Analytical Investigation of the Thermal Response of Decomposing Polymer Composites

A numerical study of the thermally induced response of two widely used glass-filled polymer composites has been performed. This study was conducted using a newly developed mathematical model, which, unlike previous models, does not include the idealized assumption of local thermal equilibrium existing between the solid matrix and product gas. Experimentally determined volumetric heat transfer coefficients were used to characterize the rate of energy transfer between the two phases within the tortuous pore network of each material. These coefficients were introduced into the model in the form of a Nusselt number/Reynolds number correlation developed in this study. The results of the present investigation include solid temperature, product gas temperature, pyrolysis mass loss, pressure, gas mass flux, gas-storage ratio, and expansion and volumetric heat-transfer coefficient profiles. Material composition and processing were used to compare and contrast these results. Of particular interest, the deviation from thermal equilibrium in one material has been predicted to be as high as 500 degrees C. A general discussion on the effect of the assumption of local thermal equilibrium is presented based on preliminary findings.