Effect of Oil and Black on SBR Rheological Properties

Abstract

Abstract Effects of a naphthenic oil and of HAF carbon black on SBR processability were evaluated. Three rheological parameters related to processability are apparent viscosity, extrudate swell and extrudate surface roughness; they were studied with a capillary rheometer over a shear rate range of 10 to 3000 sec−1. This instrument is particularly useful because processability can be evaluated at industrial processing conditions. At constant shear rate an increase in oil level in the compound decreases viscosity, decreases swell, and reduces the shear stress range over which a smooth extrudate can be obtained. An increase in black level increases viscosity, decreases swell, and extends the range over which a smooth extrudate can be obtained. The opposing effects which oil and black have on processability demonstrate that an optimum combination of these two components exist. To best utilize the rubber process oil and carbon black the optimum processable compound must be selected. Such a selection is illustrated by the use of contour graph analysis of the data.