聚合物熔体跨尺度挤出过程的黏弹性流变特性

Viscoelastic Rheological Properties of Polymer Melts in Cross-scaleExtrusion Processes

在聚合物熔体微尺度动态黏弹特性实验的基础上,基于分子理论建立了跨尺度挤出过程中的熔体黏弹特性微尺度效应流变模型。流变模型反映了流道特征对黏弹性流动过程应力状态的影响。微尺度效应弱化了熔体的黏弹性流变响应,促进了分子链松弛。模型的微尺度效应通过储能模量和耗能模量的微尺度效应系数及二者的比值表征。微尺度效应系数越小,特征尺度对黏弹特性的影响越显著;黏弹性微尺度效应系数比值越小,特征尺度对松弛过程的影响越明显。

A molecular theory-based rheological model was established to describe micro-scale effect on viscoelastic rheological properties through dynamic viscoelastic property measurements under micro-scale conditions.The model might reflect influences of characteristic channels on the stress state of viscoelastic flow processes.The existence of micro-scale effect weakened viscoelastic rheological response of polymer melts and promoted relaxation processes of molecular chains.The micro-scale effect included in the rheological model was characterized by coefficient sizes of micro-scale effect and ratio of storage modulus and loss modulus.A smaller value of the coefficient for the micro-scale effect indicates a more remarkable effect of the characteristic scale on the viscoelastic properties.Smaller ratio of coefficients for viscoelastic micro-scale effect shows an apparent influence of characteristic scale on the relaxation processes.