Cotton Fibres

COTTON

Introduction

Most of the people wear cotton fabric. People like cotton fabrics more than any other fabric. Cotton (Figure 2.5) was being used even before 3000 BC. Cotton fabrics are both soft and strong. Cotton is most popular and widely used fabric. Heavy weight cotton fabrics are even used as roofing of houses, making footwear and bags.

Growth and Production

Different types of cotton fibres can be produced from the same cultivation area. It takes 200 – 220 days for the cotton plant to grow fully. Sunlight and humidity are needed for the growth of cotton. Some varieties of cotton need 3-5 millimeter of rain for its growth. The quality of cotton depends upon the soil type, atmospheric condition and fertilizers used. In South India, cotton is sown during the month of September and October whereas during the same period it is harvested in North India. Therefore, India cultivates cotton throughout the year.

Cotton Cultivation and Harvesting

Soil

For cultivation of cotton clay, sand and red sand are highly adapted.

Climate

The climatic condition needed for the growth of cotton is warmth and moisture content in air. There should be continu-ous rain during sowing of cotton; this will help for the fast growth of the plant. Apart from this a good sunlight, moderate warm temperature is also needed throughout the growth period.

The Time of Sowing

It can be sown from April to August. The duration for full growth is 120-180 days.

The Method of Sowing

At first, the land is ploughed well, so that the air moves freely within the soil. The seed is sown between 1- 15 meter gaps each. The seeds will start germina-tion within 10-14 days. Later, the growth will be much quicker. The strong plants are selected and replanted with equal space. The flowers start appearing within 2-3 months. Later, the fruit starts to grow with a green colour seed. The cotton seeds will be present inside the fruit. In these seeds the cotton fibres will start growing from outside. Later, the fully grown cot-ton fruit (Figure 2.6) will blast and the cotton fibres will come out.

Harvesting

The cotton fibre should be collected at once; otherwise the cotton fibre with seed will be carried away by wind. Dust particles will also spread over cotton fibre, resulting in colour change of the fibres. Harvesting can be done by hand or by using machines. Next, the harvested cotton fibres are sent to ginning mills (Figure 2.7).

Ginning

The harvested seeds are dried using warm air, and stored for ginning. Ginning is the process of separation of fibres from seeds. Later using special machines the fibres are separated from the seeds. The sepa-rated fibres are called lint, which have a staple length of 15 to 50 mm. The very short fibres are called linters. Hundred kilogram of clean cotton seeds yield 35 kg of fibres, 62 kg of seeds and 3 kg of waste. The lint’s are compressed into bundles of 500 kg and sent to spinning mills for yarn production.

Characteristics of Cotton

Luster : Low

Tenacity / Strength : Medium

Elastic Recovery : Low

Elongation : 7%

Resiliency : Low

Density : 1.54 g / cm3

Moisture Absorption : 8.5%

Dimensional Stability : Good

Reaction with Acid : Weakens fibres

Reaction with Alkalies : Resistant (Mercerization)

Effect of Sunlight : Weakens fibres slowly

Insects : Silverfish damages the fibre

Reaction to Flame : Burns readily

Shape : Straw like Structure

Width : 12 – 29 mm

Length : 1.25 – 6 cm

Colour : White, Cream White

Drying : Quick and Good

Dyeing : Good Absorption

Common Uses of Cotton

·           Clothing (Frocks, Socks, Towels, Saree, Dress Materials).

·           Household Textiles (Bed Spread, Pillows).

·           Medical Textiles (Absorbance Pads, Bandages).