A Coupled Thermo-chemo-mechanical Model for High Temperature Oxidations in Polymers and Polymer Composites

Abstract

High temperature oxidation in polymers is a strongly coupled, highly nonlinear and complex process which limits the use of polymeric materials in several aerospace and defense application as it causes significant performance degradation. The coupled diffusion-reaction process that occurs during thermo-oxidation together with the macromolecular network behavior and finite viscoelasticity of a polymer require a time, temperature and oxidation dependent constitutive law to predict the mechanical response of the material. In this work, a thermos-chemo-mechanically coupled constitutive model was formulated for polymer oxidation. The model was studied for regular and excess oxygen case. The material properties were studied from the preliminary work. The modulus of the oxidized material increases compared to the virgin polymer. It was also noted that in presence of external strain (deformation) the situation aggravates and accelerates the oxidation process.