Clasiffication of Textile Fibers

1. TEXTILE FIBRES
What is Textile Fiber? | Types of Textile Fiber
What is fiber?
In a broad sense the word fiber is used for various types of matter – natural or manmade, forming basic
elements of textile fabrics and other textile structures. It is defined as one of the delicates, hair-like
portion of the tissues of a plant or animal. Fiber is defined by Fabric Link Textile Dictionary as The
basic entity, either natural or manufactured, which is twisted into yarns, and then used in the production
of a fabric. The physical interpretation of the word fiber is a unit of matter characterized by having a
length of at least hundred times its diameter.
What is textile fiber?
Technologists have defined the term Textile fibers as those fibers which can be spun into a yarn or
made into a fabric by interlacing, or interloping in a variety of machines including weaving, knitting,
braiding, felting, bonding, etc.
The fabric- and garment manufacturing industry is one of the most essential industries. Its raw
materials are fibers. So, in making a textile product the parameters of the basic raw material, fiber, are
very important.
The use of textiles for clothes and furnishing hinges on an exceptional combination of properties, such
as warmth, softness, and pliability. These properties depend upon the raw materials used to make these
products. Thus for a fiber to be useful for textile purposes, it should have certain properties: the fiber
length must be several hundred times the width, it must be able to be converted into yarn, and it must be
strong enough to withstand mechanical action during production. So, a textile fiber must have at least 8
mm of length so that it will be supple, flexible, and strong enough to be spun. Other properties like
elasticity, fineness, uniformity, durability, luster, and crimp should also be possessed by a textile fiber.
Types of Textile Fiber:
Generally two types of fiber.
1. Natural fiber.
2. Manmade fiber.
Natural Fiber:
Natural fibers include those produced by plants, animals, and geological processes. They are
biodegradable over time. They can be classified according to their origin.
A class name for various genera of fibers (including filaments) of:
1. Animal (i.e., silk fiber and wool fiber);
2. Mineral (i.e., asbestos fiber); or
3. Vegetable origin (i.e., cotton fiber, flax fiber, jute fiber, and ramie fiber).

2. Manmade Fiber:
It is also known as Manufactured fiber. Synthetic or man-made fibers generally come from synthetic
materials such as petrochemicals. But some types of synthetic fibers are manufactured from natural
cellulose; including rayon, modal, and the more recently developed Lyocell. A class name for various
genera of fibers (including filaments) produced from fiber-forming substances which may be:
(1) Polymers synthesized from chemical compounds, e.g., acrylic fiber, nylon fiber, polyester fiber,
polyethylene fiber, polyurethane fiber, and polyvinyl fibers;
(2) Modified or transformed natural polymers, e.g., alginic and cellulose-based fibers such as acetates
fiber and rayons fiber; and
(3) Minerals, e.g., glasses. The term manufactured usually refers to all chemically produced fibers to
distinguish them from the truly natural fibers such as cotton, wool, silk, flax, etc.e.g: Glass fiber.
Classification of Textile Fibres:
Fibers for textiles are classified by many systems. In 1960, the Textile Fiber Products Identification Act
became effective. One of the basic ways to classify fiber is by its origin, and this is indeed the most
commonly employed method. Flow chart-1 gives a general overview of fiber classification.
There are various types of fibers used in the textile industry, each having their unique properties. These
characteristics are largely dependent upon their origins. Natural fibers are obtained from nature, where
the source could be a plant, an animal, or a mineral. Regarding plants, we obtain fibers from seeds
(cotton, coir), from leaves (sisal), and from stems (jute, flax, ramie, etc.).
From animals we get wool and silk and from minerals we obtain asbestos. With the increasing
population, the demand for textiles is ever increasing and to meet these demands mankind has started to
develop fibers commonly classified as manmade fibers. Man made fibers are produced from polymer
sources, either from nature (regenerated fibers) or from synthetic polymers.

5. Properties essential to make a Fiber
Each fiber has particular properties which help us to decide which particular fiber should be used to suit
a particular requirement. Certain fiber properties increase its value and desirability in its intended end-
use but are not necessary properties essential to make a fiber.
Fiber Properties for specific requirements
The utility of fibers are broadly categorized into 2 different uses- one is Apparel or Domestic use and the
other is Industrial use. In order to be used in each of these each of these categories, the fiber has to meet
some specific requirements. They are:
Apparel/Domestic Requirements
 Tenacity: 3 – 5-gram denier
 Elongation at break: 10 – 35%
 Recovery from elongation: 100% at strains up to 5%
 Modulus of elasticity: 30 – 60-gram denier
 Moisture absorbency: 2 – 5%
 Zero strength temperature (excessive creep and softening point):
above 215°C
 High abrasion resistance (varies with type fabric structure)
 Dye-able
 Low flammability
 Insoluble with low swelling in water, in moderately strong acids
and bases and conventional organic solvents at room temperature
to 100°c
 Ease of care
Industrial Requirements
 Tenacity: 7 – 8 grad denier
 Elongation at break: 8 – 15%
 Modulus of elasticity: 80 grad denier or more conditioned, 50 grad denier wet
 Zero strength temperature: 250° C or above
Basic Textile Fiber Properties
There are several primary properties necessary for a polymeric material to make an adequate fiber.
Certain other fiber properties increase its value and desirability in its intended end-use but are not
necessary properties essential to make a fiber. Such secondary properties include moisture absorption
characteristics, fiber resiliency, abrasion resistance, density, luster, chemical resistance, thermal
characteristics, and flammability.

6. Some Primary Properties ofTextile Fibers are:
 Fiber length to width ratio,
 Fiber uniformity,
 Fiber strength and flexibility,
 Fiber extensibility and elasticity, and
 Fiber cohesiveness.
The properties of textile fiber are given below:
Normally properties of textile fiber are three types:
A) Physical Properties
B) Mechanical Properties
C) Chemical Properties
Physical Properties ofTextileFibers:
Length and length uniformity:
Length of staple fiber is one of the most important characteristics. Generally a longer average fiber
length is to be preferred because it confers a number of advantages. Because its processing is
comparatively easy from short length fiber. Besides, more even yarns can be produced from them
because there are less fiber ends in a given length of yarn and also a higher strength yarn can be
produced from them for the same level of twist.
Therearetwo types of fiberonthe basisof length:
1. Continuous filament
2. Staple fiber
Continuous filament
Long and continuous fibers are called filament. Filaments are continuous in length which can be used as
such form or cut into shorter staple fiber form. These fibers are collected from both natural and artificial
source. Any natural fiber can be made into a filament. When only one filament is used in a yarn then it is
called mono filament. When more than one filament are used in yarn then it is called multi filament.
Mono filament → 1.5 holes in spinneret.
Multi filament → 10-100 holes.
Staple fiber
When the length of fiber is short then it is called staple fiber. Stable fibers are manly shorter in length
and related to natural fiber. All natural fibers without silk can be collected as staple fiber. Artificial
fibers also collected as staple fiber.
Staple fibers are three types on the basis of length:
Short staple: Length is less than 2 inch.
Medium staple: Length is from 2-4 inch.
Long staple: Length is more than 4 inch.

7. Moisture regain:
The amount of moisture (water) present in a textile sample is referred to either by its regain or its
moisture content. These two terms are often confused with each other. Moisture regain is expressed as
the percentage of water in a sample compared to its oven dry weight, also referred to as its bone dry
weight. Moisture content is expressed as a percentage of the total weight of the sample. The standard
test method ASTM D2495-07 is most commonly employed in the textile industry to measure the regain
and moisture content. The test is a simple one and can be easily performed. A sample of fiber is
collected and weighed, before being oven dried at 105°C until it maintains a constant weight. The
difference between the original mass before drying and the oven dried mass is calculated as a
percentage, and is denoted either as moisture content or moisture regain. Moisture regain and moisture
content can be measured using the following equations.
W
R= ---------------- x100 ------------------------------ (1)
D
W
C = ---------------- x100 --------------------------------- (2)
D + W
Where,
R is the moisture regain, C is the moisture content
W is the weight of water, D is the oven dry weight
Trash content:
The presence of undesirable material in the fiber is considered to be trash. Other synonyms include
contamination and no lint matter. It is comprised of fragments of leaves, stalks, grasses, seeds, and dust.
It also includes feathers; pieces of plastic, rugs, and cloths; foreign fibrous material other than the
desired fiber (like polyester or jute in cotton); and immature fibers. The immature fibers of the same
desired fiber are also considered to be trash as they are not wanted in the final product. A Shirley
analyzer is used to determine trash content in the fibrous tuft. It comprises a pair of rollers for gripped
feeding into a saw tooth beater, rotating at a high surface speed.
Cross-sectional shape of the fiber:
Shape affects the physical and mechanical properties of textile fiber. There are many properties which
are changed by the shape of the fiber’s cross section, like flexural rigidity, fabric softness, drape,
crispness, and stiffness. Different natural fibers have different types of shapes, while the shape of man-
made fibers depends upon the shape of the spinneret from which they are extruded, as shown in Figure.
Like silk it has a triangular cross section. Cotton fibers are kidney shaped. Wool fibers are round or oval
in shape.

8. Figure: Schematic illustration of different cross-sectional shapes of fibers
Fiber color:
The color of the fiber is an important aspect in regard to aesthetic sense and dye shade. Every fiber type
has its particular color regarding its natural or synthetic origin. In natural fibers, cotton is found as white
to yellowish in color, wool fiber has whitish to blackish color grades, silk fiber is found in a lustrous
white color, and jute fiber is brown. Regenerated rayon fibers are transparent in color unless dulled by
pigments. In synthetic fibers, acrylic ones are white to off-white, nylon ones are off-white, polyester
ones are white, para-aramid ones are dull yellowish, and carbon ones are black. Some fibers can be
decolored to introduce new colors by the dying process, while other fibers have a permanent color which
can’t be removed, as in the case of Kevlar and carbon fibers.
Fiber fineness:
Fineness is one of the major aspects of fiber characteristics and explains cross-sectional thickness. A
fine fiber can be used to spin fine yarns. As the linear density of yarn decreases, the number of fibers
also decreases by yarn diameter. The presence or absence of a single fiber shows longitudinal
unevenness and variation in diameter. The decrease of fiber diameter will increase the number of fibers
in a cross section of yarn and hence better yarn evenness can be achieved.
Fiber fineness has great influence on the properties of yarn and fabric. The evenness of the yarn is

9. improved by the use of fine fibers. In addition, fine fibers need less twist and have less stiffness than
coarser fibers. The increase in fiber surface due to a decrease in fiber diameter contributes to a cohesion
of fibers to achieve the same strength with less twist than coarser fibers. These characteristics contribute
to the hand feel of the products developed from them.
Fiber crimp:
The waviness in a fiber is known as crimp. It is measured as the number of crimps or waves per unit
length or the percentage increase in the extent of the fiber on removal of the crimp. Crimps also govern
the capacity of fibers to cohere under light pressure. The bi-component structure of wool increases the
crimp in it. Cotton has a low crimp. Crimp allows the scattering of light due to its wavy structure and
provides a dull appearance on developed products. Synthetic fibers are lustrous in structure, which can
be reduced by the introduction of crimps in them. Crimps increase the thickness and enhance the bulky
aspect of products.
Luster:
It is seen when light reflected from a surface. It is more subdued than shine.Silk and synthetics have
luster than cellulosic fibres. Infact synthetics have highluster which is purposefully removed during
spinning.
Static Electricity:
It is generated by the friction of a fabric when it is rubbed against itself orother objects. If the electrical
charge that is not conducted away, It tends tobuild up on the surface and when fabric comes in contact
with a good conductora shock or transfer occurs. This transfer may sometimes produce sparks. This
is more feel during hot and humid conditions.
Mechanical Properties of Textile Fiber
Fiber strength:
Strength of any material is derived from the load it supports at break and is thus a measure of its limiting
load bearing capacity. Normally strength of a textile fiber is measured in tension when the fiber is
loaded along its long axis and is designated as Tensile strength.
The strength and elongation of a cotton fiber can be measured by a single fiber or by the bundle method.
The bundle fiber strength can be measured using an ASTM standard test procedure that employs a fiber
bundle tensile testing machine. These machines are commercially available in pendulum and inclined
plane mechanisms. A fiber sample is conditioned as per the standard conditioning procedure.

10. Frictional properties:
Frictional properties are due to the friction between the fibers. These properties are shown during
processing. Too high friction and too low friction is not good for yarn. Therefore it is an important
property when yarn manufacturing and processing.
Flexural properties:
It is the property or behavior shown by the fiber or material when we bend it. The importance of
Flexural properties is required when we wear cloth.
Tenacity:
Tenacity is the measure of the breaking strength of a textile fiber. It is also defined as ultimate breaking
strength and is the maximum force a fiber can bear without breakage. The tenacity value for individual
fibers is the value of load applied at breakage. The specific stress is the ratio of load to linear density and
is measured in units of g/denier, cN/tex, and MPa.
Breaking extension:
The elongation necessary to break a textile material is a useful quantity. It may be expressed by the
actual percentage increase in length and is termed as breaking extension.Mathematically, Breaking
extension (%) = (Elongation at break / Initial length) × 100%
Work of rupture:
Work of rupture is defined as the energy required to break a material or total work done to break that
material. Unit: Joule (J)
Initial modulus:
The tangent of angle between the initial curve and the horizontal axis is equal to the ratio of stress and
strain.
In engineering science the ratio is termed as Young’s Modulus and in textile we use the terms as Initial
Young’s Modulus.
Initial modulus, tan α = stress / strain. Tan α ↑↓ → extension ↓↑

11. Stress-When some external force acts on a body, it undergoes some deformation. As the body
undergoes some deformation, it set up some resistance to deformation. This resistance per unit area to
deformation is called stress.
Strain-Strain is the term related to the stretched or elongation with the initial length. The deformation
per unit length is known as strain
Elastic recovery:
The power of recovery from a given extension is called elastic recovery. Elastic recovery depends on
types of extension, fiber structure, types of molecular bonding and crystalline of fiber. The power of
recovery from a given extension is called elastic recovery. Elastic recovery dependson types of
extension, fiber structure, types of molecular bonding and crystalline of fiber.
Creep:
When a load is applied on the textile material an instantaneous strain is occurred, but after that the strain
will be lower with the passing time. This behavior of the material is termed as creep.
There are two types of creep:
i) Temporary creep:
This type of creep is temporarily occurred in fiber. So, after removing load it is
possible for textile fiber to recover its original shape. Here, elastic deformation is occurred and fibre
does not break, only molecular chains of fiber get stretched.
ii) Permanent creep:
This type of creep is permanently occurred in fiber. So, after removing load it is not
possible for textile fiber to recover its original shape. Here, plastic deformation is occurred and
molecular chains of fiber break, hence the whole fiber breaks.
Here,
AB = initial length of the specimen
AD = final length after recovery
BD = total extension
CD = elastic extension
BC = plastic extension
Total extension = Elastic extension + Plastic extension
So,Elastic recovery (%) = (Elastic extension/total extension) ×100% = (CD/BD) × 100%
So, Plastic recovery = (plastic extension/total extension) ×100% = (BC/BD) ×100%

12. Chemical Properties of Textile Fiber
Blend ratio:
Blending is the easiest way to obtain synergistic effects of two different materials. In the textile industry
the blending of a fiber is a common practice to obtain the desired functional and aesthetic properties.
Blends can be identified either qualitatively or quantitatively. Furthermore, the testing methods for the
identification of fibers in a blend can be technical or nontechnical.
The nontechnical tests include the feeling test or the burning test; these tests are for qualitative
assessment.
Maturity ratio:
The maturity of the cotton fiber is analyzed using the ASTM standard test procedure by employing
polarized light or the sodium hydroxide swelling technique. A solution of 18% concentration of sodium
hydroxide is used to swell the cotton fibers by soaking them. The fibers are then laid parallel on the
microscope slide and covered with glass and viewed at a magnification of 400× to distinguish between
immature and mature fibers. The mature fibers swell to become almost round in cross-sectional shape.
This method is not considered acceptable for commercial testing due to the poor precision of the results
between different laboratories.
Effects of Acid, Alkali:
Acid or alkali is harmful for cellulose and protein fibers. Therefore, the effect of acid and alkali must be
known during bleaching, dyeing and finishing. Different fibers react differently with acid and alkali. For
example, Cotton and Linen damaged when they are subjected to conc. Hydrochloric, Sulphuric and
Nitric acids. Also dilute solution of those acids can make harm to the fibers. On the other hand, conc.
alkaline solution is not harmful to Cotton and Linen. Wool is not affected by dilute solution of acid. But
conc. acid and alkali damage wool easily. So acid or alkali must be chosen properly to use in different
purpose and processing.
Effects of Water:
Water is very important to determine the properties of fibers. According to the behaviors of fibers with
water, fibers are classified into two groups – hydrophobic and hydrophilic. Water is used in process like
scouring, dyeing etc.
Effects of Heat:
Effect of heat is a vital point during dyeing, ironing, steaming and some other operations. Different
fibers behave differently under heat. Some fibers burn when heat is applied. Some fibers are not
combustible e.g. mineral fiber, glass fiber etc. Cotton is easily flammable, wool is hardly flammable
fiber.

13. Effects of Sunlight:
When we wear cloth or fabric it comes into the touch of sunlight. It is very familiar to us. Effect of
sunlight should be kept in mind for general people. Sunlight reduces the strength of cotton and it
becomes yellow. Linen is better than cotton in sunlight. But cotton is better than silk.
Effect of Biological agent:
If the fibers are attacked by bacteria’s, black spots are seen on the fibers as a result of which the strength
of fiber is reduced. Its importance whether fibers attached by micro-organisms or not upon which
strength of products depends. Cotton, Linen and rayon are attacked by fungus. Silk, wool, acetate, tri-
acetate and spandex have better resistance to mildew and other insects.
Chemical composition:
The chemical composition of fibers depends on their origin. Natural fibers obtained from plants are
made up of cellulosic structures like cotton, jute, and hemp fibers. The fibers obtained from animals are
composed of amino acids like wool and silk. Regenerated fibers have the same chemical composition as
those obtained from their parent origin, like viscose rayon which is cellulosic in nature. The chemical
composition of synthetic fibers is based on the nature of their raw materials and the chemical reactions
that occurred.

14. An Overview on Physical and Chemical Properties of Natural Fibre and Their Applications in
Textile
INTRODUCTION
Textile fibre is the material obtained from natural or synthetic source. Fibre which are obtained from
natural source are mainly termed as natural fibre, as they are originated from natural source, there are
three main source from that natural fibre can be produced. Cellulose fibre (origin from plant), protein
fibre (origin from animal) and also mineral fibre.This three kinds of fibre could produces staple yarn
(short fibre) in which fibre length is not too longer as compared to that of synthetic fibre. A natural
fibre may further defined as an agglomeration of cells in which diameter is negligible in comparison
with length. Although natural fibre material, specially cellulosic type such as cotton, in which number
can be used for for textile products and other industrial purpose. Apart from economical consideration,
usefulness of fibre for commercial purpose is determined by properties of fibre like length, strength,
pliability, elasticity abrasion resistance, absorbency and various surface property. hence study of fibre
property is important. Natural fibre are classified according to their origin. Vegetable or cellulose base,
class includefibre such as cotton, flax, and jute. The animal or protein based fibre include wool, mohair
and silk. An important class in mineral class is asbestos. Study of fibre property is important because
properties of fibre are mainly concerned with internal and surface structure of fibre and both are control
the behaviour of fibre in yarn and fabric.
1. COTTON FIBRE
Cotton fiber is the purest source of cellulose and the most significant natural fiber. It is more popular
for its variety of use. Cotton fibre is most used fibre for producing various type of fabric through all over
the world. Cotton fabric are comfortable to wear because of their unique fibre property. It has its own
physical and chemical property which give better processing I spinning, weaving, knitting, dyeing,
printing and finishing.
Fig: Cotton fiber

15. Characteristics of Cotton:
Good moisture absorbency
1. Non-allergic
2. Good heat resistance
3. Good washing endurance (can be boiled and chlorinated)
4. Soft feel
5. Shrinkage tendency
6. Crimping tendency
7. Medium dyeing fastness
Macro Structure of Cotton Fiber:
Under a microscope, a cotton fiber appears as a very fine, regular fiber. It ranges in length from about
10mm to 65 mm, depending upon the quality of the fiber. Cotton is a very fine fiber with little variation
in fiber diameter; compared with wool for instance, its fiber diameter is not considered as critical a fiber
dimension as its length. The fiber length to breadth ratio of cotton ranges from about 6000:1 for the
longest and best types, to about 350:1 for the shortest and coarsest cotton types. The greater this ratio,
the more readily can the cotton fibers be spun into yarn. Cotton fibers vary in colour from near white to
light tan.
Structure of Cotton fiber

16. RAW COTTON COMPONENTS:
Composition of a Fiber Composition
of the
Cuticle%
Constituent Typical% Low% High%
Cellulose 94.0 88.0 96.0
Protein (N-6.25) 1.3 1.1 1.9 30.4
Pectic substances 0.9 0.7 1.2 19.6
Wax 0.6 0.4 1 1.0 17.4
Mineral matters 1.2 0.7 1.6 6.5
Maleic, citric, and
other organic acids 0.8 0.5 1.0
Total sugars 0.3
Cutin 8.7
Components Composition % Ranges
Cellulose 80-90%
Water 6-8%
Waxes and fats 0.5 - 1%
Proteins 0 - 1.5%
Hemicelluloses, pectin &
Others 4 - 6%
Ash 1 - 1.8%
Physical property of cotton fiber:
Length of cotton fiber:Physically the individual cotton fibres consist of a single long tubular cell. Its
length is about 1200-1500 times than its breadth. Length of cotton fibre varies from 16mm to 52 mm
depending upon the type of cotton.
 Indian cotton- 16-25 mm
 American cotton- 20-30 mm
 Sea Island- 38-52 mm
 Egyptian cotton- 30-38 mm

17.  Fineness of cotton fiber: Longer the fibre, finer the fibre in case of cotton fibre. It is expressed
in term of decitex and it varies from 1.1 to2.3 decitex.
 Indian= 2.2-2.3dtex
 American= 2.1-2.2 dtex
 Egyptian= 1.2-1.8 dtex
 Sea Island= 1.0-1.1 dtex
 Tensile strength – cotton is moderately strong fibre. Tenacity of cotton fibre is lies between 3-5
gm/denier
 Breaking elongation - 8-10%
 Specific gravity – 1.54 gm/cc
 Moisture regain – standard is 8.5
 Color – normally the color of cotton is creamy white
Chemical property of cotton fiber:
 Effect of acid- Concentrated acid such as sulphuric acid and hydrochloric acid damages the fibre.
But weak acid not damages the fibre.
 Effect of alkali – Alkali does not damages the fibre
 Effect of organic solvent – Cotton is dissolve in concentrated 70% H2SO4
Maturity of Cotton:
The maturity of cotton is defined in terms of the development of cell wall. A fully mature fiber has a
well developed thick cell wall. On the other hand, an immature fibre has a very thin cell. The fibre is to
be considered as mature fibre when the cell wall of the moisture-swollen fibre represents 50-80% of the
round cross section, as immature when it represents 30-45% and as dead when it represents less than
25%.
Cotton fiber structure

18. Immature fiber leads to :
 Nepping,
 Loss of yarn strength,
 Varying dye ability,
 High proportion of short fibres,
 Processing difficulties mainly at the card
Mature fibre → Dye absorb↑
Immature fibre → Dye absorb ↓.
Application of cotton:
1. Shirts
2. Blouses
3. Childrens wear
4. Swimwear
5. Suits
6. Jacket
7. Skirts
8. Pants
9. Sweaters
10. Hosiery
11. Table cloths
12. Table mats
13. Napkins
2. WOOL FIBRE
Wool is second most important fibre of animal origin. it is keratinous type of protein base fibre. Major
amount of wool is produced in australia and New zealand. Wool fibre possesses a feature called
‘crimp’, which is permanent wave. and fine wool are more crimpy.
Fig: Wool fibre

19. Features:
 Coarse and hair like.
 Have relatively fewer scales and very little crimp.
 Smoother and have more lusture.
 Used for carpet, rugs and low grades fabrics.
A morphological diagram of a wool fiber:
Fig: Morphological diagram of a wool fiber
The micro structure of wool consists of three main components:
1. The cuticle
2. Cortex
3. Fibrils.

20. 1) The cuticle:
The cuticle is the layer of overlapping epithelial cells surrounding the wool fiber. It consists of the
epicuticle, exocuticle and endocuticle.
The epicuticle is the outermost layer which covers the wool fiber. It is only few molecules thick and
composed of a water repellent, wax-like substance.
The overlapping epithelial cells form the exocuticle. An epithelial cell is about 1 long and 36 wide.
The epithelial cells are largely responsible for the felting shrinkage of untreated wool textile materials.
The endocuticle is an intermediate cementing layer bonding the epitheial cells to the cortex of the wool
fiber.
2) Cortex:
The cortex of wool fiber forms about 90% of the fiber volume. It consists of countless long, spindle-
shaped cells. If a specially selected dye is applied to the fiber and the fiber cross-section examined, the
ortho and para cortex become apparent. The ortho cortex absorbs more dye than para cortex. The cortex
of the wool fiber is composed of two distinct sections.
a) Ortho-cortex, b) Para-cortex.
The ortho and para cortex spiral around one another, along the length of the wool fibre.
3) Fibril:
The cortical cells of the wool fiber consists of a number of macro fibrils each about 100-200 nm in
diameter. The macro fibrils are held together by a protein matrix. Each macro fibrils consists of
hundreds of micro fibrils, each about 5nm in diameter. Each micro fibril consists of eleven photos fibrils
about 500nm in length and 2nm in diameter. Finally, each photo fibril consists of three wool polymers,
which also spiral around each other.
Why ortho-cortex absorbs more dye than the para-cortex?
The ortho-cortex absorbs more dye than the para-cortex. The reason for this different staining is the
different composition of the para-cortex and the ortho-cortex. The chemical composition of the para-
cortical cells shows a higher cystine (cystine is a sulpher containing amino acid, capable of forming
disulphide cross-links) content than the ortho-cortical cells.
Since there is a greater amount of cystine in the para cortical cells, a greater number of disulphide cross
links exist in the para-cortex. This increased cross-linking tends towards greater chemical stability
resulting in less dye absorption.

21. Why wool fiber is easy to dye?
Wool is a protein fiber which has more amorphous region than crystalline region. So dye molecules can
easily enter to the amorphous region of the fiber. Moreover wool is more absorbent in nature. So, wool
is easy to dye.
Why wool is fine to wear?
Due to helical configuration of ortho and para cortex, wool fiber has a smoothness, flexibility, elasticity
and more durability. So we can say that wool fiber has higher resiliency properties. That is why wool
fiber is fine to wear.
Macro structure of wool:
The wool fiber is a crimp, fine to thick, regular fiber. As the diameter of wool fiber increases, the
number of crimps per unit length decreases. A single wool fiber is rod like and tapers from the root end
to its tip.
1. Length: 5-35cm
2. Diameter:
 Fine 14
 Coarse 45
3. Length width ration:
 Fine short- 2500:1
 Long coarse- 75:1
4. Color:
Off white, light cream.
5. Crimp
10 per centimeter
Physical Properties of Wool:
01. Tenacity:
8.8-15 CN/Tex (1.0-1.7gm/den) in dry state and 7-14 CN/Tex (0.8-1.6gm/den) in wet.
02. Elongation:
25-35% under standard conditions and 25-50% when wet.

22. 03. Elastic properties:
It has an elastic recovery of 99% at 2% extension and 63% at 20% extension.
04. Specific Gravity of wool:
1.32 and so fabrics feel lighter than cellulose.
05. Resiliency:
Higher and so resist wrinkling.
06. Hygroscopisity:
Higher
07. Cross section:
Oval to roughly circular.
08. Appearance and colour:
Appearance depends on colour, long and smooth fiber characterized by two features. Sometimes
microscopically shows dark in the middle. This kemp, which are hair like character. By selective
breeding kemp can be minimized.
Chemical properties of Wool:
01. Effect of moisture:
Wool absorbs moisture to a greater extent than any other fiber and yield up readily to the
atmosphere. Under ordinary conditions wool will hold 16-18% of it weight of moisture. Wool loses
about 40% of its strength and silk loses about 15% in wet condition.
02. Effect of acids:
Wool is attacked by hot concentrated sulphuric acid and decomposes completely. It is in general
resistant to other mineral acids of all strength. Even at high temperature, though nitric acid tends to
cause damage by oxidation. Dilute acids are used for removing cotton from the mixture of two
fibers.
03. Effect of alkalis:
The chemical nature of wool keratin is such that it is particularly sensitive to alkaline substances.
Wool will dissolve in caustic soda solutions that would have little effect on cotton. The scouring and
processing of wool is carried out under conditions low alkalinity (NaOH, NaCO3). Ammonium
Carbonate, borax and sodium phosphate are mild alkalis that have a minimum effect on wool.

23. 04. Effect of organic solvents:
Wool has a good resistance to dry cleaning and other common agents.
05. Effect of bleaches:
Wool fibrion is attacked by oxidizing agents or bleaches such as H2O2, NaOCl, calcium
hypochlorite Ca(OCl)2 , KMnO4, K2Cr2O7, O3, NaCl. Wool becomes yellowish in sodium
hypochloride (NaOCl) and dissolve. It is less harmed by reducing agents or bleaches such as ZnO,
SnCl2, SO2, H2S and FeSO4.
06. Effect of sunlight:
The keratin of wool decomposes under the action of sunlight. The sulphur in wool is converted into
sulphuric acid so the fiber becomes discolored and develops a harsh feel. It losses its strength and the
dyeing properties are affected. Tends to yellow white or dull color or surface polymer degraded by
ultraviolet radiation.
Thermal properties of Wool:
Wool becomes weak and losses its softness when heated at the temperature of boiling water for long
periods of time. At 1300C, it decomposes and turns to yellow and it damages at 3000C. Wool doesn’t
continue to burn when it is removed from a flame. Do not burns readily is self extinguishing, have
odor of burning hair and have a black crushable ash.
Biological properties of Wool:
Wool is attacked by moth-grubs and by other insects. Wool has a poor resistance to mildews and
bacteria and it is not advisable to leave for too long in a damp condition.
End uses of wool:
1. Knitted apparels,
2. Suiting, over coat, sweater,
3. Carpet, lining fabric,
4. Lustrous dress,
5. Designs for curtain,
6. Blanket,
7. Hosiery fabric,
8. Home uses furnishing fabric

24. 3. JUTE FIBRE
Jute is a natural fiber popularly known as the golden fiber. It is one of the cheapest and the strongest of
all natural fibers and considered as fiber of the future. Jute occupies second place next to cotton in
worlds production of natural fibre.
Fig: Jute fibre
Physical properties of jute fibre:
 Fibre length - 50 to 300 mm
 Fibre diameter - 0.035 to 0.14 mm
 Specific gravity- Density - 1.48 gm/cc
 Fibre denier - 6 to 50
 Tenacity - 2.7 to 5.3 gm/tex
 Breaking elongation - 0.8 to 1.8 %
 Moisture regain - 13 %
 L:D - 110 to 140
 Unit cell length 0.8 to 6 mm
 Traverse swelling in water - 20 to 22 %
Chemical properties of jute fibre:
1. Chemical composition
 Cellulose - 58-63%
 Hemicellulose - 20- 22%
 Lignin - 12 - 14.5 %

25.  Wax and fats - 0.4 -0.8%
 Pectin - 0.2 -0.5 %
 Protein - 0.8 - 2.5 5
 Mineral matter - 0.6 -1.2%
2. Prolonged heating causes degradation of jute fibre.
3. Action of acid - strong acid at boiling causes hydrocellulose and lead to loss in strength. But dilute
acid have no effect on jute fibre.
4. Action of alkali- Dilute alkali has no effect of jute fibre, but strong alkali at boil causes loss in
strength.
Application jute fibre:
1. Industrial textile
 Tarpaulin
 Jute geotextile
2. Apparel textile
 outerwear
 suits
 hessian cloth
3. Home textile
 floor covering
 carpets
 upholstery
 chair covering
 curtains

26. 4. SILK FIBRE
Silk is natural protein fibre, some forms of which can be woven into textile. The protein fibre of silk is
mainly composed of fibroin and is produced by certain insect larvae to form cocoon. The best known
silk is obtained from cocoons of the larvae mulberry silkworm bombyxmori reared in captivity
(sericulture). The shimmering appearance of silk is due triangular prism like structure of silk fibre,
which allows the silk cloth to refract incoming light at different angle, thus producing different colour.
Indian silk industries are very ancient mainly in cottage right from cocoon production to fabric. India is
only one country which produces commercially available four varieties of silk i.e mulberry, tasar, Eri
and muga.
Fig: Silk fibre
Physical properties of silk fibre:
1. Length - silk is longest fibre of about 1000 mt ( unbroken filament )
2. Diameter - 0.013 to 0.08 mm
3. Denier - 2.3 ( raw state ) and 1 to 1.3 ( Boiled state )
4. Microscopy-
 cross section - Elliptical
 longitudinal view - Rough surface
6. Moisture regain - 11% at 65 % R.H and 27 c
6. Tensile strength - 3 to 4.5 gram per denier
7. Elongation - 18 to 22 %
8. Electrical property - poor conductor of electricity and accumulation of static charge.
9. Density - 1.33 gm/cc ( Raw state ) and 1.25 gm/cc ( Boiled state )

27. Chemical properties of silk fibre:
1. Action of heat - At 170 c silk is rapidly disintegrated. On burning it liberates and colour similar to
burning of hair.
2. Action of acid - Lusture of the silk increases as it absorb the dilute acid. It can decomposed by
strong mineral acid. Conc. acid such as sulphuric acid and hydrochloric acid dissolve the silk.
3. Action of Alkali - silk is not sensitive to dilute alkali but strong caustic alkali dissolve the silk.
4. Effect of organic solvent - Cleaning solvents and spot removing solvents like carbon tetrachloride,
Acetone etc. do not damage the silk.
5. Effect of sunlight - sunlight tend to accelerate the decomposition of silk. It increases oxidation and
result in fibre degradation.
Biological property of silk:
Silk is resistance to attack by mildew, other bacteria, and fungi. It is decomposed by rot producing
conditions
Applications of silk:
➢Home textile
 Decorative curtains
 Upholstery
 Silk throws and pillows
➢Apparel textile
 Silk sarees
 Decorative outerwear
➢Medical textile
 Absorbent pad
 Wound contact layer