Studies on miscibility of poly(vinyl chloride) with natural rubber-graft-polyacrylonitrile and natural rubber-graft-poly(methyl methacrylate)

The miscibility of poly(vinyl chloride)/natural rubber-graft-polyacrylonitrile (PVC/NRPACN) and PVC/NR-graft-poly(methyl methacrylate) (PMMA) were studied by differential scanning calorimetry (DSC) and viscometry. DSC curves of PVC/NR graft copolymer blends showed a major endotherm at about 265 degrees C that was assigned to the thermal decomposition of PVC. PVC/NRPMMA blends showed a minor endothermic peak at about 124 degrees C and the PVC/NRPACN blends showed a broad peak (which develops into two peaks) at about 160 degrees-180 degrees C, respectively. Absolute viscosity versus weight percent PVC plots of the two sets of blends were nonlinear. X-ray diffraction patterns of the PVC/NRPACN blends showed overlapping spacings due to the constituent polymers. Phase-contrast micrographs of the PVC/NRPACN blends showed gross phase discontinuity. The heats of mixing solutions of PVC blended with NRPMMA were found to be well above the upper limit of miscibility. (C) 1996 John Wiley & Sons, Inc.