Properties of cotton

Properties of cotton mean mainly physical and chemical properties. These are here:

Physical properties of cotton:

Length: 0.5-2.5 inch or 0.3-6 cm.

Diameter: 16-20microns.

Cross section: Kidney shape.

Color: White, grey, cream.

Luster: High.

Dimensional stability: Good.

Tenacity (gm/den): In dry state 3.0-5.0, In wet state 3.6-6.0

Elasticity: 74% recovery at 2% deformation and 45% at 5% deformation.

Elongation at break: 3.0-7.0%

Co-efficient of friction: 0.25.

Drapability: Good.

Resiliency: Low.

Moisture regain: 8.5% and raised to around 25-30% at 100% Relative humidity.

Specific gravity: 1.54

Chemical properties of cotton:

Effects of Acid and Alkalis: Concentrated acid or hot but low concentrated acid damages cotton. Cotton dissolved in high concentrated mineral acids such as HCl, H₂SO₄ but high resistant to alkalis. That’s why NaOH, Na₂CO₃ are used for scouring of cotton. Concentrated NaOH is also used for cotton mercerizing.

Effects of Bleaches: Resistance to bleach, but H₂O₂, NaOCl, NaOCl₂, Ca(OCl)Cl are used as bleaching agents for cotton processing.

Effect of heat: Cotton has an excellent resistance to degradation by heat. It begins to turn yellow after several hours at 120⁰C and decomposes at 150⁰C as a result of oxidation. It damaged at 240⁰C, flame at 390⁰C and burns in air and smell is like paper burning.

Effect of organic solvents: Have resistant ability to most organic solvents such as dry cleaning agents. A little organic solvents can damage cotton.

Dyeability: Have affinity to Direct, Reactive, Sulphur, Vat dye, Mordant, Indigo and natural colorant.

Effect of sunlight: There is a gradual loss of strength when cotton is expressed to sunlight and the fibre turns yellow. Ultraviolet ray is harmful for cotton.

Effect of weather: Acidic air spoils the strength of cotton. If cotton isstored carefully on dry condition it lasts for many years.

Effect of insects: Cotton is not attacked by moth grubs or beetles.

Micro-organism: Cotton is attacked by fungi and bacteria.