Two volumetric techniques for determining the transport properties of hydrogen gas in polymer

We report two different volumetric analysis techniques to determine the transport properties of hydrogen dissolved in rubbery polymers. This measures the volume filled by the released hydrogen from rubber by gas collection in a graduated cylinder and by gas chromatography after exposure a sample with high-pressure hydrogen and decompression. From the measurement results, the uptake (C∞), diffusion coefficient (D), and solubility (S) of hydrogen are quantified by employing an upgraded diffusion analysis program. These methods are applied to three cylindrical rubber samples. Dual adsorption behaviors with increasing pressure are observed for all rubber samples. C∞ follows Henry's law up to ∼15 MPa, whereas the Langmuir model applies up to 90 MPa. No size dependence are observed for C∞ and S, whereas pressure-dependent D shows Knudsen and bulk diffusion behavior below and above a critical pressure, respectively. The S and D measured in two techniques are consistent with each other within the expanded uncertainty evaluated. A COMSOL simulation is compared with experimental investigations.