Plasticity-controlled failure of sintered and molded polyamide 12: Influence of temperature and water absorption

The influence of stress, temperature, and relative humidity on plasticity-controlled failure of molded and laser-sintered polyamide 12 (PA12) has been investigated. Ree-Eyring's flow theory is employed and modified to take into account the effect of relative humidity on the deformation kinetics. By introducing the concept of critical strain, time to failure in plasticity-controlled regime is predicted starting from the yield kinetics. Creep test is performed to estimate the critical strain and to validate model predictions. The model predictions are in good agreement with the experimental results, showing that the model is a suitable and reliable tool to evaluate mechanical response as function of temperature and relative humidity. We demonstrate that, while, at high applied strain rates, a significant difference is found, the mechanical response under constant strain rate as well as the failure kinetics in plasticity-controlled regime of the sintered PA12 are comparable with those of the molded material. (c) 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48525.