VAPOR-LIQUID-EQUILIBRIA OF COPOLYMER PLUS SOLVENT AND HOMOPOLYMER PLUS SOLVENT BINARIES - NEW EXPERIMENTAL-DATA AND THEIR CORRELATION

Sixty-four isothermal data sets for vapor-liquid equilibria (VLE) for polymer + solvent binaries have been obtained using a gravimetric sorption technique, in the range 23,5-80 degrees C. Solvents studied were acetone, acetonitrile, 1-butanol, 1,2-dichloroethane, chloroform, cyclohexane, hexane, methanol, octane, pentane, and toluene. Copolymers studied were poly(acrylonitrile-co-butadiene), poly(styrene-co-acrylonitrile), poly(styrene-co-butadiene), poly(styrene-co-butyl methacrylate), poly(vinyl acetate-co-ethylene), and poly(vinyl acetate-co-vinyl chloride). All copolymers were random copolymers. Some homopolymers were also studied: polyacrylonitrile, polybutadiene, poly(butyl methacrylate), poly(ethylene oxide), polystyrene, and poly(vinyl acetate). The composition of the copolymer may have a surprising effect on VLE. Normally, deviation from ideal behavior lies between those of the constituent homopolymers, according to the copolymer composition, as observed for cyclohexane + poly(ethylene-co-vinyl acetate) and chloroform + poly(styrene-co-butyl methacrylate). However, the strong nonideal behavior observed for systems containing hydrocarbons and poly(butadiene-co-acrylonitrile) shows that the effect of acrylonitrile is in excess of that expected from the copolymer composition. The perturbed hard-sphere chain (PHSC) equation of state was used to represent VLE of the copolymer solutions studied here.