Cotton Fibre widely used natural firbe which is constist of 85.5% cellulose. That’s why It’s also called cellulosic firbe. Cotton is the most important natural fibre and it accounts for about 50% of the total fibre production of the world. Cotton fibre is obtained from the seed of the botanical family Gossypium. It is a cellulosic fibre, which is actually the most pure natural form of cellulose.
Botanical name of cotton fibre: Cotton bears the botanical name Gossipium, a member of the Mollow family. There are 50 species of cotton plants however only four of them have attained commercial.
- Gossipium Barbedence: Sea Island cotton, Egyption cotton & American cottons are belonging to this class.
- Gossipium Harbeceum: China cotton belongs to this class.
- Gossipium Hirautum: They are mostly cultivated South & North America.
- Gossipium Paravianum: There are originally from South America But also grown in India, Pakistan & China.
Fig: Cotton Fibre
Identification of cotton fibre:
Burn test: When ignited, it does not shrink from the flame & burns with a yellow flame while in it. It continuous to burn when the flame is removed smells like burning paper. There is a little grey ash residue after extinguishing.
Chemical test: Treatment with H2SO4 : with concentrated H2SO4 (98 % cold) the cotton fibre will be destroyed that is the cellulose components will be dissolved.
The micro-structure of cotton fibre:
The cotton fibre is made up of a cuticle, primary wall, secondary wall & lumen.
Cuticle: The cuticle is a wax like film covering the outer wall.
Primary wall: The primary cell wall which is immediately underneath the cuticle is about 200 mm thinks. It is composed of fine thread of cellose called fibrils.
Secondary wall: Beneath the primary cell wall lies the secondary cell wall which form the bulks of the fibre. Its fibrils are about 10 mm thinks.
Lumen: The hollow canal, running the length of the fibre is called lumen.
The cotton polymer:
The cotton polymer is a linear, cellulose polymer. The repeating unit in the cotton polymer is cellulose which consisting of two glucose unit.
The cotton polymers consist of about 5000 cellulose unit that is its degree of polymerization is about 5000.
The most important chemical grouping on the cotton polymer are the hydroxyl groups or –OH group. These are also present as methanol groups or –CH2OH.
Crystallinity: Arrangement of polymer during crystallization may be random or parallel. Where the arrangement is random called amorphous region & is parallel called crystalline region. Many properties of fibre depend on crystallinity.
Ginning: The process of separating the seed from the cotton fibre is called ginning
Lint: Cotton fibre after separated from the seed is called lint.
Linters: The short, fuzzy fibres still attached to the seed after ginning is called linters.
Chemical varieties of cotton:
The more important varieties in order to decreasing fibre length;
- Sea Island cotton.
- Egyptian cotton.
- Upland cotton.
- Indian cotton.
Effect of –
Acid: Strong acid weaken & destroyed the fibre concentration Nitric acid for short time causes some shrinkage & increase strength & dye ability.
Alkali: The fibre show excellent resistance to alkali.
Organic solvent: Resistance so dry wash is possible.
Heat: Conductive ironing temperature 1500 C
- Decompose temperature 2400 C
- Ignition temperature 3900 C
- e.Vat – dye.
Cotton color standard:
Classification of raw cotton color;
- Light spotted
- Yellow stained
Use of Cotton Fibre:
The above end uses for affection fibre cover cutting apparel, home furnishings, and added automated uses (such as medical supplies). The affection fibre is fabricated primarily into yearns and accoutrement for use in the bolt and accoutrement sectors (wearing accoutrement would annual for about 60% of affection consumption). Affection is aswell acclimated to accomplish home furnishings, such as draperies (eventually the third above end use) or able accoutrement (about 5% of affection fibre demand).
Besides acceptable uses and as a aftereffect of altered finishing processes that accept been activated to the affection fibre, affection is fabricated into specialty abstracts acceptable for a abundant array of uses. Affection fabrics with specialty applications include, for example, fire-proof (flame resistant) apparel, which is acceptable for able uses and provides able aegis adjoin abeyant risks associated with top temperature and decidedly flashover. Blaze aggressive affection fabrics are advised with chemicals. Without actinic treatment, affection would bake up absolution actual able heat, just like the above allotment of constructed fibres, which cook if they are apparent to top temperatures.