基于AHP-DEA的聚乙烯热氧老化影响因素灰色关联分析

Grey correlation analysis of influencing factors of polyethylene thermo-oxidation aging based on AHP-DEA

选取具有代表性的八类聚乙烯树脂,进行了64天的热氧老化试验,分析了密度、结晶度、分子量对聚乙烯热氧老化弯曲性能的影响,采用基于层次分析-数据包络法(AHP-DEA)的灰色关联分析法,以灰色关联为中心模型,以AHP-DEA为辅助模型,计算热氧老化时间、老化温度、密度、结晶度、分子量分布对聚乙烯弯曲性能的关联系数,从而定量得出不同因素对聚乙烯热氧老化特性的影响。研究结果表明:在95℃热氧老化条件下,密度越低、结晶度越高、分子量分布越宽的聚乙烯弯曲强度下降越快,且主要集中于老化初期与老化后期。不同因素与聚乙烯老化弯曲性能关联度大小顺序是:结晶度>分子量分布指数>密度>老化温度>老化时间,其中结晶度对聚乙烯老化性能的影响最大,关联度达到了2.857。结晶度越高,聚乙烯缺陷也就越多,在热氧环境中越容易发生氧化,老化现象更严重。

In this work, eight representative types of polyethylene （PE） samples were selected and exposed in accelerated thermo-oxidation environment for up to 64 days. Taking analytic hierarchy procedure （AHP） based grey relational analysis method as the central model and data envelopment analysis （DEA） as the auxiliary model, we quantitatively studied the influence of different factors on PE thermo-oxidation properties by calculating the correlation coefficient between different factors （thermo-oxidation aging time, temperature, density, crystallinity, molecular weight） and PE bending strength. The results showed that lower of density, higher degree of crystallinity and wider molecular weight distribution of PE results in faster decrease of the bending strength which was mainly concentrated in the early and latter part of aging. The order of relational degree between different factors and PE bending strength was crystallinity, molecular weight distribution （MWD）, density, aging temperature and aging time. In the internal factors, crystallinity had the greatest influence on PE thermo-oxidation aging property, with a correlation degree of 2.857. The higher the crystallinity, the more the flaw in PE, which facilitates the oxidation under thermo-oxidation environment and the aging phenomenon gets more severe.