聚丙烯在30℃下的应力松弛行为及其模型模拟分析

Stress Relaxation Behavior of Polypropylene at 30℃and Its Model Simulation Analysis

对全同聚丙烯(iPP)和无规共聚聚丙烯(PPR)在拉伸温度为30℃的应力松弛行为进行研究,不同结晶度的聚丙烯残余应力是不同的。采用广义七元件Maxwell模型对不同结晶度的iPP和PPR应力松弛行为进行模拟。由该模型建立了对应的方程,方程中的参数反映了聚合物的聚集态结构在应力松弛过程中的变化。结果表明,该模型能较好地描述应力松弛行为。模型中各参数的变化通过归一化处理进行分析。根据模型方程归一化参数的结果,发现材料的结晶结构在应力松弛过程中发生了变化。X-射线衍射仪(XRD)和差示扫描量热仪(DSC)对结果进行了验证。

Isotactic polypropylene and polypropylene random copolymer were investigate for stretch stress relaxation behavior at 30℃.The residual stress of PP with different crystallinity was various.The generalized Maxwell model of seven elements was used to model the stress relaxation behavior of iPP and PPR with different crystallinity.The corresponding equation was established by the model and the parameters in the equation represented the characteristics of structural unit of polymer in the process of stress relaxation.The results revealed the model could describe stress relaxation behavior.The significance of each parameter in the equation was analyzed by normalized parameters.According to the result of normalized parameters in the model equation,it was found that the crystallinity of materials changed in the process of stretch stress relaxation.XRD and DSC proved the results.