Anisotropic Optical Properties of Nylon 6-6 Fibres as a Function of Annealing and Quenching Processes

Abstract

Changes in the structure of nylon 6-6 fibres after annealing and quenching in coarse grained ice at 160°C were studied interferometrically. The Pluta polarising interference microscope has been used to determine the mean refractive indices and mean birefringence of these fibres. The optical orientation function and the molecular structure of the annealed and quenched nylon 6-6 fibres were calculated. The density and the mechanical loss factor of the annealed and quenched fibres were measured by a system based on vibrating strings. The density results were used to calculate the degree of crystallinity. Relationships between the mean refractive indices, birefringence, isotropic refractive index and polarisabilities per unit volume at various times are given for these fibres. The behaviour of fibre density and the mechanical loss factor under different annealing and quenching conditions were discussed with different optical parameters. The results obtained clarify the effect of annealing and quenching conditions on the orientation function, orientation angle and other optical and mechanical parameters. The effect of the annealing conditions on the refractive index profile was studied. Illustrations are given using graphs and microinterferograms.