MALDI-TOF/MS characterisation of LMW PDMS in high voltage HTVsilicone rubber insulators

摘要

This paper reports the results of the characterisation of lowmolecular weight polydimethylsiloxane (LMW PDMS) extracted from fourdifferent brands of high temperature vulcanised (HTV) silicone rubberinsulators designed for high voltage applications. LMW PDMS material wasobtained from the insulators by sequential soxhlet extractions and masschanges were recorded for each extraction. The insulator extracts werethoroughly characterised using matrix-assisted laserdesorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS),which provides identification of individual molecular species allowingdifferences in molecular structure to be identified. The extracts werefound to contain both linear and cyclic species. Some variations in endgroups of the linear species were also noted. These spectra were used tocalculate the relative proportions of these species as well as theaverage molecular weights of the extracts. Significant differences wereobserved in molecular composition and the speed of recovery of theinsulators studied