Natural weathering properties of acetylated bamboo plastic composites

The hydrophilic properties of lignocellulosic materials pose problems when they are used as reinforcement in plastics. The hydrophilicity of lignocelluloses influences its durability and also the interfacial adhesion between lignocellulose and polymers. Chemical modification, especially acetylation, has been used successfully to decrease the hydrophilicity and increase the weathering resistance of lignocellulose. Therefore, the purpose of this study is to investigate the natural weathering properties of bamboo plastic composites (BPCs) reinforced with bamboo fibers acetylated to different weight gains (WGs). The results showed that the retention ratios of mechanical properties of acetylated BPCs, especially those containing fibers with a high WG, were significantly improved as compared to the unmodified composite during natural weathering. In addition, the crystallinity of the high-density polyethylene (HDPE) in all BPCs increased after natural weathering for 120-240 days and then leveled off. This result indicates that the chain scission of HDPE mainly occurred during this period, producing shorter and more mobile chains and enabling them to undergo secondary crystallization. Furthermore, the mildew resistance of the acetylated BPCs was higher than that of unmodified composite. These results indicate that the durability and decay resistance of BPCs can be enhanced through acetylation of the bamboo reinforcement. (C) 2012 Elsevier Ltd. All rights reserved.