Natural Fibre - Cotton

Introduction

• Cotton is a natural vegetable

fibre produced in the cotton

plant in many countries of the

world

• Cotton is widely used Textile

Fiber in Textile Industry, due

to it’s versatile uses.

What is Cotton?

• Cotton is a fibre that grows from thesurface of seeds on the pods or bolls. It iscomposed basically of a woody substancecalled “Cellulose”.

Types of Cotton

1. Sea Island CottonThis is of the highest quality and the most valuable of commercial cottons. Itgrows on the coast of the Gulf of Florida in Barbados and in other adjacentislands where the climate is favorable.

2. Egyptian CottonThere are two kinds of Egyptian cotton, brown and the other white. It is likeSea Island cotton, very regular and contains few immature and dead fibres.

3. American CottonThis is cultivated in the United States, and is the most abundant type ofcotton.

4. Indian CottonIt is a short fibre of between 0.6 and 0.8 inch length. It is therefore onlysuitable for spinning coarse count.

4. China CottonThis is about the lowest commercially acceptable grade. Its twist is nothighly developed and it is rather harsh. It does not spin a good yarn alone,and is usually used in a mixture with better qualities.

Cotton Polymer System

• Cotton polymer is a liner, cellulose polymer.• The repeating unit is cellobiose which consists of two glucose unit.• Cotton consists of 5000 cellobiose units therefore degree of

polymerization is 5000. polymer length is about 5000nm andthickness is 0.8 nm.

• Cotton is a semi-crystalline fibre; crystalline regions are 65-70 %while amorphous regions are 30-35 %.

• Hydrogen bonding are the dominant and most important forces ofattraction between polymeric chains. –OH,-CH2OH give rise to hydrogen bonds.

• The polymeric system can be imagined as roll of wire netting.

Cotton Fibre Morphology

Macro structure• Cotton appear as fine, regular fibre with little variation in diameter;

its diameter is not considered as critical as length. The fibre lengthto breath ratio is 6000:1 for finer and long cotton and 350:1 forshortest and coarser cotton type.

• Its length is from 10mm-65mm.• Range in fibre diameter is from 11µm 10 22 µm.• Cotton color varies form near white to light tan. The colour depends

upon cotton type, soil, environmental and climatic conditions underwhich it is grown.

• Under microscope cotton looks like ribbon or twisted tube. Thesetwists or convolutions classified cotton under the microscope.

• Convolutions are formed after the cotton ball burst open.• Cotton cross-section appears under the microscope as kidney

shape.

Characteristics of Cotton

Advantages• Cotton can be processed into a wide selection of fabrics. Among

the sheer fabrics are cambric, batiste, chiffon, lawn, organdy andvoile. Medium weight cottons include broadcloth, drill, flannel,poplin, terrycloth and long cloth. The heavy weight cottons includebrocade, corduroy, denim, pique and velveteen.

• Cotton can be mercerized to improve luster, absorbency, dye-ability and strength.

• Textured effects are easily achieved either by yarn structure (hightwist yarns, nub yarns, boucle yarns, and crimped yarns), fabricconstruction (crepes, seersuckers) or application of specialfinishes (embossing, napping).

• Cotton fabrics can be easily dyed or printed with almost all theclasses of dyes. Pigment printing can be done with the help of abinder.

• Cotton is absorbent, does not build up static electricity and is agood conductor of heat and hence is very comfortable to wear.

Characteristics of Cotton

Disadvantages• Untreated cotton wrinkles easily.• Cotton is susceptible to mildew if left

damp.• Cotton is flammable.• Fabrics take a long time to dry.

Various Finishes of Cotton

• Mercerization- adds strength, improves lustre,absorbency, dyeability

• Sanforization-ensures less than 1 % shrinkage• Moireing- for variable luster and variable pattern• Glazing-gloss, smoothness and embossed

effects• Stiffening- smoothen, stiffens and strengthens• Wrinkle resistant permanent press- improves

shape-retension and imparts dip-drycharacteristic

• Schreinerizing-adds luster

Various Finishes of Cotton

• Stain repelling-for easy care• Napping-for softness, warmth and increased

absorbency• Singeing-for smoothness• Weighting-for bulk• Insulating-for warmth• Embossing-for decoration• Mildew resistant• Fire-retardant• Moth-resistant