| Summary: | 碩士 === 國立中正大學 === 化學工程研究所 === 87 === 英文摘要
The molecular weight and molecular weight distribution of polymer liquids have significant effects on their rheological properties. In this research, we study the effects of polydispersity on the linear viscoelasticity of polymer melts. In the past, the Doi-Edward model has been used to predict the linear viscoelasticity of polymer melts; however, since the model does not account for the effect of constraint release, it cannot properly describe the linear viscoelasticity of the blending systems. Therefore, we here employ a modified reptation model that can account for the effect of constraint release to simulate the linear viscoelastic properties of polydisperse polymer systems. Simulation results are compared with the predictions of the experimental mixing formula, the mixing rule, for the linear viscoelastic properties. We find that the predictions of the modified reptation model improve those of the Doi-Edward model for a binary system, but do not satisfy the result from the mixing rule. Therefore, we have added another effect that accounts for extra constraint releases of the long chains when a short chain reptates away. We find that after such a modification, the model is able to predict the mixing rule for a ternary blending system. And we believe that the current scheme should also apply to the general polydisperse systems on predicting the linear viscoelastic properties.
|
|---|
