纳米TiO2对木纤维/聚丙烯复合材料抗紫外老化性能的影响

木塑复合材料作为室外建筑装饰材料时，暴露在紫外光的照射下,易老化导致其力学性能降低、使用寿命减少。将具有高效紫外线屏蔽能力的金红石型纳米TiO₂经硅烷偶联剂KH-570表面改性后，与木纤维(WF)、聚丙烯(PP)等制备了TiO₂-WF/PP复合材料。对TiO₂-WF/PP复合材料进行了人工加速紫外老化，并利用FTIR、TG、SEM、力学性能分析、颜色变化分析等手段，探究了纳米TiO₂对WF/PP复合材料抗紫外老化的影响。结果表明:改性纳米TiO₂粒子在WF/PP复合材料中均匀分散，无明显团聚，且其加入显著提高了复合材料的热稳定性；TiO₂-WF/PP复合材料随着老化时间的延长，力学性能下降相对较小且颜色变化较小。当纳米TiO₂的质量分数为2 wt%~3 wt%，老化2 000 h时后，TiO₂-WF/PP复合材料的拉伸强度、冲击强度仅分别下降10.0%和12.6%；未加入纳米TiO₂颗粒的WF/PP复合材料，则分别下降20.2%和22.6%。 

Effect of nano TiO2 on UV aging resistance of wood fiber/polypropylene composites

When wood-plastic composites are used as outdoor building decoration materials, they are exposed to ultraviolet light, resulting in mechanical properties and service life reducing. The rutile nano TiO₂ with high-efficiency ultraviolet shielding ability was surface-modified with a silane coupling agent KH-570, and then TiO₂-WF/PP composites were prepared with wood fiber (WF), polypropylene (PP). The artificial accelerated UV aging of the composites was carried out. The effects of nano TiO₂ on the UV aging of WF/PP composites were investigated by means of FTIR, TG, SEM, mechanical properties analysis and color change analysis. The results show that the modified nano TiO₂ particles can be uniformly dispersed in WF/PP composites without obvious agglomeration, and their addition significantly improves the thermal stability of the composites; with the aging time prolonged, the decrease of the mechanical properties of WF/PP composites is relatively small and the color change scope is small. When the mass fraction of nano TiO₂ particles is 2 wt%-3 wt% and aging for 2 000 h, the tensile strength and impact strength of the TiO₂-WF/PP composites only decrease by 10.0% and 12.6%, respectively, while those without the addition of nano TiO₂ particles decrease by 20.2% and 22.6%, respectively.