Elongational Flow of Solution Treated Ultra-high Molecular Weight Polyethylene

Abstract

The experimental study of elongational flow for solution treated ultra-high molecular weight polyethylene (polyethylene gel) was carried out using an elongational rheometer. Three different molecular weight polyethylenes, Mw=1.0×10n, 2.0×106, 2.5×106 were used. Solutions were prepared by dissolving 10wt% of the polyethylenes in decalin. The solution treated ultra-high molecular weight polyethylenes were uniformly elongated in constant strain rate elongation experiments. The elongational viscosity-time relation at 140°C shows the same behavior as polymer melts except at high viscosity. The elongational strain (draw ratio) at high temperature are much smaller than that in lower temperature experiments. A rapid increase in elongational viscosity appears at ca. 200sec for strain rate of 0.008sec-1. The degree of the viscosity increase of the solution treated polyethylene is much steeper than that of polymer melts. The steep increase in the viscosity was discussed in terms of the structure development of the solution treated polyethylene.