Plasticization of amorphous polystyrene by volatile organic compounds

The plasticizing effect of 4 model volatile compounds (n-hexane, toluene, p-xylene, and ethylbenzene), able to be sorbed on polystyrene (PS) was studied. A large weight fraction range was investigated (up to 0.35) using differential scanning calorimetry. Mathematical modeling, using Fox, Kelly-Bueche, Chow and Gordon-Taylor models, was performed to model the behavior of the glass transition temperature of PS after VOC sorption. A strong plasticization of PS was evidenced by a significant reduction in the glass transition temperature of the binary mixtures (T-gm). Among the four studied molecules, the linear one, n-hexane, displayed a better plasticizing efficiency than the aromatic ones, which lay in the same range. Indeed, a 15 % (w w(-1)) n-hexane content in PS decreased the T-gm by 84 K. The Gordon-Taylor model was the best model to fit the experimental data for all the volatile organic compounds tested. [GRAPHICS] .