A general model for the temperature-dependent deformation and tensile failure of photo-cured polymers

The nonlinear finite deformations and ultimate failure modes of photo-cured polymers are closely related to the ambient temperatures, typically exhibiting enhanced stretchability and a peak of ultimate break strain near the glass transition temperature T_g. The origin of this type of temperature-dependent failure phenomenon lies in the evolution of visco-elasto-plastic flowing dynamics as well as the alteration of polymer chain mobility during glass transition. In the past few decades, theoretical models for the strength of polymers were developed independent of the visco-elasto-plastic deformation history and the glass transition dynamics. These models could not provide reasonable explanations for the peak of ultimate break strain in photo-cured polymers, nor predict the poor stretchability at ultra-low and ultra-high temperatures. In this paper, we propose a general model for the temperature-dependent deformation and tensile failure of photo-cured polymers, in which the breaking phenomenon is dominated by a competition between the brittle failure at low temperature, the visco-plastic failure at moderate temperature and the hyperelastic failure at high temperature. Through the comparison between theoretical predictions and typical experiments, the model is proved to be efficient in predicting the deformation and failure of both photo-cured thermosets and thermoplastics.