Skin-core structure investigation of polyethylene fibres by multiple-beam interferometry

The authors studied macro-structure changes in drawn PE fibres interferomet rically at room temperature. The optical properties, for both the fibre ski n and core, and stress-strain characteristics produced in these fibres were measured by the application of multiple-beam Fizeau fringes using the tran smission method. The optical and mechanical results were used to calculate the orientation functions, the stress optical coefficient and the optical c onfiguration parameter. Structural parameters such as cohesive energy densi ty (CED), average work per chain W', work per unit volume W, the reduction in entropy DeltaS caused by elongation, shrinkage stress and the dielectric constant at infinity were also calculated The fibre diameter was determine d using a laser forward diffraction technique. The study shows that new ori entations as well as changes in the skin and core structure occur as a resu lt of cold drawing under stress.