Effects of Prior Aging at 316 deg C in Argon on Inelastic Deformation Behavior of PMR-15 Polymer at 316 deg C : Experiment and Modeling

The inelastic deformation behavior of PMR-15 neat resin, a high-temperature polymer, was investigated at 316 deg C. The experimental program was designed to explore the influence of strain rate on tensile loading, unloading, and strain recovery behaviors. In addition, the effect of the prior strain rate on the relaxation response of the material, as well as on the creep behavior following strain controlled loading were examined. The material exhibits positive, nonlinear strain rate sensitivity in monotonic loading and unloading. Early failures occur in the inelastic regime. The recovery of strain at zero stress and creep response are strongly affected by prior strain rate. The prior strain rate also has a profound influence on relaxation behavior. The experimental data were modeled with the Viscoplasticity Based on Overstress VBO theory. Additionally the effects of prior aging at 316 deg C in argon on the time rate-dependent behavior of the PMR-15 polymer were evaluated in a series of strain controlled experiments. Based on experimental results, it was stated that the specimens, which are subjected to prior aging in argon for more than 50 h, exhibit only quasi-linear behavior until failure.