Wall slip behavior of polymer melts on capillary rheometer
Wall slip behavior of three commercial polymer melts polypropylene(Ipp), low-density polyethylene (LDPE)(branched chains) and high-density polyethylene (HDPE)(linear chains) were studied by using a capillary rheometer with twin bores at different temperatures. The results show that a sudden first-stick-then-slip transition was observed for HDPE and a first-slip-then-stick transition was observed for LDPE and Ipp as the shear rate sweep was done in an increased order, which shows that the chain structure has an obvious effect on the wall slip behavior of polymers. The critical shear stress for the onset of stick-slip transition increases linearly with temperature for HDPE, which accords with the disentanglement mechanism proposed by Brochard and de Gennes. While the extrapolation length used to quantify the magnitude of the transition remains about 0.05-0.09 mm for HDPE at 150-230 ℃. Also the relationship between the critical shear stress for the onset of wall slip and the molecular mass for polymer samples agrees with the disentanglement model of Broehard and de Gennes. The onset of slip-stick transition for LDPE and Ipp at a critical shear stress may be interpreted as the shear thinning of the polymer chains at high shear rates, preventing further development of wall slip behavior.
polymer wall slip critical shear stress capillary rheometer temperature dependence
LIAO Hua-yong(廖华勇) TAN Zhong-xin(谭中欣) ZOU Guo-xiang(邹国享) DING Yong-hong(丁永红) TAO Guo-liang(陶国良)
Polymer Materials Key Laboratory of Changzhou City, Jiangsu Polytechnic University, Changzhou 213164 Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzbou 510640, China
国际会议
长沙
英文
98-101
2008-09-28（万方平台首次上网日期，不代表论文的发表时间）