Carbon—Silica Dual Phase Filler, A New Generation Reinforcing Agent for Rubber: Part VIII. Surface Characterization by IGC

The surface characteristics of carbon-silica dual phase filler (CSDPF) were investigated by inverse gas chromatography (IGC) at infinite dilution. It was found that due to its unique surface microstructure, the dispersive component of the surface energy γ s d of CSDPF is considerably higher than those of carbon black and silica. Among CSDPFs, the surface energies increase with increasing surface area. The adsorption energies of a series of hydrocarbon probes and polar compounds were also measured with IGC. Relative to conventional fillers, the higher adsorption energies of hydrocarbon probes on dual phase fillers as well as their higher γ s d , suggest a stronger interaction with hydrocarbon polymers. This is consistent with observations on bound rubber measurement. The overall polarity of CSDPF and the specific or polar component of the surface energy of CSDPF were estimated from specific free energies of adsorption of polar compounds. The polarity of this new filler, while being similar to that of its carbon black counterpart, is substantially lower than the polarity of precipitated silica. This would result in a high compatibility of this dual phase filler with hydrocarbon rubber, leading to lower filler-filler interaction and better microdispersion.