Sorption/Desorption of VCM in PVC Selected Food Simulants Systems

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Abstract
Sorption/desorption studies of VCM in the systems PVC/VCM/water, PVC/VCM/corn oil an PVC/VCM/heptane were carried out. At low VCM concentrations, classical curves are obtained, where the sorption isotherms are located below their desorption counterparts. Above a certain VCM concentration a crossover exists and an inversion of the curves occurs. It was suggested that the intersection between the curves represents the point where all the active sites in the polymeric matrix are occupied by monomer molecules. The negative values of the total Gibb's free energy and the energy of mixing in the polymer were found to increase with the decrease in monomer concentration pointing out to the possibility that at low enough monomer concentrations no migration of VCM into the contained food from a PVC package may occur.