高密度聚乙烯DSC原位加速热老化特性研究∗

摘要

The degradation properties of high density polyethylene (HDPE)by DSC in-situ accelerated thermal aging were studied.The effect of thermal aging temperature on melting characteristic,crystallinity and microstructure were studied.The relationship between factors was explored by principal components analysis (PCA)and the com-bined evaluating parameter of HDPE under different thermal aging temperature was established and analyzed.The re-sults showed that the cross-link effect is predominant under low thermal aging temperature,and the branching degree and chain scission are aggravated and oxidation products are increased with temperature increasing.The chain scission in the amorphous leads to the increase in chain mobility and the crystallinity rise first and then fall.The peak tempera-ture and final temperature,vinylidence,branching degree,chain scission and carbonyl index are strongly correlated, the peak temperature and final temperature are negatively correlated with the vinylidence and chain scission.The com-bined evaluating parameter Z characteristics presents two-stage changes trend.%利用DSC原位加速热老化方法，研究了高密度聚乙烯(HDPE)热老化特性，分析了热老化温度对HDPE熔融特性、结晶度和微观结构的影响，通过主成分分析法(PCA)探究了参数变化的相关关系，建立并评估了HDPE在热老化条件下的老化综合评价指标。结果表明，在较低热老化温度条件下，交联作用占主导，随着老化温度的升高，断链与支化作用加强，氧化产物生成变多，由于非结晶区分子链断裂，增强了分子链的活动性导致结晶度先上升后下降。峰值温度和终止温度与亚乙烯基、支化程度、断链程度和羰基指数协同相关程度高，峰值温度、终止温度与亚乙烯基、支化程度互为强抵抗相关。老化综合评价指标整体上Z值呈现两段式的变化趋势。