FLOW VISUALIZATION OF THE INFLUENCE OF COMPATIBILIZING AGENTS ON THE MIXING OF ELASTOMER BLENDS AND THE EFFECT ON PHASE MORPHOLOGY

The effect of several different potential compatibilizing agents on the rate of mixing and phase morphologies of immiscible blends of ethylene propylene (EPM) and acrylonitrile-butadiene (NBR) copolymers of varying nitrile content is described. Flow visualization investigations using an internal mixer with glass windows have been used to show that these agents increase the rate of homogenization of EPM-NBR blends. A scanning electron microscopy (SEM) study on the morphology of the EPM-NBR blends shows that the choice of a suitable compatibilizing agent results in a final dispersion of NBR particles inside the EPM phase with an average size even as low as 0.5 to 1-mu-m. Chlorinated polyethylene (CM) has been found to be the most effective in increasing mixing rate and reducing the scales of morphology. However, for NBRs with low acrylonitrile concentration, chlorosulfonated polyethylene (CSM), polychloroprene (CR), hydrogenated nitrile (HNBR), and polybutadiene (BR) were also found to act as suitable compatibilizing agents.