Rheological Properties of Rubber-Carbon Black and Carbon Black-Oil Compounds Including Measurements at Very Low Shear Stresses

Abstract

The rheological properties of binary rubber-carbon black compounds at compositions 5, 20, 30, 40 and 50 volume percent carbon black have been investigated as well as ternary compounds with rubber/carbon black/oil compositions of 70/20/10, 60/20/20 and 50/20/30, respectively. The compounds were investigated using (1) a constant stress creep instrument at very low rates of deformation, (2) a rotational rheometer at intermediate shear rates and (3) a capillary extrusion instrument at higher shear rates. In experiment (1), it was found that below a critical yield stress, the strain becomes saturated and finite. Above this stress the strain becomes unbounded and the compound maintained a steady shear flow. This observation was made for all compounds investigated. The values of the yield stresses obtained using the creep instrument were found to be significantly lower than those obtained from common extrapolations from rotational and capillary rheometers. In the ternary compounds it was also observed that as the oil content increases, not only the viscosity but the yield stress is reduced significantly. This observation is important because it can throw light on the type of interactions between carbon black and the rubber matrix.

X-ray absorption, particle orientation, and rheological behavior of talc-calcite mixed-particle compounds in a polystyrene matrix

“…Figures 10 and 11 for the talc-filled compound system and Figures 12 and 13 for the calcite-filled system showed that shear viscosity increases with increasing the particle loadings, and the shear viscosity increases with decreasing the shear rate, as noted by various other studies on PS-CaCO 3 compounds. 5,7 As the shear stress decreases to very low levels, the shear viscosity was found to exhibit a plateau, as had been previously observed in our laboratories by Osanaiye et al 31 and Araki and White. 32 At still lower shear stresses, many of the compounds exhibit yield stresses.…”

“…33 They used creep measurements. Apparent yield values significantly overestimated true values, as pointed out by Osanaiye et al 31 They carried out creep experiments of a carbon black-filled ethylene-propylene terpolymer (EPDM) at 100°C using sandwich viscometer at very low shear stress. The talc particle-filled system exhibits higher yield values compared to the calcitefilled system.…”

“…They have similar values to our "threshold" yield values. Exceptions are the work of Osanaiye et al, 31 Araki and White, 32 and Li and White. 33 They used creep measurements.…”

Linear and nonlinear viscoelasticity of carbon black filled elastomers: Use of complementary rheological characterizations

“…This is associated with significant changes in the rheological properties, particularly with a yield behavior well documented for highly filled elastomers in earlier works (e.g., ref. 6). In this study, we focused on the fluidlike behavior of elastomer compounds, selecting carbon black volume fractions below 0.15 so that no yield behavior would be expected.…”

Shear viscosity of carbon black filled polypropylene at very low shear stresses

“…It was primarily used in the creep mode. Weight compensation of the inner member (22,23) was considered but was not used a t 180°C. The shear stresses were calculated from…”