PRODUCTION OF WOOD ADHESIVE FROM LOCALLY SOURCED MATERIAL
(PRODUCTION OF ECO-FRIENDLY ADHESIVE FROM CASSAVA (Manihot Esculenta)
STARCH)
May 2018
Introduction
History made known that Egyptians used starch and cassava during
Pharaoh’s era, the claims was attested to the discoveries of glued cedrewood chest and other glued objects found in the thumb of Tutankhamun
1356 BC (Ebnesajjad, 2010).
adhesives are vital ingredients for the manufacturing of wood-based
composite panels, including plywood, oriented strand board, mediumdensity fiberboard, and laminated veneer lumber.1,2 Urea–formaldehyde
(UF) adhesive, phenol–formaldehyde (PF) adhesive, and melamine–
formaldehyde (MF) adhesive are the commonly used conventional
thermosetting wood adhesives.
Man’s growing desire to hold two or more substance together by surface
attachment so that they can be used as a single piece coupled with the
technological advancement has given birth to a broad range of adhesive
production to serve this purpose.
The first commercial glue plant was founded in Holland in 1690, that
casein glues appear to have been manufactured in Germany and
Switzerland in the early nineteenth century, and that the first U.S Patent
Number 183,024 on a casein glue was issued in 1876.
He mentioned that starch adhesive were used on postage stamps when
they were first issued in 1840, and that of the first U.S Patent Number
61991 on a dextrin adhesive was issued in 1867 ( John, 1947).
Before the advent of synthetic resin adhesives, semi synthetic cellulosic
materials were developed but when they were first dissolved in solvents
and used as an adhesive is not clear from literature.
Historically, the first thermoplastic synthetic adhesive (only partly
synthetic) was the cellulose ester, cellulose nitrate, often called
nitrocellulose, and it is still one of the most important.
Later, other esters such as the acetate were developed as well as certain
mixed esters (John, 1947).
The solvent-free process use is largely growing nowadays, due to the
economic and environmental benefits. Currently, the company aims to
change the production process of some products from the solvent-based
method to a solvent-free one. However a simple one-to-one transfer of
the adhesive formulation proved to be problematic.
The country has more than 2,700 hectares of rubber tree plantation; from
this plantation 80,000litre of latex has harvested per day with additional
expansion plan in Illubabor, mettu area. In Ethiopia the adhesive and
tape industry is dependent on imported product.
The aim of this study is to synthesize wood adhesive from locally
sourced raw materials with the views of using it in furniture work and to
achieve self and economic reliance by depleting our dependence on
imported varieties of foreign adhesives based on the growing need for
adhesive in our industries.
Materials and Methods
Materials
1. Calcium Carbonate
2.
3.
4.
5.
6.
7.
8.
9.
Surfactant
Antifoam
Water
Polyvinyl acetate (P.V.A)
Nitro sol Cellulose
Formaldehyde
Starch
Sodium hydroxide
Methods
Extraction of Starch from Cassava: the cassava tubers will buy from
southern part of Ethiopia. Before use, the cassava tubers will peel and
washed. The peeled cassava will be soaked in water for two hours (120
minutes) for hydration.
The cassava tubers will be grinded with grinding machine, in order to
increase the surface area and reduce the starch granules. This breaks the
plant cell and thus releases the starch. After grinding, fine cassava will
be obtained which will soaked in water and left for about four hours.
Just to allow the cassava fine particles to settle. The fine cassava
particles will screen with 100 micrometer baft. More water will be added
As the cassava slurry will rubbed on top of the sieve to achieve proper
separation of the chaff or fiber from the main starch. As separation
continues, the starch and water escapes through small pores while chaff
and cell debris are retained on the surface of the screen. The starch and
water will allowed to stay overnight in order for it to settle down. Then
the water will slowly decanted and the surface of the starch will washed
with water to remove dirt and non- starch which has settled with the
starch. The starch will spray on a clean tray and thoroughly sun-dried, so
that it could be stored and preserved. 20 tubers of cassava which
weighed 8.0kg, after processing yield 350g (0.35kg) of cassava starch.
Production of Wood Adhesive from Cassava Starch: 600g of cassava
flour, two formulations with different wood adhesive properties based
on different additives combination will make.
Material Formulation
72.5ml of water will introduced into a reaction pot, but the total quantity
water required for the production will be 145ml, 1g surfactant will be
added to the reaction pot already containing water, to ensure even
mixing of the materials. To avoid foaming 1g of Anti-foamier will be
added to the reaction pot contains water and surfactant. 50g of starch
will be dissolved in cold water, mixing of the starch and alkali solution
will be done to enable the starch gel. In the course of gelatinization the
Content of the amorphous areas of the granules is dispersed first,
followed by the swelling of the more tightly packed crystal lone portions
and amylose leaching.
The starch is then transferred to the reaction pot, after which it will left
for a while to enable proper mixing of starch and1g of calcium carbonate
when this will done. 115g and 100g of polyvinyl Acetic will be
introduced. A little quantity of the thickener will dissolved in a little
water from the remaining 72.5ml of water and then will added to the
reaction pot. Bit by bit the 1gNitrosol cellulose was dissolved, the
mixture will well stirred before pouring into the pot. Not more than 1g
will used in dissolving the thickener. 1g of formaldehyde will added for
Preservation that is to free the glue from germs that might contaminate
it.
Objectives of the project
o To produce wood adhesive from locally sourced materials
Specific objectives
o To characterize the quality and composition of adhesive from
cassava starch
o To attract new investment in the sector
o To reduce the harmful gas emissions of these formaldehyde-based
adhesives
o To study the potential of local cassava raw material for the
manufacturing of wood adhesive.
Significance of the project
The principal interest in the production of wood adhesive from cassava
plant is to provide an excellent quality product with least cost and the
availability of raw material locally in southern part of the country for
further cultivation of cassava plant.
It play a significant role by minimizing foreign currency dependency
and creating an integrated back and forward linkage between adhesive
manufacturer and furniture industries. It will attract new investment for
the sector; job, technology and knowledge transfer opportunity also a
considerable importance for local citizens.
The study will become a reference for further investigation in
developing an alternative product and innovation for professionals to
substitute imported raw materials by local input.
Scope of the Study
The scope of this research work covers; a collection of cassava tubers from
southern part of Ethiopia, characterization of their contents, preparation of
adhesive from cassava starch, physico-mechanical property testing, determining
the operating parameters. In this study the suitability of raw material (cassava
starch) according to the standard will be studied for the preparation of adhesive.
Significance of the Study
The significance of this thesis is mainly focus on transforming cassava starch into
the valuable products a so called cassava starch adhesive. The optimum process
conditions for producing modified starch adhesive as environmental friendly,
renewable and biodegradable will be determined.
MATERIAL AND METHODS
The study area and sampling methods
The study area is Benji Maji zone, gura farda woreda bebeka area which
is found in SNNPR in the South-western Ethiopian highlands at 651”30”
- 7 11”00” North latitude 609km from Addis Ababa with altitude 8001000masl the average annual rainfall 1862.9mm and 154 evenly
distributed throughout the year rain days (Ethiopia investment agency,
2012).
For this experimental analysis, the Latex will be tapped from natural
rubber tree and properly stored for laboratory scale experiments. A
small-scale Adhesive tape production pilot plant will be designed and
the results from each sample will be analyzed.
Expected outcome
 Chemical composition of cassava will be investigated
 The adhesion property of cassava starch will be investigate
 The effect of temperature, pH, substrate concentration, catalyst and
structure, on adhesion property will be optimized
 The moisture content of the cassava starch and its effect on product quality
will be investigated
 Optimum product of biodegradable adhesive will be produced from locally
available cassava plant.
Statement of the Problem
All most all wood work manufacturers (furniture industries) in Ethiopian
uses expensive adhesives i.e. phenol and urea formaldehyde. This synthetic
adhesives formaldehyde emission is very high which is harmful to human
health (carcinogen) and environment.
Abstract
Adhesive is bonding material most widely used in manufacturing sectors like shoe,
wood, textile, papers, and others. Most of these manufacturing sectors rely on
using petroleum-based adhesives such as urea formaldehyde, polyvinyl acetate,
and phenol formaldehyde resins. As these adhesives are produced from nonrenewable resources and they are also carcinogenic to human beings due to
formaldehyde emission, it is necessary to prepare adhesives from bio-based
sources. In this research bio-based adhesive will be produced using cassava starch
as a renewable feedstock. The process of bio-adhesive production Includes
extraction of latex from branches of Euphorbia tirucalli using water as a solvent
and mixing the extracted latex with silica to formulate the adhesive. 21.6
percentage yield of liquid latex was obtained from the extraction section.
Key words: bio-adhesive, viscosity, lap shear strength, and Euphorbia tirucalli
Problem Statement
In our country Ethiopia due to the growth of different manufacturing sectors
specifically textile, shoe, woodworks, packaging industries and bookbinding, the
demand for adhesives has increased significantly over the years. The country`s
requirement of adhesive is met through import which leads to additional foreign
currency demand. Furthermore, most of the current produced adhesives are
basically made from petroleum derived chemicals which are non-renewable and
environmentally
unfriend.
Adhesives
like
urea
formaldehyde,
phenol
formaldehyde, and poly vinyl acetate are the most commonly used petroleum
based products in many manufacturing sectors. However, the increasing cost of
petrochemical-based products ,depletion of petroleum and growing perception of
environmental protection have encouraged the development of bio-based adhesives
from cheap and renewable resources. In addition, these types of adhesives are
highly volatile and are also classified as gaseous contaminant as well as
carcinogenic substance (Thuraisingam et al., 2016). As a solution to the problems,
it is inevitable to replace petroleum based adhesives by bio-based adhesives.
Beside the mentioned problems, the raw materials required to produce synthetic
adhesives are also not available in Ethiopia. Therefore, it is necessary to consider
how to use locally available natural resources. In this study starch from cassava
plant is opted as a potential source of raw material to prepare bio-adhesive.
Significance of the Study
This proposal work will be aimed at import substitution of petroleum based
adhesives which Ethiopia is importing by way of renewable and locally available
adhesive. This study will initiate the country to reduce importing petroleum-based
adhesives via replacing them with renewable-based adhesive which has higher
attribute than the current one which will in turn decrease value of importing and
transportation. In this way the country will become self-sufficient. In addition it
brings the county to green economy system.
In summary, once the research is done successfully and implemented, it is
expected to have the following significances.
 Reduce cost of production for the manufacturing sectors like furniture, textile
and others as they decrease cost for buying the adhesive from aboard.
 Farmers who cultivate the tree will be benefited financially.
 Create employment for the local people
Therefore, as stated above this proposal work will possess significance on the
society, environment and country.
Literature Review
Definition of Adhesive and Adhesion
The dictionary defines an adhesive/glue as a substance capable of holding materials (adherent)
together by surface attachment. Adhesion is the state in which two surfaces are held together by
interfacial forces, which may be valence forces, interlocking action, or both while an adherent is
a substrate held to another substrate by an adhesive(Mwambusi, 2016).
Historical Background of Adhesive Production
The earliest use of adhesives was discovered in central Italy when two stone flakes partially
covered with birch-bark tar and a third uncovered stone from the Middle Pleistocene era(200,000
years ago) were found. This is thought to be the oldest discovered human use of tarhafted stones
(Peter et al., 2006).The birch-bark-tar adhesive is a simple, one-component adhesive. Although
sticky enough, plant-based adhesives are brittle and vulnerable to environmental conditions. The
first use of compound adhesives was discovered in Sibudu, South Africa.Here,70,000-year-old
stone segments that were once inserted in axe hafts were discoveredcovered with an adhesive
composed of plant gum and red ochre (natural iron oxide) as adding ochre to plant gum produces
a stronger product and protects the gum from disintegrating under wet conditions(Wadley et al.,
2009). The ability to produce stronger adhesives allowed middle stone age humans to attach
stone segments to sticks in greater variations, which led to the development of new tools
(Wadley, 2014).
The first references to adhesives in literature first appeared in approximately 2000 BC. Further
historical records of adhesive use are found from the period spanning 1500–1000 BC. Artifacts
from this period include paintings depicting wood gluing operations and a casket made of wood
and glue in King Tutankhamun's tomb(Ebnesajjad, 2010). Other ancient Egyptian artifacts
employ animal glue for bonding or lamination. Such lamination of wood for bows and furniture
is thought to have extended their life and was accomplished using casein (milk protein)-based
glues. The ancient Egyptians also developed starch-based pastes for the bonding of papyrus to
clothing and a plaster of Paris-like material made of calcined gypsum(Mittal, 2003).From AD 1
to 500 the Greeks and Romans made great contributions to the development of adhesives. Wood
veneering and marquetry were developed, the production of animal and fish glues were refined,
and other materials were also utilized.
Adsorption Theory
The adsorption theory states that adhesion results from molecular contact between two materials
and the surface forces that develop. Adhesion results from the adsorption of adhesive molecules
onto the substrate and the resulting attractive forces, usually designated as secondary or van der
Waals forces(Butt et al., 2008). For these forces to develop, the respective surfaces must not be
separated more than five angstroms in distance. Therefore, the adhesive must make intimate,
molecular contact with the substrate surface. The process of establishing continuous contact
between an adhesive and the adherend is known as „„wetting.‟‟ Good wetting results when the
adhesive flows into the valleys and crevices on the substrate surface; poor wetting results when
the adhesive bridges over the valleys formed by these crevices(Allen, 1993). Obtaining intimate
contact of the adhesive with the surface essentially ensures that interfacial flaws are minimized
or eliminated. Poor wetting causes less actual area of contact between the adhesive and adherend,
and stress regions develop at the small air pockets along the interface (Pocius, 1997).
Theories of Adhesion
The actual mechanism of adhesive attachment is not explicitly defined. Several
theories attempt to describe adhesion. No single theory explains adhesion in a
general, comprehensive way. Some theories are more applicable for certain
substrates and applications; other theories are more appropriate for different
circumstances (Allen, 1993). Each theory has been subjected too much study,
question, and controversy. However, each contains certain concepts and
Information that is useful in understanding the basic requirements for a good bond.
The most common theories of adhesion are based on adsorption, simple
mechanical interlocking, diffusion, electrostatic interaction, and weak-boundary
layer (Pocius, 1997).
Classification of Adhesives
For the most part, adhesives used to bond wood together may be separated into two distinct
groups: those adhesives such as animal, vegetable, casein, and blood glues which are formulated
from materials of natural origin, and those adhesives which are based on synthetic resins derived
from petroleum, natural gas, and coal, i.e., products of the petrochemical and related industries
(Eckelman, 1977). The properties of various adhesives are discussed below separated according
to these two categories.
Starch Based Vegetable Adhesives
although starch glues still are used in the United States, they are used little in the wood industry.
Of particular importance, they have been replaced by urea-resin adhesives in gluing interior-type
hardwood plywood and furniture (Rieman, 1992). They are included here largely as a matter of
historical interest. As the name implies, the principal component of these adhesives is starch
which may be obtained from a variety of plants including corn, potatoes, rice and cassava. The
root of the cassava plant is the source of tapioca. Prior to World War II, extensive cassava
plantations were maintained by major glue companies in what is now Indonesia. During the war,
these plantations were lost, substitutes were found, and production of glues which relied on this
plant decreased accordingly(Williani, 1921). Vegetable glues are ordinarily sold in powdered
form and must be mixed with water. Other chemicals such as alum may be added to improve
their properties. These mixtures are heated to prepare them for use--heating flour paste, for
example, renders the flour soluble. Vegetable glues are relatively inexpensive and have a
relatively long pot life. They set through loss of water, which may be quite slow, so that glued
assemblies must often remain clamped overnight. Vegetable glues were widely used during
World War I in such applications as veneering. They lack moisture resistance, however, stain
certain veneer species, and are attacked by micro-organisms (Eckelman, 1977)
INTRODUCTION
The increase in environmental pollution as a result of the use of petroleum-based adhesive and the
increase in the demand for adhesive with limited raw material have led to the advent of the industries
looking for alternative sources or plant-based materials for the production of new, affordable, cheap and
eco-friendly adhesives.( RASĀYAN J. Chem., Vol. 14, No.3, 2021)
LITREATURE REVIEW
Production of Adhesives from Cassava Starch (N. J. Tonukari et al.)
the main raw material used in glue and adhesive industries is starch. Two things are very
necessary for an adhesive to be effective. Other desired requirements are ease of application,
reasonable setting time, resistance to moisture, aging, heat and fungal attack, non-staining and
gap filling [22]. By virtue of its good adhesive qualities, cassava starch is an important raw
material in adhesive industries.
Cassava starch has a strong film, clear paste, good water-holding properties, and stable viscosity.
Adhesives made of cassava starch are used locally in corrugation box industry, paper conversion
industry and liquid gum industry. They are made from by-products which are supposed to be
wastes, which make them have very low cost advantage. Adhesives create a bonding between the
adhesive and the product to be bonded. Locally made cassava starch has a viscous temperature of
62˚C - 68˚C, which makes it advantageous over maize. As a result, the use of caustic soda which
changes the pasting temperature of maize from about 80˚C to 65˚C in the adhesive formulation is
not required. The corrugated cardboard industry uses cassava dextrins to produce cartons, boxes
and other packing materials. The layers of board are pasted together with a suspension of raw
starch in a gelatinized solution. The board is pressed between hot rollers. This affects the
gelatinization of the raw starch and leads to a very strong bonding. Cassava dextrins in aqueous
solution re-dampen gums (used for stamps and envelopes) since they provide a high solids
solution with clean machining properties.These adhesives have applications in many industries.
For example, cassava-based adhesives in oil industries are used to improve the viscosity of
drilling muds in oil wells. Modified cassava starch (a mixture of clay) provides the bores with
the right stickiness and water-holding capacity for drilling of oil wells or water wells. It is
also used to close the walls of bore holes and prevents the loss of fluid. Cassava-based adhesives
in cement industries are presently used as an additive in cement to improve the setting time.
Cassava Flour in Plywood and Paperboard Industry N. J. Tonukari et al.)
In Nigeria, standard cassava flour can be produce and made available at a lower cost than wheat
flour. This can pilot the way to further savings on unit cost of production. The plywood and
paperboard industries simply make use of either high-grade cassava flour directly or adhesives
which consist of mixtures of flour and one or more chemicals. The industries also make use of
low quality cassava starch because they do not care about the cyanide content, microbiology,
color, taste or odor of the flour. This makes low quality cassava starch to find application
in this sector. Cassava starch is used as an adhesive to make paper produced bright and strong. It
is widely used as a tub size and beater size for producing paper. An important new application of
cassava starch in paper industries is in the machine-coating of magazine paper, formerly done
exclusively with caseins.
Other
Industrial
Applications
of
Cassava
and
Its
Waste
Products
Starch is also an essential natural resource used for manufacturing powder in the cosmetics
industries, and cassava starch plays a very important role here. Activated carbons prepared from
waste
cassava
peel
are
efficient
as
adsorbents
for
dyes
and
metal
ions.
Wastes obtained from the harvesting and processing of cassava can be used for different
purposes in various industries. A cassava starch production unit processing 100 tons of tubers per
day has an output of 47 tons of fresh by-products, which may cause environmental problems
when left in the surroundings or carelessly disposed of [23]. In Nigeria, cassava wastes are
usually left to rot away or are burnt, leaving space for more waste to be gathered. The heaps emit
carbon dioxide and produce a strong offensive smell. The use of cassava byproducts as feedstuffs
or as an alternative substrate for biotechnological processes is a positive way to alleviate
environmental issues [24]. These include cassava leaves, stems, peels and sievate. Cassava peels,
leaves and stems are often left to rot away on farms and homesteads after harvesting the roots
[25].