| Abstract: | Phase diagrams including tie lines for nine ternary solvent–polymer–polymer systems have been obtained using size exclusion chromatography. The systems studied were toluene–polystyrene (PS)–isoprene rubber (IR), toluene–PS–butadiene rubber (BR), cyclohexane–PS–BR, tetrahydrofuran(THF)–PS–poly(methyl methacrylate) (PMMA), and THF–PS–poly(butyl methacrylate) (PBMA) at temperatures between 30 and 75°C. The results indicate PS-PMMA is less compatible than PS-PBMA in the presence of THF. Also, the combination of trans- and 3,4–IR-PS is less compatible than cis–IR-PS in the presence of toluene. The original Flory–Huggins model for ternary systems has been modified to account for the concentration dependence of the interaction parameters. The modified Flory–Huggins model consists of two interaction parameters per binary. Using this model, six parameters have been regressed for each of the experimental systems studied. Although the parameters are not physically meaningful, the model and the parameters obtained using it are useful for correlating the experimental phase diagrams. The results obtained using the modified six parameter model are shown to be superior to those obtained using the original three parameter model. © 1993 John Wiley & Sons, Inc. |
