Thermogravimetric analysis (TGA) was used for the observation of the pyrolysis kinetics characteristics of high density polyethylene (HDPE)-based composites enhanced by a variety of basalt fibers (BFs) and wood flour (WF). The improved Coats-Redfern (C-R), Flynn-Wall-Ozawa (F-W-O), Friedman, and Kissinger methods were utilized to ascertain the specific apparent activation energy (Ea) of each component and composite material. The results indicate that BFs do not decompose under 800 °C, while the pyrolysis of WF and waste HDPE showed two significant weight loss zones (250-380 °C and 430-530 °C), relative to cellulose/hemicellulose and HDPE thermal degradation, respectively. The average Ea of WF/BF/HDPE composites over the entire pyrolysis process obtained by the modified C-R method fluctuated in a range of 145-204 kJ/mol and increased with the BF content, which was higher than that of WPC (115-171 kJ/mol). The value of Ea computed by the F-W-O method was significantly lower than that computed with the improved C-R method, which could validate the reliability of two methods by comparing with the literature. The Friedman and Kissinger methods were not applicable to this composite material reinforced by mixed fillers, so the obtained Ea values were quite different from the previous two methods. The changes in Ea showed that the addition of BFs could improve the average Ea and further enhance the thermal stability and flame resistance of the composites.
Keywords: TGA; apparent activation energy; basalt fiber; kinetics; thermal decomposition.