Effects of porosity on the cure kinetics and residual stress of a porous polymer

Porosity is a concern to polymer composites, however, prior to reinforcement, the porosity is found to affect the cure performance of the base polymer. In this study, a multi-scale predictive tool is developed to estimate this effect of porosity on curing and post-cure of a thermoset porous polymer. The model is created in Abaqus with the help of a user defined dynamic RVE. The novelty includes a user constitutive model and effects of random distribution of pores in the dynamic RVE on the cure kinetics of the polymer. It is found that the cure rate varies with the degree of cure and the direction of heat flow across the control domain. At a degree of cure of magnitude of 0.7, the cure rate is found to be 1.35 and 1.5 times in the middle and the bottom of the domain with respect to the cure rate at the thermal boundary surface. The residual stress is found to drop by 3% and 7% at a porosity of 3% and 5%. The model is capable to incorporate reinforcements and predict the cure performance at the porous fibre-polymer interface.