Chemical properties of textile fibres

Acid and Alkali

Acid or alkali is harmful for cellulose and protein fibres. Therefore, the effect of acid and alkali must be known during bleaching, dyeing and finishing. Different fibres react differently with acid and alkali. For example, Cotton and Lilen damaged when they are subjected to conc. Hydrochloric, Sulphuric and Nitric acids. Also dilute solution of those acids can make harm to the fibres. On the otherhand, conc. alkaline solution is not harmful to Cotton and Lilen. Wool is not effected by dilute solution of acid. But conc. acid and alkali damage wool easily. So acid or alkali must bechosen properly to use in different purpose and processing.

Water

Water is very important to determine the properties of fibres. According to the behaviour of fibres with water, fibres are classified into two groups – hydrophobic and hydrophilic. Water is used in process like scouring, dyeing etc.

Moisture Regain

Moisture regain is expressed as percentage. It is the ratio of oven dry weight of a material to the weight of water in this material and multiple of hundred.

Moisture Content

Moisture content is also expressed as percentage. It the ratio of oven dry weight of a material to the total weight(oven dry weight + weight of water in this material) of the material.

Absorbency

Normally, textile fibres absorb moisture. The ability of fibre to take up the moisture is known as absorbesncy. The absorbency is expressed in the terms of moisture regain. Among the all fibres cotton absorbs easily. For the property cotton requires more time to dry. Moisture regain of wool is 16%. It is 10% for silk. but it seems like dry after regain for silk. The cloth we wear are more comfortable which ability is higher to absorb.

Heat

Effect of heat si a vital point during dyeing, ironing, steaming and some other operations. Different fibres behave differently under heat. Some fibres burn where some scorch when heat is applied. Some fibres are not combustible e.g. mineral fibre, glass fibre etc. Cotton is easily flammable, wool is hardly flammable fibre.

Sunlight

When we wear cloth or fabric it comes into the touch of sunlight. It is very familier to us. Effect of sunlight should be kept in mind for general people. Sunlight reduces the strength of cotton and it becomes yellow. Lilen is better than cotton in sunlight. But cotton is better than silk.

Biological agent

If the fibres are attacked by bacteria’s, black spots are seen on the fibres as a result of which the strength of fibre is reduced. Its importance whether fibers attached by micro-organisms or not upon which strength of products depends. Cotton, Lilen and rayon attacked by fungus. Silk, wool, acetate, tri-acetate and spandex have better resistance to mildew and other insects.