Hydrogen gas permeation in peroxide‐crosslinked ethylene propylene diene monomer polymer composites with carbon black and silica fillers

Abstract This study investigated the effect of two types of fillers, carbon black (CB) and silica, on the H 2 permeation of peroxide‐crosslinked ethylene propylene diene monomer (EPDM) polymers at different pressures (1.2–9.0 MPa). The H 2 uptake was linearly correlated with the exposure pressure in all specimens. The H 2 solubility in the filled EPDM composites also increased linearly with an increase in the filler content. The H 2 solubility was determined by the absorption of polymer networks and adsorption at the filler surface in the CB‐filled EPDM. Meanwhile, the H 2 solubility in neat and silica‐filled EPDM was dominated by the polymer network absorption. In the filled EPDM, H 2 diffusivity decreased because the filler increased the tortuosity of the polymer. The effects of filler on H 2 permeation were largest in the high‐abrasion and semi‐reinforcing furnaces, while the effects were lowest in the silica filler. This trend was associated with the surface area and interface of the fillers. The correlations of the average diffusivity (or permeability) with the filler content and crosslink density of the composites were observed and discussed. From the resulting relationships, we can predict the H 2 permeation properties of the compounded EPDM candidates, when used as seal materials, under high‐pressure environment in H 2 ‐refueling stations.