Study on the expansion of nitrile rubber in high-pressure hydrogen gas atmospheres: Calculations and experiments

Hydrogen with small molecule size under high pressure can permeate most materials, being a challenge for rubber sealing materials used in hydrogen storage. The volume expansion of rubber materials due to high-pressure hydrogen is an important indicator of their degradation and failure. Here, both microscopic calculations and experimental investigations of the nitrile rubber were conducted to evaluate the relation between the structure features and the expansion performance. Three factors, the acrylonitrile amount, the chain length, and the crosslinking degree, were considered to impact on the expansion of the nitrile rubber. Current study indicates that the increasing of acrylonitrile amount can result in the reduction of the volume expansion, owing to the preferential interactions between hydrogen and the butadiene group of nitrile rubber. Both of the chain length and the crosslinking degree are positively proportional to the chain elongation and then the volume of the nitrile rubber. Especially, the amount of acrylonitrile was found to be a key factor for evaluating the expansion of nitrile rubber under high-pressure hydrogen. This study performs microscopic calculations and macroscopic experiments to investigate the expansion of nitrile rubber, which is expected to be used in designing the sealing rubber material for high-pressure hydrogen storage applications.Highlights Acrylonitrile determines the expansion performance of NBR within high-pressure hydrogen. Short chain and low crosslinking density suppressed the expansion of NBR. Evaluating the expansion of nitrile rubber exposed to high-pressure hydrogen. Volume expansion of nitrile rubber in high-pressure hydrogen gas atmospheres. image