Non-Newtonian rheological behavior of semi-dilute ultra-high molecular weight polyethylene solution in gel-spinning process. 1: Concentration effect on the fundamental rheological properties

The rheological properties of a semi-dilute ultra-high molecular weight polyethylene (UHMw-PE)/paraffin wax solution were investigated by mainly focusing on the influence of its concentration on the shear flow viscosity. It was found that the UHMw-PE solution exhibits a shear thinning behavior at a very wide shear rate range from 10(-4) to higher than 10(3) sec(-1). Furthermore, this typical non-Newtonian behavior was more obvious with a concentration increase. From the concentration dependence of the zero-shear creep compliance or other rheological factor, it was found that the extremely large M-e value of the system gives rise to various kinds of non-Newtonian behaviors, especially those highly elastic in nature. Finally, the origin of the abnormal stress fluctuation during the steady shear measurement was found to be related to the shear-induced structural development of the solution.