Textile Fiber Definition [An Introduction] Fiber is the first elementary raw material of textile manufacturing. To understand the whole textile manufacturing process, it is essential to have a good knowledge about textile fiber definition. There are two types of textile fibers: it is either natural or man-made, in form of staple or filaments. The types of textile fiber determine their uses. Natural fibers are those fibers that are directly produces at nature, usually at plants, animals or minerals. Man-made synthetic fibers or artificial fibers which are usually manufactured from solutions of natural polymer (cellulose, milk protein) or derivatives of natural polymer. Textile fibers should exhibit some specific properties which is discussed in this content below. Textile Fiber Definition Textile fiber is a class of materials that are natural or manufactured can takes only tensile force not compression and spun into yarn by twisted to-gather or also converting into fabric (non-woven) direct from fiber. If two fibers are twisted to-gather is stronger than both individual without increasing its tenacity. Fiber is continuous filament or is in discrete piece (staple). It is the smallest visible substance which is extremely thin in relation to its width at least 500 times longer than its lateral dimension. Types of textile fiber There are two types of fibers: 1. Natural fiber 2. Man-made fiber Natural fiber Natural fibers are of three types: 1. Vegetable, Example: Cotton, Kapok, Coir (They are from Seed); Jute, Flax, Ramie (Baste); Abaca, Sisal, Henequn (They are from leaf) 2. Animal, Example: Wool, Silk, Hair 3. Mineral, Example: Asbestos Man-made fiber These fibers are basically two types: 1. Regenerated, Example: Viscose, Lyocell, Modal, Cupro, Acetate, Tri-acetate, Alginate, Rubber, Casein, Protein 2. Synthetic, Example: Polyester, Nylon, Polyolefin, Polyvinyl acrylic, Elastane 3. Others: Glass, Carbon, Aramid, Metallic Properties of Textile Fibers There are several properties necessary for a polymeric material to make an adequate and appropriate fiber to certain end uses. A fiber has to the following physical and chemical properties to meet some specific requirements and these are: Fiber length Length to width ratio (Slenderness ratio) Tensile properties (Strength/Elongation) Elasticity Flexibility Elastic recovery from strain Cohesiveness Wet-ability Dye-ability Density Comfort to human skin Resiliency Toughness Work of rupture Fiber friction Uniformity Crimp Fineness (MIC) Color/Luster Maturity ratio High abrasion resistance Chemical resistance Textile Fiber Structure Textile fibers are a class of solid organic polymers. This distinguishes them from other polymers by their physical properties and geometric dimensions. But a few exception exists. This tem can’t be applicable for a few specialty fibers like glass, asbestos etc. as they are based on inorganic substances. Fiber can be easily identifiable. It is extremely long with respect to width, flexible and has high anisotropic physical properties. But the only thing that differs fiber from the other polymers is their molecular structure. This molecular structures decide the physical and chemical properties of fibers. Levels of molecular structure For the ease of perception, let’s consider three levels of molecular structure. Each level relates to certain aspects of fiber behavior and properties. The Organo-chemical Structure >It defines the structure of repeating units in the base polymer. >Also, it describes the nature of polymeric link. >It is directly related to chemical properties, dyeability, moisture absorption, swelling characteristics and indirectly all the physical properties. The Macro-molecular structure >It entitles the family of polymer molecules. >Chain length, chain length distribution, chain stiffness, molecular size and molecular shape, all these parameters are characterized by this structure. The Super-molecular Structure >Describes the arrangement of the polymer chains. >Polymer orientation, crystallinity and fibrillar structure all these may be described by this structure. In general, the textile fibers useful for textile applications are semi-crystalline and irreversibly oriented polymer. The fibers have highly oriented molecular chains in some region where they are closely packed and near arranged. This regions are named as crystalline region. The physical properties of fibers are strongly influenced by degree of orientation or the degree of crystallinity. The textile fiber has some regions where the molecular chains are not well oriented, tending to a random coil configuration. These regions are referred to as amorphous region. Various identifiable aggregates of polymer chains are found in case of natural fibers. These are often referred to as micelles, fibrils, micro-fibrils etc. Fiber Polymer System Molecular segment is the basic unit of the textile fiber. This is called monomer. It is repeated to form a long chain or macro-molecule. This is called polymer. From two or more different monomers, formation of polymer can also be achieved. This is called co-polymer. To make up a co-polymer, there is no definite regularity in the order of monomers. Some fibers contain additional monomers. They are not a part of the polymer chain rather they are incorporated to improve certain properties like dye affinity. These are grafted on the polymer chain as side group. Cotton The word cotton comes from Arabic word “Katan”. It is called the king of fibers just only because of the characteristics of cotton. Cotton is the backbone of world’s textile market and it is also one of the most important and widely produced agricultural and industrial crops in the world. Cotton is grown is about 80 different countries. The most important producers are China, USA, India, Pakistan, Uzbekistan, Turkey, Australia, Brazil, Argentina, and Syria. In this article we will discuss about the characteristics of cotton, types, physical and chemical properties of cotton. Characteristics of Cotton Comfortable Light weight Non-elastic Good draping quality Feels soft Super absorbent Color retention capacity is good Dry cleanable Machine wash is possible Great strength Good cooling properties Dries fast Extremely shiny Moisture absorption is very good Very durable Wet fibers are more resistant Morphological structure Cotton contains 95% cellulose. High grade, soft material with super absorbent quality- all these qualities are extremely suitable for cotton. Cotton is of different colors based on its origin. Cotton fiber length varies between 10 to 65 mm. American cotton has white color whereas Egyptian and Chinese cotton has yellowish and red-yellowish color respectively. Under microscope the fiber appears to beRibbon like Kidney-shaped cross-section Natural convulation of longitudinal view Having two ends Twisted in a spiral, tightly and regularly wrapped in high end fiber With sanforization and mercerization process, the properties of cotton can be improved. Morphological structure of cotton Structural view of cotton Polymeric structure of cotton Cotton is a cellulosic fiber.80-90% cellulose is in cotton but oil, wax, protein, pectin and some coloring content are also present. The polymer chain of cotton cellulose is linear. It is a polymeric sugar of polysaccharide made up of 4000-9000 repeating cellobiose unit, which consists of two glucose units connected to each other by 8-ether linkages. The number of repeating unit of a polymer chain is called Degree of Polymerization (DP). If 5000 repeating unit stay in a polymer chain then its Degree of Polymerization is 5000. Macro structure of cotton Grading & Classification of Cotton The word Grading means the rating of cotton according to quality parameter of cotton. Cotton is classified by grading and it is done according to length, fineness, strength, color, lusture and impurities. This division is done by different way according to the production land. Different grading systems Properties of different cotton fibers with spinning limit General Physical & Chemical Properties of Cotton fiber Fiber Length: Varies from 10-65 mm Fiber Strength: Strength is varied 24-32 gm/tex Fineness: The value varies 3-6 Maturity ratio: varies from 0.7-0.9 Color: Light yellow or brown Moisture Content: 8.5% Gravity: 1.48 – 1.51 g/cm3 Effects of Acids: Cotton fibers are weakened by cold weak dilute acids and degraded by strong acids. Effects of Alkali: Unaffected or undamaged by alkaline solution Types of Cotton yarns 100% Cotton These yarn has 100% cotton fibers. Garments containing 100% cotton yarn has ability to absorb sweat immediately. It has cooling properties. So, this is used in hot weather extensively. But blends of cotton is cheap than this. For maintaining high quality, 100% cotton is used to make garments or apparels. CVC CVC stands for chief value cotton. A blended yarn having more percentage of cotton as compared to that of polyester is called CVC yarn. For example: Cotton: Polyester 70: 30. Pricing of CVC is still too high. PC Yarn produced by blending of cotton and polyester fibers. The maximum part of these yarns are polyester. The yarn contains more than 50% of polyester. The rest part is cotton. TC TC stands for Terelyne – Cotton. This is also made by blending of cotton and terelyne fibers. But in this case, the higher amount used is polyester fibers and the rest portion is cotton fibers. TC yarn is used for making apparels most of the time. This provides the soft and cool feel of cotton to the user. Identification of cotton fiber There are different tests which could be used for the identification of the cotton fiber. It is suggested to combine at least two or more different methods to reach an acceptable and reliable conclusion in practice. Feeling test: Unresponsive, smooth and a soft hand to human skin, feels good against skin. Burning test: The reaction of fibers to heat from an open flame is a useful guide in identification of fibers. Non melt, burn. Smell like paper burning. The smell of cotton burning is like of paper burning because paper is also a cellulosic material. Some technical tests are required for detailed identification Microscopic identification Chemical test Coloring with dyestuffs Solubility test: Cotton is easily dissolved by H2SO4 Staining End use Apparel Home textile to Industrial textiles Different Types of Cotton Cotton is, by far, the most important textile fiber. There are different types of cotton fibers according to their staple length and plant varieties. With the plant varieties, their quality also varies. To produce top quality product, we need optimum quality cotton fibers. Cotton consists of cellulose, a polymer of glucose. Cellulose is the basic building material of all types of vegetation and many different plants are sources of cellulose fibers. How we get cotton? Cotton comes from the seed pod of plants in the Gossypium family cultivated in a number of subtropical climates. The fibers grow out of the seeds in the closed pod. In the initial phase, they form long, thin-walled cells filled with protoplasm. Later, as the growth in length ends, the cell walls increase in thickness as rings of cellulose are deposited on the inner surface of the cell wall. When the pod or boll bursts, the cotton fibers, whose function is to aid seed transport in the wind, dry out. Once the remaining protoplasm has evaporated, the cotton bolls are harvested mechanically and the fibers removed from the seeds by a process called ginning. This must be carefully controlled to avoid over-cutting of the fibers. Cotton ‘linters’, the short lint hairs not removed from the seeds by ginning, are also an important source of pure cellulose. Pressing the residual seeds gives cotton seed oil. Types of cotton In different parts of the world, many cotton fiber is grown with wide range growing conditions. As a result, there are many grades of cotton fibers around the world. They are of various quality that vary widely with their characteristics and properties. It is a quite difficult job to assess the quality of cotton. It requires great skill and experience. Quality of cotton is directly related with staple length and its characteristics which is generally quoted to refer any cotton. Staple length is an assessment of fiber with respect to its technically most important length. In case of cotton, staple length corresponds very closely with the most frequent length of the fibers when measured in a straightened condition. Commercial Types of Cotton Commercial cotton may be classified broadly into three categories. Here they are: Staple length 1-1 ½ inch (26-65 mm): Includes the fine, lustrous fibers which forms the top quality cotton. The fibers are generally of 10 -15 microns diameter and are of 1.1-1.8 dtex (0.99-1.62 den). Sea Island, Egyptian, American pima are in this category. These are high category cotton. These cottons are difficult to grow. Their supply are comparatively low. Staple length ½ – 1 5/16 inch (12-33mm): This includes medium strength, medium luster cotton. This form the bulk of the world crop. These fibers are generally of 12-17 micron diameter and are of 1.4-2.2 dtex (1.26-1.98 den) American upland and some Peruvian types fall into this category. Staple length 3/8 – 1 inch (9-26mm): This includes coarse and low grade fibers. They are low in strength and have little or no luster. They are generally of 13-22 microns diameter. They are of 1.5-2.9 dtex (1.26-1.98 den) Many of Asiatic, Indian and some Peruvian cottons fall in this category. Types of Cotton depending on cotton plant varaites According to plant varieties, there are 4 types of Cotton. Gossypium hirsutum (Upland cotton) Most widely this type of cotton is produced. 90% of the world’s cotton production is from this category. Cotton from Central America and the Caribbean Sea Island accounts for this category. These are exported to every location throughout the world. They are characterized by short-staple fiber that grows in any climate. For making a quality fabric that all can afford, Upland is perfect. Especially in the US, this type of cotton mostly plants. Or you can say, 95% of fibers grow in American soil. Gossypium Hirsutum (Acala cotton) San Joaquin Valley Acala, the cotton type only produced by California. Among all of the upland cotton, this type is the highest quality cotton. This type of cotton gets benefits from the climate of San Joaquin Valley. Acala cotton gets an extended growing period that increases yield. As a result, we get a finer product. This type of cotton is a bit costlier than American Upland cotton. This is due to its growing requirements. Gossypium barbadense (Pima Cotton) This type of cotton accounts for 8% of the world’s cotton production. These are more expensive than the previous one. This type of cotton consists of extra-long staple fiber. Textiles become softer and lustrous with this type of cotton. South American cotton is from this category, they are exported throughout the world. Pima kind of cotton is from this category. Producers from China and India produce this cotton. So, what’s the benefit of using this extra-long staple fiber? It makes the fabric strong that makes it resistant to fraying, fading, wrinkling, and pilling. Gossypium herbaceum (Egyptian cotton) This type of cotton grows in longer bushes that can be considered as tree. This accounts for 2% of the world’s condition. As like as Pima cotton, this type of Egyptian cotton is from extra-long staple fiber. This quality makes it also soft, supple, and vibrant in performance. So what is the difference between Egyptian cotton and Pima cotton? The main difference is in the cultivation process of cotton. Egyptian cotton is grown at hot and dry climate beside Neil River in Egypt. This type of cotton is exceptionally quality full. Gossypium arboretum This type of cotton is from Arabia and Africa. This accounts for not more than 2% of the world’s cotton cultivation. To Wrap Up! Cotton and Viscose contain pure cellulose among all fibers. Other natural fibers containing cellulose, also contain some other constitutional materials. Although cotton and viscose are almost pure cellulose, they have quite different physical properties because of their distinctive morphologies and molecular arrangements.