Abstract: The surface of nano-rutile-TiO₂ was modified by silane coupling reagent A-172 and the TiO₂ were characterized by FTIR and TEM techniques. According to the spectra of FTIR, it can be inferred that the A-172 was bound on the surface of nanosized TiO₂. Transmission electron microscopy pictures showed that the hydrophobicity of nanosized TiO₂ modified with A-172 was improved. The modified nano-TiO₂ (0.5%, 1%, 1.5% and 2%)was added to polyglycolic acid (PGA)as the ultraviolet ray shielding, and a series of PGA composites were prepared. The accelerated aging test of pure PGA and PGA/nano-TiO₂ composites was carried out with laboratory xenon arc lamp. The results showed that the modified nano-TiO₂ could be well dispersed in PGA so that the PGA had a wider UV absorption range and a stronger UV absorption peak. And the aging resistance of PGA was remarkably improved. The modification effect was optimum when the mass fraction of modified nano-TiO₂ was 1.5%, and the yellowness index of modified PGA just increased 4.1. Tensile strength and notched impact strength retention rate were 56.34% and 65.15%, respectively, increased by 42.29% and 37.21%. And weight average molecular weight and number average molecular weight retention were also increased by 33.64% and 33.99%, respectively.

Key words: nano-rutile-TiO₂, surface, polyglycolic acid (PGA), dispersion, accelerated aging

摘要： 用硅烷偶联剂（A-172）对金红石型纳米TiO₂进行有机表面改性，采用红外光谱（FTIR）、透射电镜（TEM）对改性结果进行了表征。红外光谱表明，A-172以化学键的方式结合在纳米TiO₂表面；透射电镜照片表明，改性后的纳米TiO₂表现出较强疏水性。将改性后的纳米TiO₂作为紫外线屏蔽剂添加到聚乙醇酸（PGA）中，分别制备了TiO₂质量分数为0.5%、1%、1.5%和2%的复合材料，并采用氙灯气候试验机对纯PGA和PGA/纳米TiO₂复合材料进行加速老化对比试验。实验结果表明，改性后的纳米TiO₂在PGA材料中具有良好的分散性，使PGA具有更宽的紫外吸收范围和更强的紫外吸收峰，其中，当添加质量分数为1.5%时改性效果最佳，经过800h加速老化后，复合材料黄色指数只增加4.1，拉伸强度和缺口冲击强度保持率为56.34%和65.15%，分别比纯PGA提高了42.29%和37.21%，重均分子量和数均分子量保持率也分别提高了33.64%和33.99%。

关键词: 金红石型纳米TiO₂, 表面, 聚乙醇酸, 分散, 加速老化