Appendix 2: Chemicals in Pre-Treatment

Information for this Appendix is provided by Dr R B Chavan


Starch is the main ingredient for sizing of cotton warp. The chemically starch is represented as:
Thus chemically starch consists of two components, a straight chain polysaccharide of glucose known as Amylose and a branched chain polysaccharide of glucose known as Amylopectin.


The straight chain component, is relatively low in molecular weight, water soluble, and makes up 20-30% of starch.


The branched chain component, is relatively high in molecular weight, water insoluble, and makes up 70-80% of starch. It is therefre the amylopectin component that is difficult to remove in Desizing.

Due to presence of high mol. Wt. cross linked Amylopectin Starch swells in boiling water but remains insoluble in water. Therefore it should be converted into water soluble form by suitable chemical reactions such as hydrolysis or oxidation. The process of removal of starch by converting it from water insoluble form to water soluble form is known as desizing.

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