Melt Viscosity of Low Pressure Polyethylene

II. The Flow Properties of Various Low Pressure Polyethylenes

Abstract

The flow properties of nine samples of low pressure polyethylene (Hizex A, B, C and D, Marlex 50, Hostalen GD, GF, GM and Hifax) and two samples of high pressure polyethylene (Tenite and Dow Chemical Polyethylene) were investigated. The experiments were carried out using a capillary viscometer. The relationship between Mν, and initial viscosity η₀ for the low pressure polyethylene Hizex ranging in number-average molecular weight from 16, 500 to 155, 000 and in melt viscosity η₀ from 3×10² to 4×10⁵ poises can be expressed numerically by the following equations: logη₀=3.1logMν-10.7 (200°C) logη₀=3.1logMν-11.0 (240°C) The low pressure polyethylene generally has smaller activation energy for viscous flow than the high pressure polyethylene. When the values of exponent N (in D=aτ_w^N) are plotted as a function of the logη₀ for these polyethylenes, fairly good linear relations are obtained. The fact that even though Marlex 50 has fairly large A, it has much smaller η₀ and N than the other low pressure polyethylenes is one of the characteristics of Marlex 50 polyethylene.