Study on the Viscoelastic Properties of Polymer Melts in Shear

• Main Authors: Hong-Zhi Wang, 王宏志
• Other Authors: Hsieng-Cheng Tseng
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/94099890965939772911

碩士 === 國立臺灣科技大學 === 化學工程研究所 === 83 === The objective of this work is to study the viscoelastic properties of polymer melts, including PP, PS and LDPE under shear and elongational deformation. The shear viscosity of polymer melts were measured by a rheometrics dynamic analyzer (RDA) and a capillary rheometer. The modified Cross model was employed to correlate the shear viscosity data for the various polymer melts. The elongational viscosity of polymer melts were calculated from the shear viscosity data by both the Cogswell model and the Binding model. Since the experimental data of elongational viscosity at high deformation rates were not available, the calculated elongational viscosities were compared to those predicted by the Larson model. The experimental data of elongational viscosity obtained by the melt spinning method at moderate deformation rates were also compared to those predicted by the Larson model. The results were found to be satisfactory. The fact that the Trouton ratio predicted by the Larson model is close to the theoretical value of three assures that the Larson model is reliable. In the calculation of elongational viscosity by the Cogswell model, it was found that the true shear viscosity data were more relevant than the apparent viscosity data.The elongational viscosities calculated by the Binding model were found to be more closer to those predicted by the Larson model than those calculated by the Cogswell model.