Effect of strain rate and temperature on tensile properties of ethylene-propylene block copolymers

摘要

Tensile tests were conducted on several ethylene-propylene block copolymers with different ethylene content, over a range of temperatures (-120 to 23 ℃) and strain rates, 10~(-4)-10~(-2)s~(-1). The effect of temperature and strain rate on elastic modulus, Poisson's ratio and yield stress has been analyzed. To determine the elastic properties, a video-extensometer was used to determine the deformation field. The experimental results about yielding are interpreted in terms of the well known principle of temperature-time equivalence. Several models have been considered to explain the significant increase in the yield stress at low temperatures or high strain rates.