1. Fibre Introduction

Fibre Although the word “Textile: was originally used to define a woven fabric and the processes

involved in weaving, over the years the term has taken on broad connotations, including the

following;

1. Staple fibres and filaments for use in yarns or preparations of woven, knitted, tufted,

or nonwoven fabrics,

2. Yarns made from natural or man-made fibres,

3. Fabrics and other products made from fibres or from yarns, and

4. Apparel or other articles fabricated from the above, which retain the flexibility and

drape of the original fabrics.

This broad definition will generally cover all the products produced by the textile industry

intended for intermediate or final products.

Textile fabrics are planar structures produced by interlacing or by entangling yarns or fibres

in some manner. In turn, textile yarns are continuous strands made up of textile fibres, and

the fibre is the basic physical structure or element which makes up textile products.

Fibres : A unit of matter characterized by flexibility, fineness and a high length to

width ratio

Staple fibre : A fibre of definite length (usually 10-500 mm)

Filament : A fibre of indefinite length

Microfibers : Microfibers are generally defined as fibers of less than one denier per

filament (dpf). Super-micro fibers are less than 0.3 dpf. Microfibers can generally be

produced by direct spinning methods, while super-micro fibers sometimes require bi-

component technology for production.

• Comparisons

Human Hair 30-50 dpf

Wool 4-6 dpf

Cotton 1.4 -1.6 dpf

Silk 1.1 -1.2 dpf

Microfibre less than 1.0 dpf

Super-microfibre less than 0.3 dpf

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Each individual fibre is made up of millions of individual long molecular chains of discrete

chemical structure. The arrangement and orientation of these molecules within the

individual fibre, as well as the gross cross section and shape of the fibre (morphology), will

affect fibre properties, but by far the chemical structure of the long molecular chains which

made up the fibre will determine the basic physical and chemical nature of that fibre.

Usually, the polymeric molecular chains found in the fibres have a definite chemical

sentence which repeats itself along the length of the molecule. The total number of units

which repeat themselves in a chain (n) varies from a few units to several hundred and is

referred to as the degree of polymerization (DP) for molecules within that fibre.

Fibre Properties

There are several primary properties necessary for a polymeric material to make an adequate

fibre; 1) fibre length to width ratio, 2) fibre uniformity, 3) fibre strength and flexibility, 4)

fibre extensibility and elasticity and 5) fibre cohesiveness

Certain other fibre properties increase its value and desirability in its intended end-use but

are not necessary properties essential to make a fibre. Such secondary properties include

moisture absorption characteristics, fibre resiliency, abrasion resistance, density, luster,

chemical resistance, thermal characteristics, and flammability.

Primary Properties

Fibre Length to Width Ratio

Fibrous materials must have sufficient length so that they can be made into twisted yarns. In

addition, the width of the fibre (the diameter of the cross section) must be much less than the

overall length of the fibre, and usually the fibre diameter should be 1/100 of the length of the

fibre. The fibre may be infinitely long, as found with continuous filament fibres, or as short

as 0.5 inches as found in staple fibres. Most natural fibres are staple fibres, whereas man-

made fibres come in either staple or filament form depending on processing prior to yarn

formation.

Fibre Uniformity

Fibres suitable for processing into yarns and fabrics must be fairly uniform in shape and

size. Without sufficient uniformity of dimensions and properties in a given set of fibres to

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be twisted into yarn, the actual formation of the yarn may be impossible or the resulting yarn

may be weak, rough, and irregular in size and shape and unsuitable for textile usage.

Fibre Strength and Flexibility

A fibre or yarn made from the fibre must possess sufficient strength to be processed into a

textile fabric or other textile article. Following fabrication into a textile article, the resulting

textile must have sufficient strength to provide adequate durability during end-use.

The strength of single fibre is called the tenacity, defined as the force per unit linear density

necessary to break known unit of that fibre. The breaking tenacity of a fibre may be

expressed in grams per denier (g/d) or grams per tex (g/tex). Many experts consider single

fibre strength of 5 grams per denier to be necessary for a fibre suitable in most textile

application, although certain fibres with strengths as low as 1.0 grams per denier have been

found suitable for some applications.

A fibre must be sufficiently flexible to go through repeated bending without significant

strength deterioration or breakage of the fibre. Without adequate flexibility, it would be

impossible to convert fibres into yarns and fabrics, since flexing and bending of the

individual fibres is a necessary part of this conversion. In addition, individual fibres in a

textile will be subjected to considerable bending and flexing during end-use.

Fibre Extensibility and Elasticity

An individual fibre must be able to undergo slight extensions in length (less than 5%)

without breakage of the fibre. At the same time the fibre must be able to almost completely

recover following slight fibre deformation. In other words, the extension deformation of the

fibre must be nearly elastic. These properties are important because the individual fibres in

textiles are often subjected to sudden stresses, and the textile must be able to give and

recover without significant overall deformation of the textile.

Fibre Cohesiveness

Fibres must be capable of adhering to one another when spun into a yarn. The cohesiveness

of the fibre may be due to the shape and contour of the individual fibres or the nature of the

surface of the fibres. In addition, long-filament fibres by virtue of their length can be

twisted together to give stability without true cohesion between fibres. Often the term

“spinning quality” is used to state the overall attractiveness of fibres for one another.

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Secondary Properties

Moisture Absorption and Desorption

Most fibres tend to absorb moisture (water vapour) when in contact with the atmosphere.

The amount of water absorbed by the textile fibre will depend on the chemical and physical

structure and properties of the fibre, as well as the temperature and humidity of the

surroundings. The percentage absorption of water vapour by a fibre is often expressed as its

moisture regain.

Fibres will vary greatly in there regain, with hydrophobic (water repelling) fibers having

regains near zero and hydrophilic (water seeking) fibres like cotton, and wool having regains

as high as 15% at 21°C and 65% relative humidity.

The low regain found for many man-made fibres makes them quick drying, a distinct

advantage in certain applications. Fibres with high regains are often desirable because they

provide a “breathable” fabric which can conduct moisture from the body to the outside

atmosphere readily, due to their favourable moisture absorption-desorption properties. The

tensile properties of fibres as well as their dimensional properties are known to be affected

by moisture.

Fibre Resiliency and Abrasion Resistance

In consumer use, fibres are often placed under stress through compression, bending, and

twisting (torsion) forces under variety of temperature and humidity conditions. If the fibres

within the fabric posses good elastic recovery properties from such deformative actions, the

fibre has good resiliency and better overall appearance in end-use. For example, cotton and

wool show poor wrinkle recovery under hot moist conditions, whereas polyester exhibits

good recovery from deformation as a result of its high resiliency.

Resistance of a fibre to damage when mobile forces or stresses come in contact with fibre

structures is referred to as abrasion resistance. If a fibre is able to effectively absorb and

dissipate these forces without damage, the fibre will show good abrasion resistance. The

toughness and hardness of the fibre is related to its chemical and physical structure and

morphology of the fibre and will influence the abrasion of the fibre.

Luster

Luster refers to the degree of light that is reflected from the surface of a fibre or the degree

of gloss or sheen that the fibre possesses. The luster of a fibre is directly related to the

percentage of light reflected from the fibres when light is shined on it. The inherent

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chemical and physical structure and shape of the fibre can affect the relative luster of the

fibre.

Resistance to chemicals in the Environment

A textile fibre to be useful must have reasonable resistance to chemicals it comes into

contact within its environment during use and maintenance. It should have resistance to

oxidation by oxygen and other gases in the air, particularly in the presence of light, and be

resistant to attack by micro-organisms and other biological agents. Many fibres undergo

light induced reactions, and fibres from natural sources are susceptible to biological attack,

but such deficiencies can be minimized by treatment with appropriate finishes. Textile

fibres come in contact with a large range of chemical agents on laundering and dry cleaning

and must be resistant from attack under such conditions.

Density

The density of a fibre is related to its inherent chemical structure and the packing of the

molecular chains within that structure. The density of a fibre will have a noticeable effect

on its aesthetic appeal and its usefulness in given applications.

Thermal and Flammability Characteristics

Fibres used in textiles must be resistant to wet and dry heat and must not ignite readily when

coming in contact with a flame, and ideally should self-extinguish when the flame is

removed. Heat stability is particularly important to a fibre during dyeing and finishing of

the textile and during cleaning and general maintenance by the consumer. Textile fibres for

the most part are made up of organic polymeric materials containing carbon and burn on

ignition from a flame or other propagating source. The chemical structure of a fiber

establishes its overall flammability characteristics, and appropriate textile finishes can

reduce this degree of flammability.

Fibre Classification

Textile fibres are normally broken down into two main classes, natural and man-made

fibres. All fibres which come from natural sources (animal, plants etc.) and do not require

fibre formation or reformation are classed as natural fibres. Natural fibres include the

protein fibres such as wool and silk, the cellulose fibres such as cotton and linen, and the

mineral fibre asbestos. Man-made fibres are fibres in which either the basic chemical units

have been formed by chemical synthesis followed by fibre formation or the polymers from

natural sources have been dissolved and regenerated after passage through spinnerets to

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form fibres. Those fibres made by chemical synthesis are often called synthetic fibres, while

fibres regenerated from natural polymer sources are called regenerated fibres or natural

polymer fibres. In other words, all synthetic fibres and regenerated fibres are man-made

fibres, since man is involved in the actual fibre formation process. In contrast, fibres from

natural sources are provided by nature in ready-made form. These categories are shown in

following Table A.

Table A: General fibre Classification

Natural fibres

Cellulosic Protein Mineral

Cotton (seed hair) Wool Asbestos

Flax (bast) Silk

Jute (bast) Mohair

Sisal (leaf) Cashmere

Ramie (bast) Other animal hairs

Man-made fibres

Regenerated Modified Synthetic Mineral

Viscose rayon Cellulose diacetate Polyamide Glass

Cupra ammonium Cellulose triacetate Polyester Steel

Rayon Polyacrylic Carbon

Polyolefin

Polyvinyl

Elastane

Cellulosic Fibres

This category includes by far the most important textile fibre, cotton, which makes up nearly

50% of the total weight of fibres used in the world. Growing cotton is very important

economically to many countries which export the fibre in return for foreign currency. In

addition, they can use the seed oil for cooking and the remainder of the plant for animal

feeds. The cotton fibre is the seed hair of the cotton plant. Other cellulosic fibres are

extracted from alternative parts of plants.

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The bast fibres, flax, jute and ramie, are extracted from the stems of particular plants by a

controlled rotting process known as retting. Jute is used mainly for packaging material and

flax, which is known as linen, is used for specialty fashion fabrics. Sisal comes from the

leaves of the plant.

• Composition of cotton

– 87 to 90% cellulose; 5 to 8% water; remainder is natural impurities

• Physical Properties

Length 1/8 to 2 ½ inches; American Upland: 15/16 to 1 3/8 inches; Pima: 1 3/8

to 2 ½ inches

Color White, cream, gray, brown

Luster Very little unless mercerized

Strength-Dry

(grams/denier)

3.0 – 5.0

Strength-Wet

(grams/denier)

3.3 - 6.0

Extensibility 3 - 10%

Elasticity 75% recovery at 2% extension

Resiliency Low

Moisture Regain @

70F, 65% rh

8.5%

Flammability Burns when exposed to flame and continues to burn when flame is

removed

Electrical

Conductivity

Does not build up static charges

Specific Gravity 1.54

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• Thermal properties

– Does not melt

– Decomposes slowly upon exposure to dry heat above 300°F

– Decomposes rapidly above 475°F

• Chemical properties

– Easily damaged by strong acids

– High resistance to alkalies

– Loses strength under prolonged exposure to ultraviolet rays of sunlight

Protein Fibres

These fibres make up a small proportion of the market by weight but a much higher

proportion by value. The major fibre in this category is wool with its crimp and excellent

elasticity giving woolen fabrics valued properties. Silk is only available on a small scale but

is priced as the only natural filament fibre. Other animal hair fibres such as mohair,

cashmere and vicuna are only produced on a small scale but are sold at very high prices.

• Composition Wool fibre

– Protein fiber


Length 1 – 2 inches; most wool fibers are 1 – 8 inches; 1 – 3 inches

in woolen yarns; 4 – 8 inches in worsted yarns

Color Off-white to brown or black

Luster Low; wool fibers with more crimp are lower in luster

Strength-Dry (grams/denier) 1.0 – 1.7

Strength- Wet (grams/denier) 0.8 – 1.6



Resiliency High

Moisture Regain @ 70F,65% rh 13 - 16%

Flammability Burns slowly and is self-extinguishing

Electrical Conductivity Poor conductor; builds up static charges


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– Becomes weak when heated in boiling water for prolonged times

– In dry heat above 266°F begins to decompose and yellow


– Not easily damaged by acids

– Very easily attacked by alkalies

– Weakened by sunlight

• Composition of Silk fiber

– Protein fiber


• Length • 300 – 600 meters

• Color • Off-white to cream, yellow, or brown

• Luster • High

• Strength- Dry

(grams/denier)

• 2.4 – 5.1

• Strength- Wet

(grams/denier)

• 2.0 – 4.3

• Extensibility • 10 - 25%

• Elasticity • 92% recovery at 2% extension

• Resiliency • Medium

• Moisture Regain @ 70F,

65% rh

• 11%

• Flammability • Burns slowly and is self-extinguishing

• Electrical Conductivity • Poor conductor; builds up static charges

• Specific Gravity • 1.25 – 1.34


– Degrades rapidly at temperatures above 350°F

– Scorches easily at temperatures above 300°F


– Good resistance to most acids except strong mineral acids

– Slightly more resistant to alkalies than wool

– Weakened by sunlight

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Mineral fibres

Asbestos is the only naturally-occurring mineral fibre. It has been used in heat-resistant

material, thermal insulation, brake blocks and reinforcement in sheet materials for building.

The use of asbestos is now rapidly declining following the discovery of health risks from

asbestos dust.

Man-made fibres

Regenerated fibres

Regenerated fibres are manufactured from a natural polymer, cellulose, which is obtained

from wood. Cellulose is also the starting product for the manufacture of paper. The

cellulose is reacted chemically so that it will dissolve in sodium hydroxide solution, then

reformed by extruding the viscose solution called viscose into dilute sulphuric acid solution.

The viscose fibres are chemically similar to cotton and share the desirable property of

moisture absorbency.

By adapting the basic production process, a range of viscose fibres with different

characteristics, including high tenacity, high wet modulus, crimped and inflated fibres, can

be produced for different uses. At one time, viscose continuous filament for tyre cord and

for textile applications was produced but this has declined and now staple fibre and tow are

mainly produced.

The viscose process is long and complicated and the by-products give rise to environmental

problems. There is much interest at present in producing man-made cellulosic fibres by an

alternative process using a solvent for the cellulose.

• Composition

– Regenerated cellulose

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Length Filament and staple

Color Transparent unless dulled by pigments

Luster Bright to dull

Strength- Dry

(grams/denier)

Regular rayon: 2.4 - 3.0; high wet modulus: 4.0 - 5.0

Strength- Wet

(grams/denier)

Regular rayon: 1.1 - 1.5; high wet modulus: 2.2 - 3.0


Elasticity 82% recovery at 2% extension (95% for HWM)

Resiliency Low

Moisture Regain @ 70F,

65% rh

11 – 16%

Flammability Burns rapidly unless treated

Electrical Conductivity Does not build up static charges



– Loses strength above 300°F

– Decomposes above 350°F


– Easily damaged by strong acids

– Resistant to most alkalies; loses strength in strong alkalies

– Lengthy exposure to sunlight weakens the fabric

– Greater affinity for dyes than cotton

Modified regenerated Fibres

These fibres include cellulose diacetate and triacetate. The raw material is again cellulose,

but in these fibres it is modified chemically so that the polymer can be dissolved in an

organic solvent. The polymer solution can then be extruded into hot air which evaporates

the solvent leaving the fibres. The polymer remains in the chemically modified form and is

not converted back into cellulose.

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Cellulose acetate fibres are produced almost entirely as continuous filament yarns and are

used in soft silk-like dress fabrics. Most cigarette filter tips are made from cellulose

diacetate fibres.

• Composition

– Acetate ester of cellulose





Strength- Dry

(grams/denier)

1.2 – 1.4

Strength- Wet

(grams/denier)

0.9 – 1.0


Elasticity 48 – 75% recovery at 4% extension

Resiliency Low

Moisture Regain @

70F, 65% rh

6.5%

Flammability Burns easily and rapidly when exposed to flame

Electrical

Conductivity

Low; static charges can develop under dry conditions



– Acetate softens and begins to melt at 347°F

– Triacetate softens and begins to melt at 455°F


– Poor resistance to concentrated acids

– Poor resistance to concentrated alkalies

– Acetate susceptible to damage by long exposure to sunlight; triacetate has

better

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Synthetic Fibres

This group includes three major classes and several minor ones. The term synthetic means

that the polymer is entirely man made.

The first synthetic fibre was a polyamide (nylon). The first polyamides were produced in

the United states in 1938 and were used initially for stockings. The application rapidly

expanded into parachute fabrics and later to many other textile products including shirts,

bedsheets, underwear, carpets and reinforcement of rubber in tyres and belts. In the last few

years, polyamides have been displaced in some uses such as shirts, bedding and underwear

by polyester/cotton blends. The properties of polyamides, particularly the excellent

elasticity, make them very suitable for carpet piles, rubber reinforcement and tights and

stocking.

• Composition of Nylon

– Nylon 6,6: polyhexamethylene adipamide; Nylon 6: polycaprolactam





Strength- Dry (grams/denier) 3.5 - 9.0

Strength- Wet (grams/denier) 3.2 - 8.0



Resiliency Good

Moisture Regain @ 70F, 65% rh 2.8 – 5.0%

Flammability Shrinks from flame and melts

Electrical Conductivity Low; can build up static charges



– Nylon 6,6 softens at 445°F and melts at 480 - 500°F

– Nylon 6 melts at 419 - 430°F

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– Dissolves in mineral and formic acids

– Good resistance to alkalies

– Loses strength under prolonged exposure to sunlight; bright yarn more

resistant than dull yarn

Polyester was first produced commercially in 1953 and having expanded rapidly, is now the

largest man-made fibre in terms of volume of production. Polyester staple fibre is very

commonly used blended with cotton or other cellulosics in shirts, blouses, dresses, trousers

and sheeting. Blends of polyester with wool are used in suitings and trousers. Polyester

continuous yarn is often used for seat belts, sewing threads and yacht sails, as well as

apparel items such as blouses. An interesting development is polyester microfibres,

extremely fine filaments, which give fabrics a soft silky handle.

• Composition of Polyester

– Combination of terephthalic acid or dimethyl terephthalate and ethylene

glycol



Color Transparent or white


Strength- Dry (grams/denier) 2.8 - 6.3

Strength- Wet (grams/denier) 2.8 - 6.3


Elasticity 97 - 100% recovery at 2% extension

Resiliency Excellent

Moisture Regain @ 70F, 65% rh 0.4%

Flammability Shrinks from flame and melts

Electrical Conductivity Low; can build up static charges



– Softens or sticks at 440 - 465°F

– Melts at 478 - 495°F

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– Good resistance to most acids

– Good resistance to most alkalies

– Good resistance to sunlight

Acrylic fibres were first produced in 1948. The fibres have a soft, warm handle and are well

suited to the production of high-bulk yarns. These find many applications in Knitwear,

carpets and pile fabrics. A variant of acrylics called modacrylic has greatly reduced

flammability and is used for children’s nightwear as well as upholstery fabrics for aircraft,

trains and public rooms.

• Composition of Acrylic

– Polyacrylonitrile and small amounts of other monomers


Length Primarily cut into staple fibers

Color White to cream


Strength- Dry (grams/denier) 2.0 – 2.7

Strength- Wet (grams/denier) 1.6 – 2.2



Resiliency Good

Moisture Regain @ 70F, 65%

rh

1.0 - 1.5%

Flammability Burns with yellow flames

Electrical Conductivity Static electricity can build up at low humidity



– Does not melt

– Sticks at 450°F


– Resistant to most acids; strong, concentrated acids can cause strength loss

– Damaged by concentrated alkalies

– Excellent resistance to ultraviolet light

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The polyolefin fibres, polythene and polypropylene, are of increasing importance and their

production now totals about 8% of all synthetic fibres. Polypropylene in particular is used

for carpets, upholstery fabrics, geotextiles (fabrics for ground and soil reinforcement) and is

now becoming more widely used for clothing. The textile uses of polythene are limited due

to the low melting point (120°C).

The other synthetic fibres are produced on a much smaller scale. The polyvinyl fibres are

mainly polyvinyl chloride or polyvinyl alcohol. The polyvinyl chloride fibres are used in

thermal wear but do not have a wide range of applications.

Elastane fibres can be extended from three to five times their original length before they

break. Small proportions are used where fabrics with stretch properties are needed.

Elastane fibres are found in swimwear, stretch trousers and lingerie.

The aramides are the newest class of fibres. Chemically, they are modified polyamides.

One type of aramide fibre has exceptionally high tenacity, up to three times that of other

fibres. The other type has excellent resistance to heat and flame although normal tensile

properties. The best known brand names and Kevlar for the first type and Nomex for the

second; both are products of the DuPont Company of the USA.

Mineral fibres

These fibres are glass, steel and carbon, all of which are found in industrial end-uses. Glass

is used for low-cost reinforced plastics for ships, car and vehicle parts and many other

applications such as thermal and electrical insulation products. Steel fibres are used for

reinforcing rubber in tyres and belts and for filters where chemical resistance is important.

Carbon fibres are manufactured from acrylic fibres and are also used for reinforcement of

plastics. Carbon fibres are very expensive and consequently go into high-cost, high-

performance reinforced plastics such as aircraft parts and some leisure goods like squash and

tennis rackets, where the user is prepared to pay for the superior performance.

Fibre Blends

For some products the ideal set of properties will not be obtainable from just one generic

type of fibre. Instead, a blend of two or more fibres will be used.

Uniform mixing of different types of fibres before spinning is known as blending of fibres

and the composite yarn thus produced is known as blended yarn.

There are number of reasons for blending fibres;

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- to produce a better balance of technical properties for a particular textile product

- to produce a cheaper product by blending a low cost fibre with a more expensive one

- to produce special colour effects by blending fibres with different dyeing

characteristic

However, there are costs as well as benefits in blending fibres. It adds an extra process to

the many involved in manufacturing. Blending is also a process that has to be carefully

controlled to avoid variability in the product. The wet processing sequence has to be

selected to avoid chemical conditions that will damage either fibre. Dyeing may well have

to be carried out in two stages, one to colour each fibre.

The most common blend is polyester/cotton, usually in the proportions 50/50 or 67/33

although other proportions are now used in some products. Blends with more than 50

percent cotton are often termed ‘cotton rich’. These blends combine the softness and

moisture absorption of cotton with the dimensional stability, hard-wearing and easy-care

qualities of polyester. The convoluted shape of the cotton fibres gives products greater bulk

and cover compared with 100 percent polyester. Fabrics are still rather lean compared with

100 percent cotton, however, the effects of burning are not entirely beneficial though.

Cotton burns readily while polyester tends to melt back from a flame and consequently does

not burn. In polyester/cotton blends, the cotton prevents the polyester from shrinking away

from a flame and the mixture burns very fiercely.

Polyester/cotton blends have given rise to new printing and other processes to produce novel

effects. Thus when a fabric made from polyester/cotton blended fibre yarn (both warp and

weft), is passed through 70% sulphuric acid, the entire cotton component of the whole fabric

is destroyed and removed, thereby keeping the polyester fibre intact. 100% terrene saries

are made by this process. In another process a thickened solution of alum is printed on the

blended fibres fabric and heated to a temperature (140-150°C) when sulphuric acid released

from the alum destroys the cotton component of the blend present at the printed portions.

This produces a transparent design on an opaque background.

Count

Yarns are described as fine, medium and coarse. This is not a clear-cut classification since

the same yarn, called coarse by the manufacturer of thin, combed yarn may be classed as

fine yarn by the blanket manufacturer. Instead of this another system in which length of yarn

per unit weight is taken as the unit. Thus in the case of cotton yarn, the count system is used.

The count of a yarn is defined as the number of hanks to a pound, each hank containing 840

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yards of the yarn. For example, if 40 hanks, each containing 840 yards of the yarn, weigh 1

lb, than the yarn count is 40 and is expressed as “40s count”.

As the count of the yarn increases, the fineness increases (i.e. the diameter of the yarn

decreases). Conversely, as the count decreases, the fineness decreases i.e. the yarn becomes

coarser (thicker). Cotton yarn is generally made in the range between 20s and 80s.

Denier

In the case of man-made fibers, the diameter of the filament yarns ( or fineness of the yarns)

is generally expressed in Deniers, which was originally developed in France for expressing

the fineness of silk filaments. In this case, if 9000 meter of a particular yarn weigh x g, then

its denier is x. In other words, denier of a yarn is the weight in grams of 9000 meters of the

yarn.

As the denier increases, the yarn becomes thicker (or coarser) and conversely, as the denier

decreases, the yarn becomes thinner (or finer).

Fibre Usage

The selection of a fibre for a particular end-product involves choice from each natural and

man-made generic type. Within each fibre generic type there will also be a range of

different fibres available. For the natural fibres, these can include varieties with different

fibres available. For the natural fibres, these can include varieties with different staple

length and linear density. Man-made fibres are also available in different staple lengths and

linear densities: they are produced as both continuous filaments and staple usually. Most

fibre types are also available in a whole spectrum of other modifications to give specific

properties, for instance differing luster, varying tensile properties, anti-static, anti-soiling,

dye variation etc.

The type of fibre chosen for a particular end-product will be determined by the best balance

of the following major quantifiable properties: tensile properties including tenacity,

extension at break, modulus and elasticity; moisture absorbency; optical character including

light reflectance and fibre shape; chemical resistance to damaging environments likely to be

found in the application; and electrical and thermal character, including ability of the fibre to

dissipate a static charge or to give a fabric the required warmth or coolness.

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Not all of the above characteristics depend solely on the fibre. The appearance of a product

will be influenced by whether it is made from staple fibre or continuous filament yarns. If

continuous filament yarns are used then the appearance will depend on whether they are

textured. Similarly, the warmth of a fabric will depend on the construction of the yarns and

the fabric as well as the characteristics of the fibre.

The consumer will also have a set of requirements from textile products and may well use

different terms. Typical terms used by the consumer are hard-wearing, easy care, comfort,

appearance, value for money and safety of the product. These attributes can not be

objectively measured, but each depends on a number of textile properties which can be

measured (Refer Table B)

Easy care means that a textile product can be washed by machine and that, after drying, the

article will be wearable without pressing.

Certain fibre generic types may be recognized as having well-defined advantages. Cotton is

known for its comfort (moisture and thermal character) and pleasing appearance (low luster

and surface irregularity); wool is considered comfortable (warmth due to the natural crimp);

regenerated cellulose -viscose- has advantages of low cost and comfort (high moisture

absorbency); synthetic fibres such as polyester, polyamide, acrylics and polypropylene have

a relatively low cost, durability (strength and toughness) and easy-care properties (low

moisture absorbency and thermoplasticity).

The ultimate marketability of a textile product depends on a balance of the above subjective

properties and on the cost.

Table B: Testing of Textile Properties

Customer term Textile property Test for property

Comfort Moisture character, flexibility,

elasticity, thermal character

Absorbency/transport

softness/resilience

Appearance Optical character, elasticity Appearance, luster, crease

resistance, shape retention

Durability Tensile strength, toughness,

flexibility, elasticity

Abrasion resistance

Easy care Moisture character, elasticity,

dimensional stability

Low absorbency

Thermoplasticity

Safety Flammability, chemical resistance LOI

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Documents

1. Fibre Introduction