Acrylic Rubber/Nitrile Rubber Blends: The Effect of Curatives on the Mechanical, Morphological, and Dynamic Mechanical Properties

The Curing characteristics and mechanical properties of blends constituted by acrylic rubber (ACM) and nitrile rubber (NBR) were investigated. The Curing process was performed by a combination of curing systems specific for each rubber component. The curing system for the ACM phase consisted of hexamethylene diamine carbamate/sodium stearate, whereas the NBR phase was cured with different systems: accelerated Sulfur or bismaleimide/peroxide. In all of the curing systems employed, the blends presented more outstanding ultimate tensile properties than the individual rubbers, which indicated a compatibilization effect of the Curing systems. Dynamic mechanical analysis of the blends revealed a broadening of tan delta peak and a shift in the glass-transition temperature of the ACM phase in the direction of the NBR transition in most of the systems studied and an increase in the storage modulus, which was also an indication of a compatibilization effect. Scanning electron microscopy also revealed a very thin rubber phase, which confirmed the compatibilization. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 721-729, 2009