Effect of full chain-stretch on the rheology of H-shaped polymer in the single step-strain flow

• Main Authors: Shie Sheng Chang, 謝盛昌
• Other Authors: Hua Chi Chung
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/45676731447405736382

碩士 === 國立中正大學 === 化學工程研究所 === 89 === Molecular modeling on the rheology of H-shaped polymer melts has been based on the recently proposed pom-pom model（McLeish and Larson, J. Rheol. 42, 81（1997））. While being very successful in predicting linear viscoelastic properties, this model, however, cannot predict satisfactorily the nonlinear stress relaxations. Here we consider a possible modification that concerns primarily the chain-stretch mechanism of the backbone polymer. Direct comparisons with an existing set of experimental data on H-shaped polyisoprene melts （McLeish et al. Macromolecules 32, 6734 （1999）) reveal that the current modification is able to lead to excellent quantitative agreement with the data for strain magnitudes from 0.1 up to 10 for single step-strain flows. Molecular mechanisms essential for the above improvement are discussed.