EFFECT OF E/P RATIO AND VA CONTENT ON FLOW BEHAVIOR OF EPDM AND EVA BLENDS

The effect of E/P ratio of EPDM rubber and VA content of EVA copolymer on the flow behavior along with the extrudate morphology of EVA and EPDM blends have been studied as a function of shear-rate and processing temperature. High E/P ratio EPDM rubber and low VA content EVA render high viscosities to the blend within the temperature range studied. The same trends hold true for extrudate swell. Stored elastic energy and relaxation time are higher for high E/P ratio EPDM and low VA content EVA. However, compositions with low E / P ratio EPDM exhibit higher shear modulus. At a particular blend composition these rheological parameters show a change in their pattern. Melt fracture occurs to a larger extent for the high E / P ratio EPDM in its blend with low VA content EVA. (C) 1994 John Wiley & Sons, Inc.