COMPLIANCES AND FAILURE MODES OF ORIENTED CHAIN-EXTENDED POLYETHYLENE

The quantitative dependence of Young's modulus and fracture behaviour on the angle between the tensile axis and the orientation direction has been determined for oriented polyethylene with lamellae of chain-extended dimensions. The form of the modulus dependence was similar to that for the majority of oriented polymers which have been studied, but the fracture behaviour was atypical, ductility only being obtained when the test axis was parallel to the orientation direction, with brittle fracture occurring in all other directions for all except very high molecular mass materials. The behaviour of this material in compression along c has also been studied; in this case kink bands and c-axis cleavage were observed. It is shown that kink band formation may be explained solely by uniform c axis shear deformation of the lamellar crystals. © 1979 Chapman and Hall Ltd.