Evaluation of the change in chemical structure of acrylonitrile butadiene rubber after high-pressure hydrogen exposure

The influence of high-pressure hydrogen on the chemical structure of organic materials is essential for designing suitable materials for the safe and efficient use of hydrogen. In this paper, we clarify the cause and mechanism of “explosive failure by decompression” (XDF) in rubber used under high-pressure hydrogen circumstances, and the chemical structure of acrylonitrile butadiene rubber (NBR), which is commonly used for O-rings, was analyzed after exposure to hydrogen at 100 MPa. Solid-state nuclear magnetic resonance (NMR) and liquid-phase NMR for 1H and 13C, as well as infrared and Raman spectroscopy, were employed for the evaluation. The results show no evidence of structural changes in NBR such as hydrogenation of the olefinic bonds in butadiene or of the cyano groups in acrylonitrile.

► A precise method to evaluate hydrogenation in NBR using 1H NMR was established.
► NMR, IR and Raman ensured no change in chemical structure of exposed specimen.
► Chemical structure of NBR does not change by hydrogen exposure of XDF condition.
► The cause of XDF must be mechanically dissolved hydrogen without chemical reaction.