Influence of temperature on the optical and structural properties along the diameter of: I. Polymer fibres

A modified heating device connected to a wedge interferometer is designed t o study the influence of temperature on the optical and structural properti es along the diameter of undrawn polypropylene fibres. To determine the opt ical orientation function profile, a model that divides the circular cross section into very small circular zones is suggested. The refractive indices and optical orientation function of each zone are considered assuming ther e is a constant fully oriented birefringence throughout the fibre. This inv estigation provides useful information about the structural properties of p olypropylene fibres and throws light on its opto-thermal behaviour. The inv estigation is carried out using multiple-beam interference Fizeau fringes i n transmission. Microinterferograms are given for illustration.