Effects of acetylation on the thermal decomposition kinetics of makino bamboo fibers

Abstract

In this study, makino bamboo (Phyllostachys makinoi) fibers were acetylated with different solution ratios of acetic anhydride/dimethylformamide using a liquid phase reaction. This reaction resulted in the production of acetylated bamboo fibers (BFs) with the following weight percent gains (WPGs): 2, 6, 9, 13, and 19%. The effects of the acetylation level on the thermal decomposition kinetics of bamboo fibers were evaluated by thermogravimetric analysis. The results revealed that as the acetylation level increased, both the onset and maximum decomposition temperatures increased. In addition, four model-free iso-conversional methods, the Friedman method, Flynn–Wall–Ozawa method, the Starink method, and the modified Coats–Redfern method, were used to determine the thermal decomposition kinetics. Accordingly, the activation energies of thermal decomposition with conversion rates ranging between 10% and 70% were 191–196, 190–191, 192–194, 182–186, 186–191, and 189–201 kJ/mol for unmodified BFs and acetylated BFs with WPGs of 2, 6, 9, 13, and 19%, respectively. There were no significant dependencies among them. Furthermore, the Avrami method was used to determine the reaction order of unmodified BFs (0.47), which was lower than those of acetylated BFs (0.55–0.74).