A study of the degradation of polyethylene by high‐temperature dynamic light‐scattering

Abstract

AbstractAfter passing throught an extuder, a small amount of degradation normally occurs in the high molecular weight tial of a broadly distrubuted polymer sample. This small amount of degradation counld dramatically affect the polymer viscoelastic properties. It is difficult to detect this type of degradion by using convetional analytical methods, such as hightemperature size exculsion chr omatography. An investisgation of this thype of degradation in a broadly distributed polyethylene sample was accomplished by using high‐temperature dynamic light‐scattering (HTDLS). We have shown that the measured line‐width (or the tsranslatinal diffusion coefficient) distrubuiton in the HTDLS is proportional to Mα with α = 3. 580 ± 0.005 so that the HTDLS is a very sensitive techique for detecting a very small amount of degradation im the high molecular weight tail. Another advantage of using the HTDLS is that the study does not intoduce further stress or perturbation into the sample. In study, we also investigated the thermal degradation of the polyelthylene sample in trichlorobenzene at high temperatures. We found that the polyethylene sample after the extrusion undergoes a thermal degradation more easily. © 1994 John Wiley & Sons, Inc.