MORPHOLOGY, MECHANICAL AND VISCOELASTIC BEHAVIOR OF BLENDS OF NITRILERUBBER AND ETHYLENE-VINYL ACETATE COPOLYMER

Nitrile rubber/ethylene-vinyl acetate copolymer (NBR/EVA) blends with different ratios were prepared by using a two roll mixing mill. The mo rphology of the blends was studied using optical and electron microsco pies. The morphology of the blends indicated a two phase structure in which the minor phase is dispersed as domains in the major continuous phase. However, between 40 and 50 wt% of NBR content both NBR and EVA exist as continuous phases and generate a co-continuous morphology. Th e viscoelastic properties have been determined using a Rheovibron Visc oelastometer at 35 Hz over a wide range of temperatures. The effect of blend ratio on the mechanical properties such as tensile strength, el ongation at break, stress-strain behaviour and hardness has been inves tigated. The mechanical properties increase with the increase of EVA c ontent in the blend. Attempts have been made to correlate the Variatio n of properties with morphology of the blend. Various composite models have been used to fit experimental mechanical and viscoelastic data.