一种新型老化评价系统及在聚乙烯复合材料中的应用

建立了一种高灵敏度、多环境因素耦合的新型老化评价系统,可以实现在光、热、氧、湿等多种环境因素条件的耦合下,对高分子材料快速、灵敏、实时、无损的老化评价.该系统被用于聚乙烯(PE)复合材料的稳定性和老化状态的评价以及PE老化动力学的研究.结果表明,该系统测定的CO2生成速率与PE复合材料自然老化下的氧化程度具有良好的对应性,同时能够精确反映PE复合材料的自然老化状态—不同自然老化时间的PE复合材料,其CO2生成速率与羰基指数的对数呈线性关系.此外,该系统还可以快速、准确地测定PE老化过程的活化能.

A Novel Aging Evaluation System and the Application to Polyethylene Composites

A novel aging evaluation system has been developed to realize a rapid, sensitive, non-destructive aging evaluation of polymer materials under various environmental conditions. Available conditions include irradiation, temperature, oxygen and humidity. This system can be used in the stability evaluation, aging status analysis and aging kinetics measurement by in situ detecting trace gaseous degradation products, such as CO2, in a specially designed reaction cell by FTIR. In this study, polyethylene(PE) composites were used as an example.The generation rate of CO2 of PE composites during a 4-h in situ detection corresponded well to the carbonyl index during a 120-day natural weathering, and the same stability ranking was obtained. In particular, there was a linear relationship between the generation rate of CO2 and the natural logarithm of carbonyl index, indicating that the generation rate of CO2 could be taken as a new evaluating index to rapidly detect aging status of PE composites. The activation energy of PE photo-oxidative aging was calculated based on the generation rates of CO2 at different temperatures in the range of 30-80 ℃, which was in agreements with the results reported in literature. The above facts prove the reliability and efficiency of this novel aging evaluation system. Meanwhile,the high sensitivity of the system would enable the determination of activation energies at low temperatures close to the actual operating conditions of materials, avoiding the uncertainty caused by the extrapolation of accelerated results from high temperature.