TECHNOLOGICAL EVALUATION OF NITROGEN-CONTAINING STARCH DERIVATIVES ASSIZING AGENTS

The structural changes brought about by introducing different nitrogen containing groups via cyanoethylation, carbamoylethylation and carbam ation in the molecules of rice and maize starches and oxidized starche s derived thereof and the onset of these changes on the technical prop erties of yarns sized with such starch products were investigated. It was found that the apparent viscosity of pastes prepared from those pr oducts depends on the nature of starch, the degree of oxidation prior to chemical modification, the nature of modification as well as the me asuring conditions, i.e. the rate of shear and temperature. Cotton yar ns sized using these starch derivatives were measured for yarn number, tensile strength, C.V.%, elongation at break and C.V.% in elongation. Besides, the weavability test expressed as the minimum number of cycl es due to abrasion (St1) and average number of cycles due to abrasion (St6) were investigated. A comparison among modified starches prepared from rice starch would reveal that the highest value of St1 is obtain ed with yarns sized using carbamoylethylated sample derived from unoxi dized starch. With maize starch, on the other hand, the highest value of St1 is obtained with cotton yarns sized using carbamoylethylated st arch derived from starch oxidized by 1 g/l active chlorine.