Comparative study of degumming of silk varieties by different techniques

Abstract

Different varieties of silk differ from each other in their chemical composition as well as the physical, chemical and mechanical properties. Silk degumming is a primary important process, which needs to be carried out uniformly to a sufficient level to get good quality in further processes such as dyeing. In the present study, we have compared the efficiencies of five different degumming treatments for eri, tasar and mulberry silk fabrics using conventional, ultrasonic and microwave techniques. Among the various treatments, soda ash plus hydrogen peroxide and enzyme (papain) degumming recipies gave the best results in terms of weight loss and absorbency. As compared to the conventional technique, the treatments under ultrasonication and microwave enhanced the efficiency. The microwave technique was found to be superior, with the advantage of drastic reduction in treatment time, better retention of tensile strength and smooth appearance of silk. The dye uptake also increased after degumming. The molecular conformation of the different silk varieties, as estimated by FTIR spectroscopy, and the crystalline structure, as elucidated by X-ray diffraction, remained unchanged. SEM showed distinct morphological changes on degumming.