支化高分子熔体粘弹性本构行为的比较

Comparison of Viscoelastic Constitutive Behavior for Branched Polymer Melts

首先给出表征XPP、DCPP和S-MDCPP 3种粘弹性本构模型流变特性的物料函数,比较了它们对稳态简单剪切和稳态单轴拉伸流动中熔体复杂流变行为的预测能力。结果表明,S-MDCPP本构模型能够较好地反映实际支化高分子熔体的复杂流变行为。最后,讨论了S-MDCPP本构模型中各参数(主链末端支链数q、取向和拉伸松弛时间之比r以及滑移系数ξ)对熔体流变行为的影响。分析表明,主链末端支链数q以及取向和拉伸松弛时间之比r均对熔体的拉伸黏度影响较大,随着q的增加或r的减小,熔体黏度均呈现增加的趋势;随着滑移系数ξ的增加,熔体的剪切黏度降低。

The material functions of the XPP, DCPP and S-MDCPP viscoelastic constitutive models were given to characterize the theological behaviors, and then the predictive capabilities of the three models for steady simple shear flow and steady uniaxial elongational flow were compared. The results show that the S-MDCPP model is capable of well capturing the rheological behavior of branched polymer melts. Moreover, the effect of parameters （the amount of arms at the end of a backbone q, the ratio r of λOb to As, and slip coefficient ） of S-MDCPP model on the responses of rheological behavior of polymer melts was discussed. The analyses results show that q and r have a significanl impact on the dimensionless elongational viscosity of polymer melts, and viscosities increase with increasing of or decreasing of r. The dimensionless shear viscosity of polymer melts decreases with increasing of slip coefficient .