MORPHOLOGY AND MECHANICAL-PROPERTIES OF THERMOPLASTIC ELASTOMERS FROMNYLON-NITRILE RUBBER BLENDS

Nylon-nitrile rubber blends having different plastic-rubber component ratios (100/0, 80/20, 70/30, 60/40, 50/50, 40/60, 30/70, 20/80, and 0/ 100) were prepared by melt mixing technique in a Rheocord-90 at a temp erature set at 180 degrees C. The mixing characteristics of the blends have been analyzed from the rheographs. The morphology of the blend w as studied using optical and electron microscopies, with special refer ence to the effect of blend ratio. The micrographs indicate a two-phas e system where the component having lower proportions was found to dis perse in the major continuous phase. A cocontinuous morphology was obs erved for 50/50 composition. Mechanical properties of the blends have been measured according to standard test methods. The effect of blend ratio on the mechanical properties like tensile strength, tear strengt h, elongation at break, stress-strain behavior, and hardness has been analyzed. The influence of the strain rate on the mechanical propertie s has also been analyzed. The mechanical properties were found to have a strong dependence on the amount of nylon in the blend. It is found that the blends with higher proportions of nylon have superior mechani cal properties. The observed changes in mechanical properties are expl ained on the basis of the morphology of the blend. Various theoretical models such as Series, Parallel, Halpin-Tsai, and Coran's equations h ave been used to fit the experimental mechanical data. (C) 1996 John W iley & Sons, Inc.