AbstractRheological behavior of neoprene and acrylic rubbers and their carbon blackfilled compounds has been studied using a Monsanto Processability Tester. These systems show pseudoplastic flow behavior. Die swell increases with increase in shear rate up to a limit beyond which it decreases. It also decreases with increase in filler loading and temperature. The maximum recoverable deformation has been calculated by assuming that the viscous response of the rubbers obeys the power law model and elastic behavior is described by Hooke's law and has been correlated with die swell. A linear generalized relationship has been obtained between the die swell and the recoverable deformation. The principal normal stress difference has been found to increase nonlinearly with shear stress. Activation energy of melt flow process increases with increase in shear rate up to a limit, after which it decreases for acrylic rubber and 10 phr filled neoprene rubber.