A Comparative Investigation of the Rheological Properties in Shear and Tension of Tube-Grade Polymodal Polyethylene Melts

Abstract

Melts of bimodal (tube) polyethylenes relax considerably more rapidly than normal monomodal specimens. At exit from an l/d = 20 capillary, a melt of bimodal polyethylene behaves like an unrelaxed melt, whereas normal polyethylene does not manage to relax entirely even at exit from an l/d = 30 capillary. The obtained results point to one of the reasons for the high durability of polyethylene tubes with a bimodal molecular weight distribution.