Solubility and transport of gases in nylon and polyethylene

Solubility isotherms for He, H2, Ne, N2, Ar and CO2 have been determined over the temperature range 273·2K to 333·2K in Nylon 11 and polyethylene both indirectly, from time-lags and permeabilities, and also directly. For the 100% amorphous polymer at 298·2K solubility coefficients, σ, approximate to the relations: log σ=−2·03+0·0093ε/k (polyethylene)log σ=−2·41+0·0111ε/k (Nylon 11) where εk is the Lennard-Jones interaction parameter for the gas. Heats of solution in polyethylene were endothermic for all the gases except CO2 and in Nylon 11 for all except Ar and CO2. Nylon was considerably more permselective to helium than polyethylene and energies of activation for diffusion were somewhat larger and more sensitive to molecular dimensions than in polyethylene.