Evaluation of hydrogen permeation characteristics in rubbery polymers

To find suitable sealing material with low permeability against hydrogen, the elaborated evaluation techniques for hydrogen transport properties are necessary. We developed two techniques determining the permeability of hydrogen including software for diffusion behavior analysis. The techniques contain gas chromatography and volumetric collection of hydrogen gas. By measuring the hydrogen released from polymer samples with respect to the elapsed time after being decompressed from the high pressure, total amount of adsorption and diffusivity (D) of hydrogen are evaluated with self-developed program of Fick's diffusion equation specified to a sample shape. The solubility (S) and permeability (P) of the polymers are determined through Henry's law and a relation ofP=SD, respectively. Developed techniques were applied to three kinds of spherical-shaped sealing rubbers, NBR, EPDM, and FKM. The D, S and P have been measured as function of pressure. The permeability obtained by both methods are discussed with Comsol simulation. The measuring procedures of the permeability properties of hydrogen. (a) Heat treatment, (b) charging hydrogen in high pressure chamber, and the amount of hydrogen released is measured using (c) TDA-GC, or (d) VC methods. [Display omitted] •Development of two techniques for measuring permeation characteristics of hydrogen gas for three rubbers.•Total charging amount (C0) and diffusivity(D) are obtained, which evaluate solubility(S) and permeability(P).•Pressure dependence on C0 in three rubbers follows Henry's law.•S measured in two methods are consistent.•Differences in D through water and air are explained by Comsol simulation.