Modified Entanglement Structure: Model and Comparison with Experiment

Abstract

The outline of a model is presented to depict the entanglement states of polymers. Polymer melts are regarded in the model as composed of two components. Free macromolecular chains form the first component and the network of the entangled macromolecular chains the second. The state variables chosen to describe the internal structure of the polymer melt are: two conformational tensors (each describing one component) and another scalar that represents the relative proportion of each component (i.e., related to the entanglement density). The equations governing the time evolution of the state variables and the corresponding formula for the extra stress tensor are suggested with the help of recently developed diffusion-convection equations. The model provides a convenient framework for the study of changes in the entanglement structure due both to different types of preparation of the polymers and to flow. Rheological data for two types of polyolefins either modified or unmodified are used to make preliminary assessment of the model. © 1989, The Society of Rheology. All rights reserved.