Thermal decomposition kinetic of acetylated bamboo fiber and its effect on the crystallization behavior of polypropylene

• Main Authors: Yu-Shan Jhu, 朱羽珊
• Other Authors: Jyh-Horng Wu
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/86br4d

碩士 === 國立中興大學 === 森林學系所 === 106 === In this study, Phyllostachys makinoi fibers were acetylated by different content of acetic anhydride/dimethyl formamide, and thus received acetylated bamboo fibers with various weight percent gains (WPGs) of 2, 6, 9, 13, and 19%. The effects of unmodified and acetylated bamboo fibers on thermal decomposition were evaluated by thermogravimetric analysis (TGA). The crystallization behavior of polypropylene (PP) with unmodified and acetylated bamboo fibers were investigated by differential scanning calorimeter (DSC) and polarizing optical microscope (POM). Accrording to thermogravimetric analysis, the results of thermal decomposition revealed that the shifting of both the onset and max decomposition temperature moved toward higher temperature with the increasing acetylated weight percent gain. Besides, four iso-conversional methods, including Friedman, Flynn-Wall-Ozawa (F-W-O), Starink, and modified Coats-Redfern (modified C-R) were used to determine the thermal decomposition kinetics. The results showed that the activation energies of thermal decomposition between 10% and 70% conversion rates were 167−212, 163−216, 167−226, 155−217, 158−205, and 158−226 kJ/mol for unmodified bamboo fiber and acetylated bamboo fibers with WPG 2, 6, 9, 13, and 19, respectively. The reaction order of unmodified bamboo fiber analyzed by Avrami method (0.47) was lower than that of acetylated bamboo fibers. With regard to the crystallization behavior of polypropylene, the non-isothermal crystallization kinetics were applied to investigate the effects of unmodified and acetylated bamboo fibers on the crystallization behavior of polypropylene. The results showed that the Avrami index (n) were 2.54−3.09 with no significant differences, which implied a heterogeneous nucleation with three-dimensional growth of polypropylene crystals. According to Friedman method, PP with unmodified bamboo fiber showed the highest crystallization activation energy (ΔE) (-130 kJ/mol) while PP with WPG 19 showed the lowest ΔE (-158 kJ/mol). On the other hand, the results obtained from POM under isothermal temperature (130oC) of PP with unmodified and acetylated bamboo fibers showed that the surfaces of unmodified and most of acetylated bamboo fibers were to form transcrystallization, except WPG 19.