The Sorption, Diffusion, and Permeation of Vapors of Low Molecular Weight Hydrocarbon in Undrawn, Polyolefin Film.

Abstract

Investigation has been made of the sorption, diffusion, permeation of iso-pentane, n-pentane, n-hexane, and n-heptane in undrawn low-density polyethylene and polypropylene in the temperature range between 26°C-60°C The permeability coefficient at the highest activity was in the order of 10-10mol-cm/cm²-sec at 30°C under the saturated vapor pressure difference, and decreased in the order of n-pentane, iso-pentane, n-hexane and n-heptane, whereas the solubility coefficient increased in the same order. The activation energy for the diffu. sion of n-heptane at the highest concentration was only about 3 Kcal/mole in polyethylene, indicating that in these systems polymer films are highly swollen. It was concluded that the diffusvity controlled the permeability in polyolef in film-low molecular weight hydrocarbon system.