Effect of the Tensile Strain on the Propagation of Longitudinal Elastic Waves in the Volume of an Amorphous Polymer

The features of propagation of elastic waves in samples of polyacrylonitrile butadiene styrene, which is an amorphous polymer, have been studied at different tensile strains. Measurements are carried out both after load removal and under direct loading, which makes it possible to evaluate the acoustoelastic effect in the linear elastic deformation region. The effect of generation of local microregions with reduced elastic characteristics has been detected near the transition of the amorphous polymer into a plastic deformation region. Involving experimental data and a cluster model of the structure of amorphous polymers, a mechanism for the rearrangement of the supramolecular structure under uniaxial tension has been proposed.