THE CHANGES IN ELASTIC PROPERTIES OF ORIE NTED POLYETHYLENE SAMPLES UNDER LOADING

The behavior of oriented PE samples with various degrees of orientatio n was studied by measuring the rate of sound propagation C and decreme nt alpha. Change in C under loading is determined by the applied stres s sigma. The dependences C(sigma) are linear functions intersecting in a single point sigma, which is less than a certain temperature-depend ent value sigma. The position of this intersection point depends on t he degree of orientation of the sample. At sigma > sigma the dependen ce C(sigma) deviates from linear, and at T > 70-degrees-C the linear s egments of these dependences do not have a common intersection point. The relation between the changes in elastic properties of highly orien ted PE samples and the processes of deformation and creep was analyzed .