Long range and short range stresses in the macrodeformation of glassy polymers

Abstract The yield stresses of polyvinyl chloride, polystyrene and polypropylene in the glassy state were determined over a wide range of temperature. Stress relaxation tests showed that the stress was composed of a recoverable thermally activated component and an athermal component. The athermal stress was found to depend on the structure and was caused by long range deformation obstacles which respond anelastically. It was not possible to correlate the thermally activated stress with anelastic characteristics. Stress activation volumes were measured and related to the total and thermally activated stress.