6. Effects of layered double hydroxide (LDH) on wood flour/polypropylene composites during accelerated UV weathering

摘要

Wood-plastic composites (WPCs) have proven to be an ideal material due to their economic and mechanical advantages. The expanding utilization of WPCs in outdoor applications results in a need to protect them from weathering. Layered double hydroxide (LDH), also called anionic clays, are now used in various applications, such as catalysts, fire retardant additives, UV absorbents, and so on. In this research, a layered double hydroxide, MgAl-CO3-LDH, was synthesised and its effects on the photostability of wood flour/polypropylene (WF/PP) composites during weathering were investigated. WF/PP composites with different LDH loading levels were prepared and tested in a QUV accelerated weathering tester for a total 960 h. The surface color, surface gloss, and flexural properties of the composites were tested, accompanied by characterizations using SEM, ATR-FTIR, and TG. The results indicated that (1) the flexural properties of LDH-loaded composites were improved; (2) composites containing LDH showed less discoloration, fewer surface cracks, and less loss of flexural strength and modulus than control group; (3) LDH played a positive effect on alleviating the photo-oxidation process of WF/PP composites, confirming its UV-shielding effect; (4) LDH enhanced the thermal stability of composites before and after weathering.