Effect of Carbon Black on the Rheological Properties of Styrene N-Butyl Methacrylate Copolymer Melt

Abstract

Carbon black reinforcement in elastomers, as well as glassy polymers, has been the subject of an intense study for almost fifty years.¹ Grades of carbon black are distinguished by surface area and bulkiness (dibutyl phthalate absorption), the latter being a function of the number and arrangement of particles within an aggregate. Carbon black surface area increase results in an increase in the elastic modulus at low amplitude of deformation because of the presence of interaggregate network.² At higher amplitudes of deformation, there is breakage and reformation of this network. Aggregate bulkiness increases both the elastic and the viscous modulus without changing their ratios.³ Lobe and White⁴ have recently observed that rheological behavior of a molten filled polymer at 10–20% loading is that of a gel. They also found that viscosity does not level off at decreasing rates of deformation but continues to increase.