The effect of styrene grafting on the diffusion and solubility of organic liquids in polyethylene

The effect of grafting styrene onto low‐density polyethylene on the diffusion and solubility of benzene and n‐hexane in the graft copolymer has been investigated. The diffusion coefficient at zero concentration Dc = 0 for both benzene and n‐hexane decreased with the amount of styrene grafting in the polyethylene–styrene graft copolymer membrane. The free volume parameters of the polyethylene–styrene graft copolymer were calculated using benzene and n‐hexane as the diffusing species. Results show that there is a large decrease in free volume as grafting proceeds and the effect is more pronounced at low levels of grafting. Solubility was found to be a function of the per cent grafting, there being a 50%–90% increase in benzene solubility in a 26% graft compared to polyethylene. The increase in solubility for n‐hexane was considerably lower. The effect of crystallinity on the free volume parameters has also been calculated.