A new method for quantification of the phase selective localization of hybrid fillers in rubber blends

A new method for the quantitative description of the phase-specific localization of hybrid fillers in rubber blends was developed based on the wetting concept. Using the new concept, the kinetics of phase-specific localization of silica (Si)/carbon black (CB) hybrid fillers in styrene-butadiene rubber (SBR)/natural rubber (NR) blends was experimentally characterized during the single-step mixing and the multi-step mixing process. It could point out that the localization of the hybrid fillers at the end of the mixing process always reaches the stationary stage regardless of the mixing regime. The stationary state of filler localization is related to the migration of silica and CB during the mixing process, determined by the thermodynamic driving forces and well predicted by the Z model. The adsorption of the curing additives on the filler surface markedly alters the surface energy of silica and CB, which in turn influences the localization of hybrid fillers in rubber blends, particularly at low filler loading. That is why the morphological investigation made by electron microscopy for low filled rubber blends can hardly be applied to describe the filler localization of hybrid fillers in rubber blends at high filler loading.

Automated summary

A new method based on the wetting concept was developed for the quantitative description of the phase-specific localization of hybrid fillers in rubber blends. Experimental results show that the localization of fillers reaches a stationary stage during the mixing process, regardless of the mixing regime, and is related to thermodynamic driving forces.