The mass transport of ethyl acetate in syndiotactic polystyrene

Abstract

The mass transport of ethyl acetate in syndiotactic polystyrene (sPS) has been studied. Two groups of specimens were prepared using press-cooling and water-quenching. The press-cooled and water-quenched specimens were identified as crystalline and amorphous structures, respectively, by X-ray diffraction. The weight gain of ethyl acetate in sPS was monitored at temperatures from 50°C to 70°C. The crystallinity of a press-cooled specimen prior to solvent sorption was greater than that after solvent sorption. However, solvent-induced crystallization was observed in the water-quenched specimen. The transport of ethyl acetate in both press-cooled and water-quenched specimens was anomalous and consisted of two stages. Each stage of the sorption curves was well fitted with Harmon's model. Both the diffusion coefficient and velocity component satisfy Arrhenius behavior. For the press-cooled specimen, fluxes of Case I and Case II transport flow from the outer surface to the center, but for the water-quenched specimen, the solvent is squeezed out. Pure Case II transport did not appear in the water-quenched specimen.