Hydrogen sorption and desorption properties in rubbery polymer

Abstract

We firstly characterized the sorption and desorption properties of hydrogen gas dissolved in rubbery polymer by utilizing a newly developed volumetric analysis technique. This method was applied to spherical-shaped sealing rubber, such as ethylene propylene diene monomer. The total sorption uptake (C-infinity), total desorbed content (C-0), sorption diffusion coefficient (D-s) and desorption diffusion coefficient (D-d) of hydrogen in rubber are quantified as a function of diameter in both adsorption and desorption processes. No diameter dependence is observed for C-infinity and C-0, whereas D-s and D-d is diameter-dependent. The reversibility between C-infinity and C-0 observed in the process of adsorption and desorption implies the occurrence of physisorption rather than chemisorption by introducing hydrogen molecules. However, the difference between the D-s and D-d values may be ascribed to two different processes. Time to reach equilibrium in both sorption and desorption processes is found to be linearly proportional to the square of sample radius.