A VISCOMETRIC STUDY OF THE MISCIBILITY BEHAVIOR OF POLY(N-VINYL PYRROLIDONE) BLENDS

The miscibility behaviour of blends of poly(N-vinyl pyrrolidone) (PVP) with poly(vinyl chloride) (PVC), poly(vinyl acetate) (PVAc) and vinyl chloride-vinyl acetate (VCVAc) copolymer has been investigated on the basis of a viscometric approach. PVP is found to be miscible with PVC over the entire composition range, as is evident from the high values observed for the intrinsic viscosity of transfer. This is further sup ported by the single glass transition temperature observed in differen tial scanning calorimetry studies of the blend films. Blends of PVP wi th VCVAc copolymer exhibit microphase separation which is shown clearl y in the scanning electron micrographs of the films. PVAc/PVP blends s how interaction only at low PVAc contents, but in general are immiscib le.