聚合物熔体的非仿射网络结构模型及其数值解

假设聚合物熔体的缠结网络形变是非仿射的，运用瞬态网络结构原理。并利用Liu提出的动态速率方程以及上随体Maxwell本构方程来建立一个适合于振动剪切作用下的聚合物熔全非仿射网络结构模型。利用这一模型来研究振动剪切作用下LDPE和HDPE熔体的流变行为。研究表明，在一种合理的初始简化条件下可以获得模型的数值解。将理论预测值与实验值进行比较后得知二者具有良好的吻合性，从而简化了模型的计算过程。同时，通过比较得知所建立的非仿射网络结构本构方程比仿射网络结构本构方程的精确度要高，而且在振动力场作用下。具有长支链的LDPE熔体有少量的非仿射网络形变，而没有长支链的HDPE熔体则有较多的非仿射网络形变。因此在建立振动力场作用下聚烯烃熔体本构方程时应充分考虑聚合物熔体网络的非仿射形变。

Nonaffine Network Structural Model of Molten High Polymer and its Numerical Analyzes

By use transient network structural theory with Liu's kinetics rate equation and the upper con-vected Maxwell constitutive equation to establish a nonaffine network structural constitutive model for studying the rheological behavior of molten Low-Density Polyethylene (LDPE) and High-Density Polyethylene (HDPE) in oscillatory shear the molten polymer's entanglement network deformation was proposed as nonaffine. As a result, with the simplified initial condition, its numerical solves could be easy to gotten. Accordsing with the experimental data, the precision of the nonaffine network structural model is higher than that of affine network structural model. It is also clear that there is a small amount of nonaffine network deformation for LDPE melts which have long-chain branches, and there is a larger amount of nonaffine network deformation in oscillatory shear for HDPE melts which has no long-chain branches. When the constitutive equations of polymer melts for oscillatory shear was established the network deformation nonaffine must be considered.