Molecular simulation of transport behavior of hydrogen and hydrogen isotopes in brominated butyl rubber

Molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) method were used to study the diffusion and the solubility coefficients of H2, D2, T2 in brominated butyl rubber (BIIR). Using the free volume theory, the mechanism of the diffusion of small molecules in brominated butyl rubber was discussed, and the trajectory of gas motion was obtained. It was shown that in terms of hydrogen and hydrogen isotopes, the smaller the mass was and the faster the kinematic velocity was, the higher the diffusion coefficient was. The solubility coefficients of H2, D2, T2 were close. Moreover, the permeability coefficients obtained by the simulation were in good agreement with the experimental data. They provided some theoretical basis for improving the barrier properties of materials, simultaneously the fact that tritium also had good barrier properties to vulcanized brominated butyl rubber was forcasted.