Measurement and correlation of sorption and transport properties of ethylene-propylene-diene monomer (EPDM) elastomers

The diffusivity and solubility of argon, methane, oxygen, and carbon dioxide in two EPDM-based polymers, one formulated with 34 wt% carbon black and the other formulated without carbon black, have been measured at 20 °C and at a range of pressures up to 266.448 × 102 Pa (2000 Torr). A linear relationship was observed between the amount sorbed and pressure for all gases, indicative of Henry's law behavior. The uptake kinetic measurements were well represented by a Fickian diffusion model and the resulting diffusivity was found to be independent of pressure. Analysis of solubility data revealed that the carbon black filler appeared to uptake negligible quantities of gas. The observed effect of non-porous filler on diffusivity and permeability was compared with Maxwell theory prediction and fell within experimental error. The experimental results were used to assess the applicability of a corresponding-states based correlation for predicting gas diffusivity and solubility in polymers. This correlation was found to adequately represent an order of magnitude estimate of the data for all gases, allowing estimates to be made for other gases not considered in this investigation.