additional set of yarns drawn over wires to form loops, and may be cut or uncut. Warp-pile fabrics include terry and plush; weft-pile, velveteen and corduroy. In double-cloth weave two cloths are woven at once, each with its warp and filling threads, and combined by interlacing some yarns or by adding a fifth set. The cloth may be made for extra warmth or strength, to permit use of a cheaper back, or to produce a different pattern or weave on each surface, e.g., steamer rugs, heavy over coating, and machine belting. Velvet is commonly woven as a double cloth. In swivel weaving, extra shuttles with a circular motion insert filling yarns to form simple decorations, such as the dots on Swiss muslin. Figure weaves are made by causing warp and weft to intersect in varied groups.

Simple geometric designs may be woven on machine looms by using a cam or a dobby attachment to operate the harnesses. For curves and large figures each heddle must be separately governed. The Jacquard loom attachment permits machine weaving of the most complicated designs.

PILE WEAVE

Pile weave is a form of textile created by weaving. Pile fabrics used to be made on traditional hand weaving machines. The warp ends that are used for the formation of the pile


NEHRU ARTS AND SCIENCE COLLEGE are woven over metal rods or wires that are inserted in the shed (gap caused by raising alternate threads) during weaving. The pile ends lie in loops over the inserted rods. When a rod is extracted the pile ends remain as loops on top of the base fabric. The pile ends lying over the rod may be left as 'loop pile', or cut to form 'cut pile' or velvet.

On mechanical looms the technology of 'wire weaving' still exists, using modern technology and electronics. This weaving technique allows users to obtain both loop pile and cut pile in the same fabric. Other techniques involve the weaving of two layers of fabric on top of each other, whereby the warp ends used for the pile are inserted in such a way that they form a vertical connection between the two layers of fabric. By cutting the pile ends in between the two layers one obtains two separate pile fabrics. With this technique only the cut pile effect can be obtained. This is known as 'face-to-face weaving'. Both 'wire weaving' and

'faceto- face' weaving are used for the manufacturing of upholstery and furnishing fabrics as well as in rug making.

Warp pile

In warp pile fabrics the face effect is produced by raising an extra warp above the ground fabric in a series of loops. If the loops are uncut, the fabric is called terry cloth. Bath toweling is a familiar form of terry cloth. If the loops are cut and the fibers stand erect from the ground, then the pile characteristic of velvet is formed. In double shuttle looms, two fabrics are woven one over the other face to face. The raised warp pile surface is formed by holding the two fabrics apart as they are woven with gauge wires and cutting the pile ends which interlace between the two fabrics. Figure 16.1 (A) and (B) illustrate cross sections of a double plush fabric before and after cutting.



Velvet

Velvet is a rich looking, fairly light weight cut pile material used chiefly for dresses, hats and trimmings. Plush is much like velvet but the pile is longer and coarser and it is usually a heavier material used for upholstery, robes and caps.

Plush upholstery material is often designed so that the pile stands out as a pattern.

Examine any plush upholstery material to get a general idea as to the depth and body of the pile. Silk, rayon, mohair, cotton, and combinations of these are used in weaving velvet and plush.

Weft pile

Fabrics are woven with an extra filling are called weft pile

Velveteen and Corduroys

These fabrics are woven with an extra filling which may be arranged 1 ground, 2 piles; 1 ground, 3 piles; or greater preparation. The ground filling weaves with the warp to form the cloth is woven to produce the raised surface. The fabric is then brushed and sheared to form the characteristic soft velvet faced surface.

Plain weave, filling rib weaves, and small twill weaves are generally used for the ground interlacing. Velveteen pile weaves are based on plain and twill weaves with raisers indicated on alternate ends. Corduroy pile weaves are based on plain weave on consecutive ends which may be reversed on alternate cords to form a rounded appearance. The width of the cords is varied by changing the space between the stitching points of the pile weave.

Corduroys and velveteen are made of cotton or of cotton and rayon mixtures. The corduroys are warm, long wearing and comparatively inexpensive so they are widely used for boys clothing, men's suits and trousers and for coat linings where warmth is important.

DOUBLE CLOTH

Double cloth or double weave (also double cloth, double-cloth) is a type of woven textile in which two or more sets of warps and one or more sets of weft or filling yarns are interconnected to form a two-layered cloth. The movement of threads between the layers allows complex patterns and surface textures to be created.

In contemporary textile manufacturing [2], the term "double cloth" or "true double cloth" is sometimes restricted to fabrics with two warps and three wefts, made up as two distinct fabrics lightly connected by the third or binding weft, but this distinction is not always made, and double-woven fabrics in which two warps and two wefts interlace to form geometric patterns are also called double cloths.



Double-faced fabrics are a form of double cloth made of one warp and two sets of wefts or (less often) two warps and one weft. These fabrics have two right sides or faces and no wrong side, and include most blankets, satin ribbons, and interlinings.

These weaves are used chiefly in the manufacture of woolen and worsted suiting and over coating. A double cloth consists of two independent fabrics woven one on top of the other and may or may not be stitched together. In fabrics woven for increased thickness and weight, the two clothes are stitched by having the back warp interweave with the face filling or by having the face warp interweave with the back filling or a combination of both. When arranging these weaves on design paper, face warp and filling threads are treated separately from the back warp and filling threads. A perfect stitch must be made if possible to cover the stitching points.

Rules for Arrangement of Perfect Stitching

• A back end may be raised over a face pick between two raiser of the face weave and next to a raiser of the back weave. This is called a raiser stitch.

• A face end may be lowered under a back pick between two sinkers of the face weave and next to a sinker of the back weave. This is called a sinker stitch.

LENO

In gauze and leno weaving certain ends - termed crossing ends – are passed from side to side of what are termed standard ends, and are bound in by the weft in these positions. The crossing and standard ends may be arranged with each other in various proportions, as 1-and-

1, 1-and-2, 1-and-3, 2-and-2, 2- and-3 etc., but an essential condition is that each group of crossing and standard ends must be placed in one split of the reed. A crossed system of interlacing can be obtained when the entire warp is brought from one beam, and in some cases this is essential in order to produce the desired effect.

Very frequently, however, effects with such a difference in the take up are produced that it is necessary for the two series of ends to be brought from separate beams. The warp may consist entirely of crossing interlacing alternately with straight interlacing in any required order. There is, therefore, almost unlimited scope for the production of variety of effect in striped, checked, and figured fabrics by combining gauze or leno with practically any other system of interweaving.

The fabrics produced by this method are employed for curtaining, shirting’s and for blouse and dress materials as well as for various industrial uses such as filter cloths, screens and sieves. Their great merit lies in a very considerable stability of the interlacing combined with its open nature. The size of the interstices can be determined precisely and will remain stable and uniform even under a degree of pressure.



SWIVEL

The term swivel is sometimes applied to the type of loom in which several narrow fabrics, such as hat-bands, ribbons, tapes, etc., are independently formed alongside each other. In this machine a separate shuttle is employed for each fabric, but there is no fly shuttle, and the goods are not generally described as small wares.

In broadloom swivel weaving, however, a number of small shuttles work in conjunction with an ordinary fly shuttle, the latter inserting a ground weft which forms with the warp a foundation cloth upon which the swivel shuttles produce figures in extra weft. The chief purpose of the swivel arrangement is to produce the ornament with the least possible waste if the extra yarn. Each figure, and in some cases each part of a figure in a horizontal line of the cloth, is formed by a separate shuttle; the extra weft thus being introduced only where required, with little material extending between the figures on the reverse side of the cloth. In addition to the great saving of the figuring yarn, the swivel method has the advantage over the ordinary system of extra weft figuring that each shuttle may control a distinct colour, while the figures have a richer and fuller appearance on account of the weft being thrown more prominently on to the surface. The addition of the swivel mechanism, however, makes the loom much more complex, consequently there is reduced speed and output. The cloths are woven wrong side up, and there is, therefore, the disadvantage that defects caused by broken threads more readily escape observation; but, on the other hand, weaving the cloths right side up would necessitate the bulk of the warp being raised on the swivel picks.

Compared with lappet figuring, in which the floats of a thread cannot be stitched between the extremities, swivel figuring produces much neater effects, as any for of weave development can be applied to a figure. Effects are readily produced, that appear and handle very similarly to styles in which the pattern is formed after weaving by embroidery.

DOBBY

A Dobby Loom is a type of floor loom that controls the warp threads using a device called a dobby. Dobby is short for "draw boy" which refers to the weaver's helpers who used to control the warp thread by pulling on draw threads.

Fabrics requiring more than six harnesses to weave are usually provided with dobby looms. Dobby looms are used for the production of fancy goods, fancy shirting’s; terry towels, handkerchiefs. Dobby looms are equipped with a dobby head mechanical for controlling the movements of the harnesses. The dobby head consists of a series of levers each lever operated independently so that it can raise or lower its harnesses on any pick without reference to other harness lever. Dobbs looms are built for sixteen, twenty-five and thirty harnesses.



JACQUARD

Jacquard is the term applied to a machine invented by Joseph Marie Jacquard, a mechanic of Lyons, France for the purpose of providing looms with a superior head motion.

With the invention of the jacquard, it is possible to have an innumerable number of interlacing in a fabric, because. On a jacquard machine, each warp end is controlled independently of the others.

Cardboard cards are used with perforations in the card to control the operation of the interlacing of each warp end. Thus, the field of designing intricate and novel cloth fabrics is extended so as to permit the duplication of practically on design in cloth.

Types of Jacquards

Jacquard machines while operating on the same principles and essentially the same in construction are divided into different types according to their uses.

• The American index jacquard is used in the manufacture of rugs.

• The French index jacquard is the most common type as this machine is used extensively in many different textile mills and fulfills the average requirements in jacquard weaving.

• A Fine index jacquard is a type often used, especially in the silk and rayon industry, when a large number of warp ends are to be woven. The fine index jacquard is like the French index.

Only more compact, and contains a greater number of hooks; that is, it is capable of controlling a greater number of warp ends.




1. Explain the process of weaving.

2. Write about the classification of basic weaves –plain, twill, satin.

3. Write about the Fancy weaves- pile, double cloth, leno, swivel, dobby and jacquard.




STUDY MATERIAL


SEMESTER : II


UNIT : V

SYLLABUS

Non-Wovens- felting, fusing, bonding ,lamination ,netting, braiding and calico,tatting and crotcheting.

___________________________________________________________________________

INTRODUCTION OF NON WOVENS

Non wovens are a class of textiles/sheet products, unique in industry, which is defined in the negative; that is, they are defined in what they are not. Nonwovens fabrics are different than the conventional textile fabrics and paper. Nonwovens are not based on yarns and (with frequent exceptions) do not contain yarns. They are based on webs of individual fibers. Nonwovens are different than paper in that nonwovens usually consist entirely or at least contain a sizeable proportion of long fibers and/or they are bonded intermittently along the length of the fibers. Although paper consists of fiber webs, the fibers are bonded to each other so completely that the entire sheet comprises one unit. In nonwovens we have webs of fibers where fibers are not as rigidly bonded and to a large degree act as individuals

FIBERS USED IN NON WOVENS

Fibers are the basic element of Nonwovens. Manufacturers of Nonwovens products can make use of almost any kind of fibers. These include traditional textile fibers, as well as recently developed hi-tech fibers. The selection of raw fibers, to considerable degree, determines the properties of the final nonwoven products. The selection of fibers also depends on customer requirement, cost, process ability, changes of properties because of web formation and consolidation. The fibers can be in the form of filament, staple fiber or even yarn.

The following table shows the significant fibers used in the Nonwovens industry all over the world. Fibers used in Non woven industry



WEB FORMATION

All nonwoven fabrics are based on a fibrous web. The characteristics of the web determine the physical properties of the final product. These characteristics depend largely on the web geometry, which is determined by the mode of web formation. Web geometry includes the predominant fiber direction, whether oriented or random, fiber shape (straight, hooked or curled), the extent of interfiber engagement or entanglement, crimp and z-direction compaction. Web characteristics are also influenced by the fiber diameter, fiber length, web weight, chemical and mechanical properties of the polymer.

The choice of methods for forming webs is determined by fiber length. Initially, the methods for the forming of webs from staple-length fibers were based on the textile carding process, whereas web formation from short fibers was based on papermaking technologies.

Though these technologies are still in use, newer methods have been developed. For


NEHRU ARTS AND SCIENCE COLLEGE example, webs are formed from long, virtually endless filament directly from bulk polymers; both web and fibers are produced simultaneously.

• Dry-laid Nonwovens

• Wet-laid Nonwovens

• Melt Blown Technology

• Spunbond Technology

• Nanofiber Nonwovens

DRY-LAID NONWOVENS

This technique involved the following steps:

Fiber Selection

These fibers are long enough to be handled by conventional spinning equipment.

The fibers are 1.2 to 20cm or longer, but not continuous.

Fiber Preparation

Fiber preparation consists of mechanical and pneumatic processes of handling from the bale to the point where the fiber is introduced into the web-forming machine.

• Bale opening

• Blending

• Coarse opening

• Fine opening

• Web-former feeding

Web Formation

There are two types of web formation methods are followed here

• Mechanical Web Formation (Carding or Garnetting)

• Aerodynamic Web Formation (Air-Lay)

Layering

Web formations can be made into the desired web structure by the layering of the webs from either the card or garnet. Layering can be accomplished in several ways to reach the desired weight and web structure.

1.

Longitudinal Layering :

More than once cards are involved in here. Carded webs from all the cards placed in a sequence one after the other) are laid above one another on a conveyor belt and later bonded.



Properties of the bonded webs are anisotropic in nature because of the unidirectional arrangements of fibers. This technique can only be used for making light textiles.

2.

Cross layering :

It can be done by using two different devices (cross lappers); vertical and horizontal cross lapper. Vertical lapper consists of a pendulum conveyor after the doffer roll on a card

(as shown in fig. 8). Pendulum conveyor reciprocates and lays the carded web in to folds on another conveyor belt.

3.

Perpendicular layering :

This technique has an advantage over longitudinal and cross layering because of the perpendicular and oriented fibers in the fabric. The bonded webs have high resistance to compression and show better recovery after repeated loading.

Bonding and Stabilization of Webs

Mechanical Bonding

1. Needle punching

Needle punching is a process of bonding nonwoven web structures by mechanically interlocking the fibers through the web. Barbed needles, mounted on a board, punch fibers into the web and then are withdrawn leaving the fibers entangled. The needles are spaced in a non-aligned arrangement and are designed to release the fiber as the needle board is withdrawn.

Needle punch process

The needle punch process is illustrated in fig.18.1 Needle punched nonwovens are created by mechanically orienting and interlocking the fibers of a spun bonded or carded web. This mechanical interlocking is achieved with thousands of barbed felting needles repeatedly passing into and out of the web.



The needle board: The needle board is the base unit into which the needles are inserted and held. The needle board then fits into the needle beam that holds the needle board into place. The feed roll and exit roll. These are typically driven rolls and they facilitate the web motion as it passes through the needle loom.

The bed plate and stripper plate: The web passes through two plates, a bed plate on the bottom and a stripper plate on the top. Corresponding holes are located in each plate and it is through these holes the needles pass in and out. The bed plate is the surface the fabric passes over which the web passes through the loom. The needles carry bundles of fiber through the bed plate holes shown in fig. The stripper plate does what the name implies; it strips the fibers from the needle so the material can advance through the needle loom.



The correct felting needle can make or break the needle punched product. The proper selection of gauge, barb, point type and blade shape (pinch blade, star blade, conical) can often give the needle puncher the added edge needed in this competitive industry

2. Stitch Bonding

Stitch bonding is a method of consolidating fiber webs with knitting elements with or without yarn to interlock the fibers. There are a number of different yarns that can be used.

Kevlar is used for strength in the fabric for protective vests. Lycra® is used for stretch in the fabric. Home furnishings are a big market for these fabrics. Other uses are vacuum bags, geo textiles, filtration and interlinings. In many applications stitch-bonded fabrics are taking the place of woven goods because they are faster to produce and, hence, the cost of production is considerably less.

Thermal Bonding

Thermal bonding is the process of using heat to bond or stabilize a web structure that consists of a thermoplastic fiber. All part of the fibers act as thermal binders, thus eliminating the use of latex or resin binders. Thermal bonding is the leading method used by the cover stock industry for baby diapers.

Polypropylene has been the most suitable fiber with a low melting point of approximately 165°C. It is also soft to touch. The fiber web is passed between heated calendar rollers, where the web is bonded. In most cases point bonding by the use of embossed rolls is the most desired method, adding softness and flexibility to the fabric. Use of smooth rolls bonds the entire surface of the fabric increasing the strength, but reduces drape and softness.

Chemical Bonding

Bonding a web by means of a chemical is one of the most common methods of bonding. The chemical binder is applied to the web and is cured. The most commonly used binder is latex, because it is economical, easy to apply and very effective. Several methods are used to apply the binder and include saturation bonding, spray bonding, print bonding and foam bonding. i) Saturation ii) Foam bonding iii) Spray bonding iv) Print bonding v) Powder bonding

Hydro entanglement

Hydro entanglement is a process of using fluid forces to lock the fibers together. This is achieved by fine water jets directed through the web, which is supported by a conveyor


NEHRU ARTS AND SCIENCE COLLEGE belt. Entanglement occurs when the water strikes the web and the fibers are deflected. The vigorous agitation within the web causes the fibers to become entangled.

WET-LAID NONWOVENS

Wet-laid nonwovens are nonwovens made by a modified papermaking process.

That is, the fibers to be used are suspended in water. A major objective of wet laid nonwoven manufacturing is to produce structures with textile-fabric characteristics, primarily flexibility and strength, at speeds approaching those associate with papermaking. Specialized paper machines are used to separate the water from the fibers to form a uniform sheet of material, which is then bonded and dried. In the roll good industry 5-10% of nonwovens are made by using the wet laid technology.

MELT BLOWN TECHNOLOGY

Melt blowing (MB) is a process for producing fibrous webs or articles directly from polymers or resins using high-velocity air or another appropriate force to attenuate the filaments. The MB process is one of the newer and least developed nonwoven processes.

This process is unique because it is used almost exclusively to produce micro fibers rather than fibers the size of normal textile fibers. MB micro fibers generally have diameters in the range of 2 to 4 μm, although they may be as small as 0.1 μm and as large as 10 to 15 μm.

Differences between MB nonwoven fabrics and other nonwoven fabrics, such as degree of softness, cover or opacity, and porosity can generally be traced to differences in filament size.

Process

The most commonly accepted and current definition for the MB process is: a one-step process in which high-velocity air blows a molten thermoplastic resin from an extruder die tip onto a conveyor or take-up screen to form a fine fibrous and self-bonding web.

The MB process is similar to the spun bond (SB) process which converts resins to nonwoven fabrics in a single integrated process. The schematic of the process is shown MB in figure A typical MB process consists of the following elements:

• Extruder,

• Metering pumps,

• Die assembly,

• Web formation, and

• Winding.

Extruder



The extruder is one of the important elements in all polymer processing. It consists of a heated barrel with a rotating screw. Its main function is to melt the polymer pellets or granules and feed them to the next step/element. The forward movement of the pellets in the extruder is along the hot walls of the barrel between the flights of the screw. The melting of the pellets in the extruder is due to the heat and friction of the viscous flow and the mechanical action between the screw and the walls of the barrel. There are four different heaters in the extruder, which are set in incremental order.

Metering Pump

The metering pump is a positive-displacement and constant-volume device for uniform melt delivery to the die assembly. It ensures consistent flow of clean polymer mix under process variations in viscosity, pressure, and temperature.

The metering pump also provides polymer metering and the required process pressure. The metering pump typically has two intermeshing and counterrotating toothed gears.

Die Assembly

The die assembly is the most important element of the melt blown process. It has three distinct components:

• Polymer-feed distribution,

• Die nosepiece, and

• Air manifolds.

Web Formation

As soon as the molten polymer is extruded from the die holes, high velocity hot air streams (exiting from the top and bottom sides of the die nosepiece) attenuate the polymer streams to form micro fibers. As the hot air stream containing the micro fibers progresses toward the collector screen, it draws in a large amount of surrounding air (also called


NEHRU ARTS AND SCIENCE COLLEGE secondary air) that cools and solidifies the fibers. The solidified fibers subsequently get laid randomly onto the collecting screen, forming a self-bonded nonwoven web.

Winding

The melt-blown web is usually wound onto a cardboard core and processed further according to the end-use requirement. The combination of fiber entanglement and fiber-tofiber bonding generally produce enough web cohesion so that the web can be readily used without further bonding. However, additional bonding and finishing processes may further be applied to these melt blown webs.

SPUNBOND TECHNOLOGY

Spun bond fabrics are produced by depositing extruded, spun filaments onto a collecting belt in a uniform random manner followed by bonding the fibers. The fibers are separated during the web laying process by air jets or electrostatic charges. The collecting surface is usually perforated to prevent the air stream from deflecting and carrying the fibers in an uncontrolled manner. Bonding imparts strength and integrity to the web by applying heated rolls or hot needles to partially melt the polymer and fuse the fibers together. Since molecular orientation increases the melting point, fibers that are not highly drawn can be used as thermal binding fibers. Polyethylene or random ethylene-propylene copolymers are used as low melting bonding sites. Spun bond products are employed in carpet backing, geo textiles, and disposable medical/hygiene products. Since the fabric production is combined with fiber production, the process is generally more economical than when using staple fiber to make nonwoven fabrics

Flow of operation



Process

• Spinning

• Web Formation

• Bonding



Spinning

Spun bonding combines fiber spinning with web formation by placing the bonding device in line with spinning. In some arrangements the web is bonded in a separate step which, at first glance, appears to be less efficient. However, this arrangement is more flexible if more than one type of bonding is applied to the same web.

The spinning process is similar to the production of continuous filament yarns and utilizes similar extruder conditions for a given polymer. Fibers are formed as the molten polymer exits the spinnerets and is quenched by cool air. The objective of the process is to produce a wide web and, therefore, many spinnerets are placed side by side to generate sufficient fibers across the total width. The grouping of spinnerets is often called a block or bank. In commercial production two or more blocks are used in tandem in order to increase the coverage of fibers.

Before deposition on a moving belt or screen, the output of a spinneret usually consists of a hundred or more individual filaments which must be attenuated to orient molecular chains within the fibers to increase fiber strength and decrease extensibility. This is accomplished by rapidly stretching the plastic fibers immediately after exiting the spinneret. In practice the fibers are accelerated either mechanically or pneumatically. In most processes the fibers are pneumatically accelerated in multiple filament bundles; however, other arrangements have been described where a linearly aligned row or rows of individual filaments is pneumatically accelerated.

Web Formation



The web is formed by the pneumatic deposition of the filament bundles onto the moving belt.

A pneumatic gun uses high-pressure air to move the filaments through a constricted area of lower pressure, but higher velocity as in a venture tube. In order for the web to achieve maximum uniformity and cover, individual filaments must be separated before reaching the belt. This is accomplished by inducing an electrostatic charge onto the bundle while under tension and before deposition. The charge may be induced triboelectrically or by applying a high voltage charge.

Bonding

Many methods can be used to bond the fibers in the spun web. Although most procedures were developed for nonwoven staple fibers, they have been successfully adapted for continuous filaments. These include mechanical needling, thermal bonding, and chemical bonding. The last two may bond large regions (area bonding) or small regions (point bonding) of the web by fusion or adhesion of fibers. Point bonding results in the fusion of fibers at points, with fibers between the point bonds remaining relatively free.

Other methods used with staple fiber webs, but not routinely with continuous filament webs include stitch bonding, ultrasonic fusing, and hydraulic entanglement. The last method has the potential to produce very different continuous filament structures, but is more complex and expensive. The choice of a particular bonding technique is dictated mainly by the ultimate fabric applications; occasionally a combination of two or more techniques is employed to achieve bonding.

LAMINATING

Laminating is the permanent jointing of two or more prefabricated fabrics.

Unless one or other of the fabrics develops adhesive properties in certain conditions, an additional medium is necessary to secure bonding.

• Wet laminating: Adhesives used in the wet process are dissolved or dispersed in a suitable solvent. The simplest form of wet laminating consists of applying the adhesive to one of the lengths of material that is to be joined, and to put the second length on it with the required amount of pressure. Then drying, hardening or condensing the material that has been joined together is carried out. The solvents can be macromolecular natural or synthetic substances and water.

• Dry laminating: All Kinds of thermoplastics are used for dry laminating.

These include powders, plastisols, or melt adhesives, and are applied to the substrates that are to be joined together using suitable machinery. Dry laminated non-woven fabrics have a soft feel

.

APPLICATIONS

Non-woven materials are nowadays mainly produced from man-made fibers. Two synthetic polymers dominate the market: polypropylene (PP) and polyesters mainly PET). Nonwovens


NEHRU ARTS AND SCIENCE COLLEGE are often application-designated as either durable or disposable. For example, nonwovens used as house wraps to prevent water infiltration are durable nonwovens. Nonwovens used as facings on baby diapers are disposable or single-use nonwovens.

Non-woven materials are used in numerous applications, including:

Hygiene

• Baby diapers

• Feminine hygiene

• Adult incontinence products

• Wipes

• Bandages and wound dressings

• Medical

• Isolation gowns

• Surgical gowns

• Surgical drapes and covers

• Surgical scrub suits

• Caps

Technical

• Roll roofing and shingle reinforcement

• Insulation backing

• Battery electrode separators

• Vinyl flooring reinforcement

• Plastic surface reinforcement (veils)

• Wall coverings

• Honeycomb structural components

• Ceiling tile facings

• Circuit board reinforcement

• Electrical insulation

• Filters

• Gasoline, oil and air - including HEPA filtration

• Water, coffee, tea bags

Geo textiles

• Soil stabilizers and roadway underlayment

• Agriculture mulch

• Pond and canal water barriers

• Sand infiltration barrier for drainage tile

Other

• Carpet backing, primary and secondary



• Composites

• Marine sail laminates

• Table cover laminates

• Backing/stabilizer for machine embroidery

• Insulation (fiberglass batting)

• Pillows, cushions, and upholstery padding

• Batting in quilts or comforters

• Consumer and medical face masks

• Tarps, tenting and transportation (lumber, steel) wrapping

• Disposable clothing (foot coverings, coveralls)

FELTING

• Felt - Felt is a non-woven cloth that is produced by matting, condensing and pressing fibers. The fibers form the structure of the fabric.

• Felting - The process of making felt is called felting.

Felt is a dense, non-woven fabric and without any warp or weft. Instead, felted fabric is made from matted and compressed fibers or fur with no apparent system of threads. Felt is produced as these fibers and/or fur is pressed together using heat, moisture, and pressure. Felt is generally composed of wool that is mixed with a synthetic in order to create sturdy, resilient felt for craft or industrial use. However, some felt is made wholly from synthetic fibers.

Raw Materials

Felt is produced from wool, which grips and mats easily, and a synthetic fiber that gives the felt some resilience and longevity. Typical fiber combinations for felt include wool and polyester or wool and nylon. Synthetics cannot be turned into felt by themselves but can be felted if they combine with wool.

Other raw materials used in the production of wool include steam, utilized during the stage in which the material is reduced in width and length and made thicker. Also, a weak sulfuric acid mixture is used in the thickening process. Soda ash (sodium chloride) is utilized to neutralize the sulfuric acid.

The Manufacturing

Process

• Since some felts use more than one type of fiber, the fibers must be mixed and blended together before any processing begins. To do this, the raw fibers are put into an opener with a big cylinder studded with steel nails that combine the fibers into a mass.



• Next, these blended fibers must be carded. Carding machines are huge cylinders that mat the fibers into a web. Hopper-feeders allow a specific weight of fiber to pass into the cylinder in order to create a standardized web. The fibers in the web are pulled by the wires, or carded, so that they are parallel to one another.

• Generally, at least two carding machines are used in the manufacturing process, each refining the web as it creates a new one. A transporter moves one web from the first carding machine to a second. The web is then fed into the second machine. This second carder generates a new web that is thicker and fully carded.

• At the end of the second carding, a comb removes the carded web from the machine and rolls it up. There are two ways to remove the web from the machine: a cross-lapper may be used in which the web is perpendicularly rolled up, or across the direction of the fibers; or a vlamir may be utilized, in which the web is rolled parallel to the direction of the fibers.

• Next, several different webs are combined to create one thick web. Four rolls of web are rolled up but are layered so that their fibers alternate in direction based on the way the webs were rolled, either cross-lapped or rolled using a vlamir. These four rolls are considered a standard single roll, sometimes referred to as a batt. This batt is considered a standard roll of material. Batts are layered in order to create different thicknesses of felt.

• The batts of felted material must be hardened or matted together in order to create thick, densely-felted material. The first step in this process is subjecting the batts to heat and moisture. In order to do so, the batts are passed through a steam table.

• Now, the separate batts must be matted together and shrunk in length and width in order to create a dense felt. These batts must be subjected to heat, moisture, and pressure in order to be matted densely. First, the wetted batts are fed into a plate-hardener that shrinks the width of the fabric. The plate-hardener consists of a large, square flat bed with a large plate that drops down over the batts of wet, hot batts, exerting pressure on the material and compressing it. At the same time, the plate-hardener oscillatesm from edge to edge, further matting the fiber to a specific width.

• Next, the batts are fed into a fuller or fulling machine, which shrinks the length to a specific measurement. As it shrinks, the felt becomes more dense. The batts are fed through a set of upper and lower steel rollers that are covered with hard rubber or plastic and are molded with treads much like a car tire, enabling them to move across the batts. The felt is continuously wetted with a hot water and sulfuric-acid solution. The upper rollers remain stationary as the lower rollers are moved upwards to put pressure on the fabric and push it against the upper rollers. All of the rollers, both upper and lower, move together forward and backward. The pressure, the acid, the hot water, and the movement cause the batts to shrink in length, making the felt even more dense. For example, a single piece of felt that is 38 yd (34.7 m) long may come out of the fuller at only 30 yd (27.4 m) in length.

• The wet felt has sulfuric acid residue and must be neutralized. To do so, the felt is run through neutralizing tanks filled with a soda ash and warm water solution. This process is carefully timed so that specific yard lengths and widths are in for an exact amount of time.



• The neutralized felt is then run through a refulling machine in which heavy rollers run over the surface of the fabric one last time to smooth out any irregularities.

• If felts are to be dyed, the wet pieces are taken to a dye vat. Some industrialgrades are not dyed but go directly to drying.

BRAID

To interweave three or more strands, strips, or lengths of in a diagonally overlapping pattern. A braid is an interweaving or twinning three or more separate strands in a diagonally overlapping pattern. The strands may be of one or more materials. Braids are commonly involved in hairstyling and rope making. Simple braids with more than three strands can be flat or tubular and generally contain an odd number of strands. Complex braids have been used to create hanging fiber artworks. A braid is similar to a plait, which covers any type of knot forming a repeated pattern.

In fiber optics and electrical and electronic cables, braid is a tubular sheath made of braided strands of metal placed around a central cable for mechanical protection or grounding purposes. Such braids are also used after flattening for bonding large components together. The numerous smaller wires comprising the braid are much more resistant to cracking under repeated motion and vibration than is a cable of larger wires.



TATTING

Tatting is a technique for handcrafting a particularly durable lace constructed by a series of knots and loops. Tatting can be used to make lace edging as well as doilies, collars, and other decorative pieces. The lace is formed by a pattern of rings and chains formed from a series of lark's head (or half-hitch) knots, called double stitches (ds), over a core thread.

Gaps can be left between the stitches to form picots, which are used for practical construction as well as decorative effect.

Technique

1 Shuttle tatting

2 Needle tatting

3 Cro-tatting

1.

Shuttle tatting

Tatting with a shuttle (Fig 19.2) is the earliest method of creating tatted lace. A tatting shuttle facilitates tatting by holding a length of wound thread and guiding it through loops to make the requisite knots.

In fiber optics and electrical and electronic cables, braid is a tubular sheath made of braided strands of metal placed around a central cable for mechanical protection o r grounding purposes. Such braids are also used after flattening for bonding large components together. The numerous smaller wires comprising the braid are much more resistant to cracking under repeated motion and vibration than is a cable of larger wires.

It is normally a metal or plastic pointed oval shape less than 3 inches long, but shuttles come in a variety of shapes and materials. Shuttles often have a point or hook on one end to aid in the construction of the lace. Antique shuttles and unique shuttles have become highly sought after by collectors

2. Needle tatting



A tatting needle is a long, blunt needle that does not change thickness at the eye of the needle. The needle used must match the thickness of the thread chosen for the project. Rather than winding the shuttle, the needle is threaded with a length of thread.

2.

Cro-tatting

Cro-tatting combines needle tatting with crochet. The cro-tatting tool is a tatting needle with a crochet hook at the end. One can also cro-tat with a bullion crochet hook or a very straight crochet hook. In the nineteenth century, "crochet tatting" patterns were published which simply called for a crochet hook. One of the earliest patterns is for a crocheted afghan with tatted rings forming a raised design.

CROCHET

• Crochet - The word crochet describes the process of creating fabric from a length of cord, yarn, or thread with a hooked tool.

• Crochet hook - A crochet hook is a type of needle, usually with a hook at one end, used to draw thread through knotted loops.

Crocheting differs largely from knitting in that there is only one loop, not the multitude as knitting has. Also, instead of knitting needles, a crochet hook is used. Other than that it is vaguely similar, and is often mistaken for knitting. Lace is commonly crocheted, as well as a large variety of other items.

Process

Crocheted fabric is begun by placing a slip-knot loop on the hook, pulling another loop through the first loop, and repeating this process to create a chain of a suitable length.

The chain is either turned and worked in rows, or joined to the beginning of the row with a slip stitch and worked in rounds. Rounds can also be created by working many stitches into a single loop. Stitches are made by pulling one or more loops through each loop of the chain.

At any one time at the end of a stitch, there is only one loop left on the hook. Tunisian crochet, however, draws all of the loops for an entire row onto a long hook before working them off one at a time.



CALICO

Calico is a type of fabric made from unbleached, and often not fully processed, cotton, also referred to a type of Printing.

NETTING

Netting is an open-mesh form of fabric construction that is held together by knots or fused thermoplastic yarns at each point where the yarns cross one another. There are several types of mesh; they are square, hexagonal, and octagonal. The range of mesh sizes is from coarse and opens to fine and shear.

Netting may be made of any kind of fiber and may be given a soft or stiff sizing.

Net fabrics are relatively fragile and require care in handling and cleaning. Torn net fabrics cannot be satisfactorily mended because the repair would be apparent. If the sizing is water soluble, the fabric should be dry-cleaned. There is a variety of netting; some are produced under specific trademarks.

Among the best known standard fabrics are noted here.

• Bobbinet is a thin to medium weight hexagonal netting. A typical use is for bridal ceils

.

• Malines is a very thin, diaphanous diamond-shaped net named after the city of Belgium, its origin.

• Tulle is a fine, stiff netting of hexagonal mesh. It is generally used for trimming or over draping of dress goods.


1.

What are non-wovens? Explain felting, fusing, bonding ,lamination ,netting, braiding and calico, tatting and crotcheting.

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