Effects of Solvent Molecular Structure on Diffusion through Plasticized Poly(vinyl chloride) Films

Diffusion of organic solvents in plasticized poly­(vinyl chloride) (PVC) films is industrially significant for inkjet-printed PVC graphic displays, but comprehensive research on the mechanism of solvent diffusion in such systems is lacking. This study employs two easy-to-implement experimental techniques for diffusion measurement and reports on both the steady-state and non-steady-state diffusivities of 20 industrially relevant organic solvents, spanning five chemical moieties, in a commercial PVC base film. To better understand the trends in diffusivity values with solvent properties, the diffusivity was compared to multiple kinetic mobility and thermodynamic diffusion models. Kinetic mobility parameters representing molecular size and shape were found to be good predictors of diffusivity in this study. In contrast, the thermodynamic Hansen solubility parameters from the solvent and PVC were shown to be a less robust predictor of the diffusivities. Molecular weight, van der Waals volume, and vapor pressure were identified as the best performing predictors that also have distinct merits for guiding industrial practices and furthering theoretical understandings. Ultimately, the results from this study are useful in predicting the performance of solvents for industrial inkjet printing and in understanding the underlying microscopic transport mechanisms.