Interferometric measurement of some structural parameters of drawn polyethylene fibres

Abstract

Multiple-beam interference Fizeau fringes are used to determine the optical orientation function and molecular structure of drawn polyethylene fibres. The optical orientation function across the fibre radius is obtained at a certain draw ratio, and the measurements of at different draw ratios can be used to give useful information about the fibre structure. Empirical formulae are suggested to correlate the birefringence with the refractive indices and with the draw ratio. Some parameters dependent on the fibre structures are also determined. Illustrations are made using microinterferograms.