Preliminary results in synchrotron X-ray diffraction measurements of rubber composites structure before and after exposure to hydrogen

In future years, fuel cells are expected to represent a promising technology as a source of heat and electricity in buildings and of electrical power for vehicles, since fossil fuels are exhausting and significantly degrade air quality. It is well known that, when exposed to a hydrogen environment, hydrogen embrittlerment may affect materials such as iron and steel. But these are not the only materials that are used for hydrogen equipment. In particular, the rubber materials used for O–rings that seal high pressure hydrogen gas equipment show problems of internal fracture, called blister fracture, when the gas is rapidly decompressed. As many different kinds of fillers can be used, in this work we started to investigate the influence of the type of filler on the rubber composites structure, by means of X-ray diffraction measurements performed at the Elettra synchrotron radiation facility in Trieste. In this preliminary study, three kinds of samples were analyzed before and after exposure to hydrogen: Sulphur vulcanized EPDM, Peroxide vulcanized EPDM and Sulphur vulcanized NBR. While Peroxide vulcanized samples did not show significant differences in the diffraction pattern, changes could be detected in the cristalline form of Sulfure vulcanized rubber.