STUDIES ON MISCIBILITY OF BLENDS OF POLY(ETHYLENE-CO-METHYL ACRYLATE) AND POLY(DIMETHYL SILOXANE) RUBBER BY MELT RHEOLOGY

Rheological studies of the blends of poly(ethylene-co-methyl acrylate) (EMA) and poly(dimethyl siloxane) (PDMS) rubber have been carried out at various temperatures and different shear rates by a Monsanto processability tester. The melt viscosities of the blends are found to be higher than that calculated as per the additivity rule, showing a positive deviation, an indication of synergism present in the blends during melt processing. This confirms our earlier finding that the blends are miscible throughout the composition range. The activation energy of flow of the blends are always higher than that calculated as per the additivity rule. The comparatively higher activation energy for the 30:70 EMA-PDMS rubber blend among the systems studied confirms our earlier finding that extent of reaction between EMA and PDMS rubber is significantly higher at this proportion of the blends studied. This substantiates the miscibility between blends of EMA and PDMS rubber throughout the composition range. (C) 1995 John Wiley and Sons, Inc.