Sorption of propane and propylene in polyethylene

Measurements are reported of the solubility and concentration of propane and propylene in polyethylene, at temperatures from ?30°C to +30°C and pressures from 1.68 to 3.52 atm. Solubility of both gases in polymer depends on penetrant activity. Henry's law is not obeyed at high values of the penetrant activity, i.e., in the vicinity of the condensation point of the gas. The interaction between the solvent and the polymer is independent of pressure and a function of temperature. The propylene-polyethylene interaction seems to reach a maximum at 10°C within the range investigated. A physical mechanism, based on opposite effects of temperature upon polymer and penetrant, is suggested to explain the results.