Mixtures of PET and PVC were prepared in three different compositions by a solution blending technique. A plasma surface modification method was applied to PET powder surfaces in order to enhance the miscibility of both components because of their mutual insolubility. The intrinsic viscosities of blends were measured in a phenol/tetrachloroethane-mixed solvent system. The degree of compatibility of blends was characterized by the use of the parameter DELTAb, as derived by Krigbaum and Wall. (C) 1993 John Wiley & Sons, Inc.