聚氯乙烯塑料光催化降解行为的检测研究

Detection and Research on Photocatalytic Degradation Behavior of Polyvinyl Chloride Plastics

摘要: 本研究以锐钛型纳米TiO₂为光催化剂，选取PVC保鲜膜、PVC透明软胶板、PVC收缩袋三种不同用途的PVC塑料为研究对象，通过浸渍/浸涂法制备催化降解样品，在40℃紫外老化箱中进行加速老化实验，结合失重率测定、紫外可见光谱及红外光谱分析，探究纳米TiO₂对PVC塑料的光催化降解行为。结果表明：纳米TiO₂能显著加速PVC塑料的光降解，其中保鲜膜在催化条件下3 d失重率达26.6%，远高于无催化剂时的12.7%；收缩袋的催化降解效果同样显著，透明软胶板因材质较厚、含抗老化剂及吸光物质，降解程度最低，最大失重率低于4%。紫外可见光谱显示，催化降解样品在250~400 nm紫外区反射率显著降低，表明生成了C=C共轭双键等吸光成分；红外光谱证实，PVC降解过程中C-Cl键、C-H键及增塑剂相关的C-O-C键发生断裂，符合脱氯化氢的降解机理。

Abstract: In this study, anatase-type nano-TiO₂ was used as the photocatalyst, and three types of PVC plastics with different applications—PVC cling film, PVC transparent soft rubber sheet, and PVC shrink film—were selected as the research objects. Catalytic degradation samples were prepared via the dipping/doctor-blading method, and accelerated aging experiments were conducted in an ultraviolet (UV) aging chamber at 40˚C. Combined with weight loss rate determination, UV-Vis spectroscopy, and FT-IR spectroscopy analysis, the photocatalytic degradation behavior of PVC plastics by nano-TiO₂ was investigated. The results showed that nano-TiO₂ could significantly accelerate the photodegradation of PVC plastics. Among them, the weight loss rate of the cling film reached 26.6% after 3 days under catalytic conditions, which was much higher than the 12.7% observed without the catalyst. The catalytic degradation effect on the shrink film was also significant. However, the transparent soft rubber sheet exhibited the lowest degradation degree (with a maximum weight loss rate of less than 4%) due to its thicker material, as well as the presence of anti-aging agents and light-absorbing substances. UV-Vis spectroscopy results indicated that the reflectance of the catalytically degraded samples decreased significantly in the UV region of 250 - 400 nm, suggesting the formation of light-absorbing components such as C=C conjugated double bonds. FT-IR spectroscopy confirmed that the C-Cl bonds, C-H bonds, and C-O-C bonds related to plasticizers in PVC were broken during the degradation process, which is consistent with the degradation mechanism of dehydrochlorination.