Radius of gyration, maximum extensibility and intrinsic crazing in thermoplastics

Abstract

An expression for the radius of gyration of a deformed chain is derived, assuming affine deformation of end-to-end vectors defining an entangled length, and random chain behaviour on a shorter scale. This expression is compared with small-angle neutron scattering results from the literature on variation with strain of the radius of gyration. The theoretical variation of the radius of gyration with strain is used to derive an expression for the dependence of limiting glassy-state extensibility on rubbery state pre-strain. This expression is found to give an adequate description of experimental observations of limiting extensibility identified with the critical strain for initiation of intrinsic crazing.