CONCENTRATION-DEPENDENCE ON VISCOSITY OF OLIGOURETHANE DIOLS

To obtain viscosity suitable for application, relatively low molecular weight polymers, i.e., oligomers, are used in the formulation of high solids coatings. To support this requirement, the concentration depen dence of the viscosity of synthesized oligourethane diols in different solvents was analyzed using Erickson's models. By regression analysis , it was found that the correlation coefficients are fairly good and t he plots of the residuals are more random. The weight intrinsic viscos ity, [eta(w)], composed of the oligomer component, O-[n]w, and the oli gomer-solvent interaction component, I-[n]w, was calculated from the i ntercept of the plot of 1/ln eta(r) vs. 1/w(0). The parameter I-[eta]w , related to the solvent molar volume and the distance between the oli gomer and solvent partial cohesion parameter coordinates, indicates th e degree of interaction between the oligomer and solvent. The partial cohesion parameters of the oligomers obtained by the group-contributio n method were used for calculating the interaction component of oligou rethane diols. (C) 1997 John Wiley & Sons, Inc.