The optical behaviour of polyethylene fibres with different draw ratios

Abstract

Seven samples of polyethylene fibres with different draw ratios were studied by means of the measurement of their refractive indices and birefringence. In this study three independent techniques were used. These techniques were the Becke line, two-beam and multiple-beam Fizeau fringes. Variation of refractive index of the fibre with temperature was determined for two different draw ratios. Applications were carried out in which multiple-beam Fizeau fringes in transmission were used to determine the constants of Cauchy's dispersion formula. The resulting data were utilized to calculate the polarizability per unit volume of the fibre material. Relationships between the optical parameters and the draw ratios are given. The results obtained clarify the effect of the draw ratio on the optical behaviour of polyethylene fibres. Microinterferograms are given for illustration.