Determination of kinetic parameters for the thermal decomposition of phenolic ablative materials by a multiple heating rate method

Abstract

The rate of decomposition for two widely used glass- and asbestos-phenolic ablative materials were measured using standard thermogravimetric techniques. Thermograms were obtained at six heating rates ranging from 10°C min −1 to 160°C min −1. From these data the kinetic parameters were determined by a slightly modified version of Friedman's method. Fractional weight loss calculated using the derived kinetic parameters over the temperature range of decomposition agreed with measured values with a mean error of 0.33 and 0.28%, with a standard deviation of errors 0.58 and 0.84% for glass- and asbestos-phenolic, respectively. The 95% confidence for the mean error was 0.22 and 0.44% for the glass-phenolic and 0.14 and 0.42% for the asbestos-phenolic. Also, the activation energy was calculated by the method of Flynn and Wall. The average activation energy values determined by the two methods agreed within 4.6% for both materials.