论文部分内容阅读
Studies on the viscoelastic behavior of styrene- [ethylene-(ethylene-propylene)]-styrene block copolymer (SEEPS) were carried out, and some characteristic viscoelas-tic parameters were calculated. The longest relaxation time τmax was obtained through simulating the relaxation spec-trum on the basis of a modified Baumgaertel-Schausberger- Winter (mBSW) model. The results revealed that there exists a “second plateau” in the low frequency region of the master curves. The reason for this phenomenon is attributed to the entanglement of macromolecular chains. It is suggested that the hard blocks, polystyrene, act as entanglement points, resulting in a topology restraint to the movement of macro-molecular chains. Meanwhile, it is found that the horizontal shift factors (aT) vs temperature in the master curve could be fitted to the Williams-Landel-Ferry (WLF) equation and Ar-rhenius equation respectively and the flow activation energy (Ea) is 127.88 kJ/mol. In addition, the plateau modulus (GN0) and entanglement molecule weight (Me) were calculated.
Studies on the viscoelastic behavior of styrene- [ethylene- (ethylene-propylene)] - styrene block copolymer (SEEPS) were carried out, and some characteristic viscoelas- tic parameters were calculated. The longest relaxation time τmax was obtained through simulating the relaxation spec The results for that there exists a “second plateau” in the low frequency region of the master curves. The reason for this phenomenon is attributed to the entanglement of It is suggested that the hard blocks, polystyrene, act as entanglement points, resulting in a topology restraint to the movement of macro-molecular chains. Meanwhile, it is found that the horizontal shift factors (aT) vs temperature in the master curve could be fitted to the Williams-Landel-Ferry (WLF) equation and Ar-rhenius equation respectively and the flow activation energy (Ea) is 127.88 kJ / mol. s (GN0) and entanglement molecule weight (Me) were calculated.