彩色木塑复合材料的老化性能

Aging Properties of Colorful Wood Plastic Composites

向桦木粉/高密度聚乙烯(HDPE)复合材料中添加白色、黄色和红色着色剂,采用热压成型工艺制备彩色木塑复合材料。研究着色剂种类及含量对木塑复合材料力学性能和表面颜色的影响,同时分别考察彩色木塑复合材料在户外自然老化和紫外光加速老化箱中的老化情况,分析讨论其老化机制。结果表明:添加着色剂可提高木塑复合材料的力学性能,改善材料的外观颜色;木塑复合材料的力学强度和总色差随着色剂用量的增加而逐渐增大,当着色剂用量为3.5wt%时,复合材料的性能达到最佳;木塑复合材料经老化实验后表面褪色明显且力学强度显著降低,但自然老化后其性能下降更明显。这主要是因为木塑复合材料在老化过程中,不仅受到紫外光的照射发生了光降解,而且长期被雨水冲刷导致材料表面的桦木纤维及着色剂大量剥落,降低了材料界面结合强度,从而导致材料性能明显下降。

Colorful birch flour/high density polyethylene（HDPE） composites added with white, yellow and red color agents were prepared by hot-pressing technology. Effects of species and content of color agents on the mechanical properties and surface color of the composites were determined. Moreover, the aging mechanism of birch flour/HDPE composites treated by outdoor natural aging and UV accelerated aging were analyzed. The results show that the mechanical properties of the birch flour/HDPE composites could be improved effectively and their surface color could be changed by filling color agents. After the color agents added into the birch flour/HDPE composites, their mechanical strength and total color difference increase with the increase of color agent content. When the content of color agent is 3.5wt%, the properties of birch flour/HDPE composites reach the best. After treated by natural aging, the birch flour/HDPE composites fade obviously and their mechanical properties decrease slightly due to the surface photo degradation of composites caused by the UV irradiation and the surface of composites were long washed by rain. Moreover, the properties of the composites decreased obviously due to the interface bond strength reduction by the birch fibers and color agents on the surface flaking.