Sorption and diffusion profiles of monocyclic aromatic liquids into polymeric blends of ethylene-propylene random copolymer and isotactic polypropylene

Molecular transport of monocyclic aromatics into polymeric blends of ethylene-propylene random copolymer and isotactic polypropylene is investigated in the temperature interval 25 degrees-70 degrees C. For all liquids, the penetrant transport rate, equilibrium penetrant uptake, and degree of penetrant overshoot are influenced by the type of the penetrant and the experimental temperature. Sorption-desorption-resorption-redesorption (S-D-RS-RD) experiments have been performed to determine the true equilibrium sorption and diffusion coefficients. These S-D-RS-RD experiments are a convenient method of determining the continuous weight loss during long-term solvent exposure, a phenomenon associated with the release of residuals. The molar mass between crosslinks of the polymer, the kinetic rate constants, and the activation parameters for diffusion, permeation, and sorption are obtained. Transport coefficients and the activation parameters are affected by the type and size of the penetrant molecules. The sorption kinetic results indicate that the transport is of the anomalous type.