CHEMICAL PROPERTIES

The giant molecular chains of textile fibres have two regions; crystalline and amorphous. Actually there is no sharp dividing line between these two regions. Tensile strength is due to crystalline regions, and its flexibility depends on amorphous areas; satisfactory textile fibres have these two regions balanced to the best advantage.

The chemical properties of textile fibre can be considered in two ways; 1^st, according to the properties of the simple units which build up the molecular chain, and 2^nd, according to the properties which hold these unite together in the chain-molecule and also the chain-molecules in bundles.

The two great classes of fibrous materials are the carbohydrates and proteins. Hence, part of chemical behaviour of the cellulose fibres is due to that of glucose unit with its alcoholic groups, and part of the behaviour of the protein fibres is due to that of amino-acid residue with its atmospheric nature. Both of these units contain hydrophilic groups, so that a strong affinity for moisture may be expected. Cellulose fibres are susceptible to those reagents which attack polysaccharides at the glycosidic linkage, and that the polypeptides are sensitive to reagents which attack the peptide linkage.