Cosolvent effects in polymer-solvent systems

Devolatilization of polymers is important to industrial applications such as film drying, foam production, microelectronics manufacturing, and bulk plastics processing. The mass transport and thermodynamics within such systems often limits production throughput. For example, a common method of foam devolatilization is ambient pressure desorption. In this situation, the diffusion of residual species from the foam to the surrounding air is the limiting step in the manufacturing process. Therefore, the use of a cosolvent to affect the solubility and diffusion favorably is an area of interest to industry. However, little data exist and few models are capable of predicting the influences that occur when a cosolvent is added to a system.; This thesis focuses on measuring and describing cosolvent effects in polymer-solvent systems. Inverse gas chromatography was used to test the influence of CO2 and ethylene at high pressures on the solubility and diffusion of several solvents in poly(vinyl acetate) and poly(styrene). Through testing at multiple conditions it was possible to determine which gas had the largest effect on the polymer-solvent behavior. In addition, influences due to solvent size were examined.; A ternary experiment was designed to probe the effect of water on the solubility and diffusivity in a poly(ethylene)-ethylene system. The experiment is a simple gravimetric technique for measuring mass uptake of penetrants in polymers.; Lastly, several thermodynamic models are applied to a phase equilibria problem of predicting anomalous solubility behavior in copolymer systems. In certain systems, solvents have been observed to have higher solubility in copolymers compared to the two respective homopolymers. The goal was to determine which, if any, models could predict such behavior without experimental data for parameterization.