Diffusion of organic solvents in a series of ethylene-styrene interpolymers

Information on solubility and diffusivity has been collected for a series of newly developed ethylene-styrene interpolymers. Data were collected using a gravimetric sorption balance, performing differential sorption steps. Experimental results are presented for toluene, ethylbenzene, cyclohexane, n-hexane, and chloroform over a wide range of temperatures and solvent concentrations in the polymer. Comparison between these results and those reported for pure polystyrene indicate good agreement. Thermodynamic equilibrium data were successfully correlated using the Flory-Huggins equation. A comparison of solubility data with estimations using solubility parameters obtained from inverse gas chromatography infinite dilution data failed. The solubility approach consistently underpredicted the measured solubility. The UNIFAC-FV model was applied successfully to accurately predict the solubility for various solvents.; The Vrentas-Duda free-volume theory was applied successfully to correlate the diffusivity behavior. When available infinite dilution data were compared with free-volume estimations. Good agreement between the infinite dilution data and the free-volume estimations were obtained for several systems, while at high temperatures the measured infinite dilution diffusivity values are generally overestimated. From the free-volume regressions the size of a polymer jumping-unit was regressed. A relationship between the polymer composition and the polymer jumping-unit size was established. Knowledge of the polymer jumping-unit size will permit diffusivity predictions for other solvents.; In Chapter 5 an approach is illustrated to utilize 13-C NMR relaxation data to determine polymer free-volume parameters. It is possible to regress Williams-Landel-Ferry parameters, which describe the viscosity-temperature behavior of polymers, from NMR data. An attempt was made to obtain reliable NMR relaxation data for semi-crystalline polymers, where it is not possible to measure the viscosity due to the presence of crystalline regions. This part of the research is still underway, examining the relaxation behavior of polyethylenes of different crystallinity.