Poster: Improvements in Sample Preparation of Polyolefins to prevent Polymer Degradation prior to GPC/SEC and CEF analysis

Benjamín Monrabal, Pilar del Hierro, Alfredo Roig. Polymer Char, Valencia, Spain.

A study of the effects of thermal and oxidation processes on polyolefin degradation

Abstract:

Gel Permeation Chromatography (GPC) – or Size Exclusion Chromatography (SEC) – analysis of polyolefins needs to be performed at high temperature to dissolve the polymer in chlorinated solvents such as 1,2,4-trichlorobenzene or 1,2-dichlorobenzene; this results in a demanding job in both sample preparation and analysis. Besides, sample dissolution has to be performed with care to minimize polymer degradation.

Sample degradation has always been a concern in GPC/SEC analysis of polyolefins due to:

1. The long dissolution time and high temperature required.
2. The potential molecular scission by shearing:
   • in the dissolution step by stirring.
   • in the filtration step going through a frit, or
   • in the analysis by going through the column frits and particles.
3.  Oxidation during the dissolution time in the presence of residual Oxygen in the solvent.

In this paper, the polymer degradation of various polyolefins in the dissolution step is investigated. The degradation level is monitored by the full Molecular Weight Distribution (MWD) displacement and by the molecular weight average (Mw).