AbstractAccurate solubility limits of polymers are best expressed by molecular weight fractionation curves. Individual curves may be obtained for each polymer–solvent (–nonsolvent) system. A method for predicting solubility behavior, based on solubility parameter δ and hydrogen bonding index γ, is proposed here. The correlation is of the formdocumentclass{article}pagestyle{empty}begin{document}$lefteta right = kfrac{{T^{left( {cQ} right)} }}{{left( {v.f} right)^{left( {ab + R} right)} }}$end{document}where η = intrinsic viscosity of precipitated polymer;T= absolute temperature; (v.f.) = volume fraction of solvent;R= (δs− δn) − 0.3(γs− γn);Q= (γp− γe)2.2/(δp− δe);prefers to polymer;srefers to solvent;nrefers to nonsolvent;erefers to solvent system at theta temperature; anda,b,c, andkare fitted constants. The correlation was derived from data for poly(vinylpyrrolidone) and polyacrylamide. It probably is limited to systems in which the precip
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