Property modellingTime-resolved statistics of cavity fields nucleated in a gas-exposed rubber under variable decompression conditions - Support to a relevant modeling framework

Rubbers exposed to high-pressure diffusive gas are known to undergo cavitation during decompression, when the expansion of the adsorbed gas occurs faster than desorption out of the material. This phenomenon has been qualitatively depicted in the literature but quantitative data is lacking, especially to support accurate modeling. A time-resolved statistical analysis of cavity fields was applied to an un-filled EPDM exposed to hydrogen. It was based on a covariogram method, applied to successive pictures taken all along decompression tests. It allowed quantifying the influence of decompression parameters (decompression rate and pressure for saturation) on the number, average size and size distribution of cavities. The relevance of modeling based on a unit cell containing one or two cavities was discussed, and the size/isotropy of this Representative Elementary Volume could be defined. The limitation of such modeling was evidenced under more drastic decompression conditions, due to interaction effect between close cavities.