聚乙烯塑料降解行为及可视化检测研究

Study on Degradation Behavior and Visual Detection of Polyethylene Plastics

摘要: 聚乙烯(PE)塑料因优异性能广泛应用于多个领域，但其稳定性和难降解性，易造成环境污染，因此需要对其降解行为进行检测和评估。本研究选取三种不同用途的PE塑料(保鲜膜、降解点断保鲜膜、降解环保袋)，通过紫外老化试验箱进行光降解处理，结合失重率、紫外可见光谱、红外光谱及罗丹明B染色可视化检测等手段，探究PE塑料的光降解特性。结果表明：1) 254 nm紫外光对PE塑料的降解破坏作用显著强于340 nm；2) 掺杂降解母料的样品降解高于纯PE样品；3) 降解过程中PE塑料分子链断裂，生成共轭双键、C=O、C-O等含氧官能团，导致紫外区反射率下降；4) 老化后的PE塑料因表面极性基团增加、比表面积扩大及孔隙结构形成，与罗丹明B的相互作用增强，荧光强度较未老化样品提升约5倍。

Abstract: Polyethylene (PE) plastics are widely used in various fields due to their excellent properties; however, their high stability and resistance to degradation easily lead to environmental pollution. Therefore, it is necessary to detect and evaluate their degradation behavior. In this study, three types of PE plastics with different applications (PE cling film, degradable perforated cling film, and degradable environmental protection bag) were selected and subjected to photodegradation treatment using an ultraviolet (UV) aging test chamber. The photodegradation characteristics of PE plastics were investigated by combining multiple analytical methods, including weight loss rate determination, UV-visible spectroscopy, infrared spectroscopy, and rhodamine B staining-based visual detection. The results showed that: 1) The degradation and destructive effect of 254 nm UV light on PE plastics was significantly stronger than that of 340 nm UV light; 2) The degradation efficiency of PE samples doped with degradable masterbatch was higher than that of pure PE samples; 3) During the degradation process, the molecular chains of PE plastics were broken, and oxygen-containing functional groups such as conjugated double bonds, C=O, and C-O were generated, which resulted in a decrease in the reflectance of PE plastics in the UV region; 4) After aging, the PE plastics exhibited enhanced interaction with rhodamine B due to the increase in surface polar groups, expansion of specific surface area, and formation of porous structures. Consequently, the fluorescence intensity of aged PE plastics was approximately 5 times higher than that of unaged samples.