显微红外光谱法研究聚乙烯复合材料光氧化的深度分布

采用显微红外光谱法结合表面形貌分析研究了分别填充碳酸钙、绢英粉、云母、高岭土和硅藻土的高密度聚乙烯(HDPE)的自然光氧化随深度的分布。研究结果表明无机填料对HDPE光氧化的深度分布有很大的影响。填充碳酸钙的HDPE从表面到内部都没有明显氧化发生。而填充绢英粉、云母、高岭土和硅藻土的HDPE从表面到内部羰基指数逐渐减小，氧化深度都在150 μm以上。HDPE复合材料沿深度方向的氧化情况与其断面裂纹的产生情况吻合。结合无机填料的紫外吸收特性讨论了它们对HDPE光氧化的影响机理。

Depth Profiles of High-Density Polyethylenes Filled with Different Inorganic Fillers during Natural Photo-Oxidation by Infrared Microscopy

The natural photo-oxidation degradation of HDPE filled with different inorganic fillers was carried out, and the depth profiles of the standard samples were characterized by infrared microscopy (IM) and scanning electron spectroscopy (SEM). The results show that HDPE filled with different inorganic fillers show different depth profiles. For HDPE and CaCO_3-filled HDPE, there are no cracks on the cross sections, and the carbonyl indexes remain nearly zero from the surface to the interior. For HDPE filled with black mica, mica, kaolin and diatomite, there are more or less parallel, comb-like cracks on the cross sections, and the carbonyl indexes show decreasing trends from the surface to the interior. Furthermore, the transition points in CI curves are basically consistent with the formation of cracks in these samples. The UV absorbances of these inorganic fillers demonstrate the relationship between the photo-oxidation of HDPE and the relative absorbances of inorganic fillers. This implies that the UV absorbance of the inorganic filler may be responsible for the occurrence of cracks and oxidation in the standard samples.