包装箱用改性聚乙烯在干热气候中的老化行为

摘要

目的 研究包装箱用改性聚乙烯塑料在极端气候环境下的老化特征与规律.方法 在敦煌试验站对改性聚乙烯进行为期36个月的自然老化试验,分析缺口冲击强度的变化规律,采用扫描电镜、傅立叶红外光谱和凝胶色谱技术分析样品曝晒面的显微形貌、微观结构以及分子量及其分布变化情况.结果 户外曝晒3个月时,样品表面出现大量连续裂纹,缺口冲击强度下降约40%,改性聚乙烯在干热环境下的老化以分子链的断链和氧化为主.结论 改性聚乙烯在干热气候中老化迅速,其包装制品在使用中应尽可能减少户外曝晒时间.%Objective To study aging characteristics and laws of modified polyethylene used in packaging-cases in ex-treme climatic environment.Methods The natural aging test of modified polyethylene was carried out for 36 months in Dunhuang test station. Change rules of notch impact strength were analyzed. Scanning electron microscope, Fourier IR and gel filtration chromatography technologies were applied to analyze morphology, microstructure, molecular weight and its distribution change of exposed sample face.Results After 3 months of exposure, many cracks appeared on the surface and the notch impact strength decreased about 40%. Aging of modified polyethylene in dry and hot climate was mainly presented as chain breaking and oxidation of molecular chain.Conclusion The aging of modified polyethylene is rapid in dry-hot environment. The exposure time of its packaging products should be reduced as much as possible.