A study of the effects of the assumption of local-thermal equilibrium on the overall thermally-induced response of a decomposing, glass-filled polymer composite

Abstract

An analytical study is conducted to determine the thermal response of a widely used ablative glass-filled polymer composite. This study is performed using a newly developed one-dimensional, transient numerical model which does not include the idealized assumption of local-thermal equilibrium existing between the solid matrix and decomposition gases within the tortuous pore network of the material. Results of this study include solid temperature, decomposition gas temperature, solid mass loss, pressure, permeability, porosity, gas mass flux, gas mass storage, expansion and volumetric heat transfer coefficient profiles. Deviations from local-thermal equilibrium as high as 200°C are predicted. Pressures as high as 10 atm are predicted, and the existence of such high pressures is verified experimentally. An investigation into the effects of the idealized assumption of local-thermal equilibrium reveals significant errors associated with the assumption.