Surface Degradation Analysis of Semi-conductive Rubber by Micro Sampling Mass Spectrometry

Abstract

Micro sampling mass spectrometry (μ-MS) is a newly developed small area microanalysis method. It gives information on the chemical structure of polymers by means of direct mass. It also gives information on the scission and crosslinking of rubber molecules based on TIC (Total Ion Chromatogram) peak shift.
The degradation analysis of NBR and epichlorohydrin rubber was carried out by infrared micro spectroscopy and μ-MS. Samples were prepared by three different treatments, heat as well as ultraviolet (UV) and electron beam (EB) radiations. It was found for NBR vulcanizates that the heat treatment induced the oxidation, scission and crosslinking of rubber molecules. By the UV treatment, chain scission and crosslinking accompanied by a slight oxidation were induced. The EB treatment enhanced the crosslinking, however, the extent of oxidation was negligible. For epichlorohydrin rubber vulcanizates, the heat treatment accelerated chain scission rather than crosslinking. On the other hand, the oxidation and crosslinking were induced by the UV and EB treatments.
The surface of a semi-conductive NBR roller was covered with oxides and low molecular weight compounds after the roller durability test. Furthermore, crosslinking was induced in the layer under them.