Investigation of the thermostability of poly(ethylene terephthalate)-hemp fiber composites: Extending natural fiber reinforcements to high-melting thermoplastics

The thermal stability of poly(ethylene terephthalate) reinforced with 1, 5, 10, 15, and 20% hemp fibers was investigated with the aim of extending the applications of biocomposites to high-melting thermoplastics. The material was injection-molded following compounding with a torque-based Rheomix at 240, 250, and 260 degrees C. A combination of thermogravimetric methods at 5, 10, and 20 degrees C/min, Liu and Yu's collecting temperature method, and Friedman's kinetic method were used for testing and analysis. A significant thermostability for all formulations was observed below 300 degrees C; this demonstrated their potential for successful melt processing. Moreover, two degradation steps were observed in the temperature ranges 313-390 and 390-490 degrees C. The associated apparent activation energies within the temperature ranges were determined as 150-262 and 182-242 kJ/mol, respectively. We found that the thermostability was significantly affected by the heating rates; however, the effect of the temperature of the mixing chamber was negligible. These findings suggest that the successful melt processing of high-melting thermoplastics reinforced with natural fibers is possible with limited fiber thermodegradation. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42500.