Optical and structural changes in perlon fibers due to different stresses

A mechanical device has been used to measure stress as well as strain, and connected to a polarizing interference Pluta microscope to investigate the opto-mechanical behavior of trilobal nylon 6 (perlon) fibers. The experimen tal data obtained for draw ratio, stress, refractive indices and birefringe nce were used to calculate structural parameters, such as cohesive energy d ensity, average work per chain W', work per unit volume W, reduction in ent ropy due to the elongation, work stored in the body as strain energy W " an d other parameters. Calculation of the segment anisotropy gamma(s), the num ber of network chain per unit volume N and the number of crystals per unit volume Y were also given. Empirical formula was suggested to correlate the changes in Delta(n), W', N, Y and gamma(s) with the draw ratios. The study shows that new orientations occurred due to cold drawing at different draw ratios and stresses. (C) 2000 Elsevier Science Ltd. All rights reserved.