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 experimental data obtained for draw ratio, stress, refractive indices and birefringence were used to calculate structural parameters, such as cohesive energy density, average work per chain W′, work per unit volume W, reduction in entropy due to the elongation, work stored in the body as strain energy W″ and other parameters. Calculation of the segment anisotropy γs, the number 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 Δn, W′, N, Y and γs with the draw ratios. The study shows that new orientations occurred due to cold drawing at different draw ratios and stresses.