Two‐component polymer systems: Physical properties as related to compatibility and interaction

The physical properties of mechanical blends of poly (vinyl chloride) (PVC) with ethylene‐vinyl acetate copolymers (EVA) and with acrylonitrile‐butadiene copolymers (NBR) have been studied using light scattering. gas permeability, density, and dynamic‐mechanical (loss tangent) measurements for thin films. The data show that the PVC/EVA blends are not compatible at 45% VAc content in EVA. A “phase inversion” is indicated at 5‐7 wt‐% EVA. EVA containing 65% VAc interacts more with the PVC component and shows no indication of phase inversion. A mixed phase of PVC/EVA‐65 is formed with higher measured density than calculated, assuming additivity. NBR containing increasing amounts of AN (21.7, 29.6, and 41.6 wt‐%) shows increasing compatibility with PVC due to interaction. For 50:50 blends of PVC/NBR the measured densities are 0.033, 0.050, and 0.053 g/ml higher than the calculated values for the three NBR samples. There are some indications of a phase inversion at NBR contents of 5‐7 wt‐%.