Abstract: | Various methods of determining polymeric molecular compatibility were applied to blends of poly(vinyl chloride) (PVC) and poly(ethylene-co-vinyl acetate-co-sulfur dioxide) (E/VA/SO2). In one series, where the E/VA/SO2 had a mole composition of 72.7/18.5/8.8, true compatible blends were demonstrated by phase-contrast microscopy, torsion pendulum studies, and differential scanning calorimetry experiments for blends containing up to 40% E/VA/SO2. These blends exhibited a single Tg whose compositional variation was found to follow the Fox expression. Experimental densities were slightly greater than predicted on assuming volume additivity. This observation implies better packing and a negative heat of mixing and thus is in harmony with a negative free energy of mixing and the observed molecular compatibility. |