Impedance spectroscopy for in situ and real-time observations of the effects of hydrogen on nitrile butadiene rubber polymer under high pressure

摘要

Nondestructive impedance spectroscopy (IS) was developed and demonstrated to detect the effects of hydrogen on nitrile butadiene rubber exposed to hydrogen gas (Hsub2/sub) at high pressures up to 10?MPa. IS was applied to obtain an in situ and real-time quantification of Hsub2/sub penetration into and its desorption out of rubber under high pressure. The diffusion coefficients of Hsub2/sub were also obtained from the time evolution of the capacitance, which were compared with those obtained by thermal desorption gas analysis. The in situ measurements of the capacitance and the dissipation factor under various pressures during cyclic stepwise pressurization and decompression demonstrated the diffusion behaviour of Hsub2/sub, the phase of the rubber under high pressure, the transport properties of Hsub2/sub gas, and the physicochemical interaction between Hsub2/sub and the rubber. These phenomena were supported by a COMSOL simulation based on the electric current conservation equation and scanning electron microscopy (SEM) observations.