EVALUATION OF SOLVENT RESISTIVITY OF FLUOROPOLYMERS FOR USE AS BACKUPMEMBRANES IN ISOCYANATE SAMPLERS

Four types of fluoroelastomer (VITON) membranes were tested for their resistivity toward dimethyl sulfoxide, dioxane, and toluene at 25, 45, and 60 degrees C, using a gravimetric method. Coefficients of diffusi on and permeation were calculated from the sorption results. Analytica l solutions of Fick's equation as well as a numerical method were used to calculate the concentration profiles of liquids in the membrane ma terials at different penetration depths and exposure times. Activation parameters for diffusion, permeation, and sorption were obtained from the Arrhenius equation. These membrane materials were evaluated for t heir ability to serve as a barrier to solvent permeation in a composit e membrane sampler for the analytical determination of isocyanates gen erated during spray-painting operations. (C) 1996 John Wiley & Sons, I nc.