Utilization of new micronized and nano-CoO·MgO/kaolin mixed pigments in improving the properties of styrene–butadiene rubber composites

The present work highlights the role of a new prepared core–shell pigment based on kaolin as the bulk (core) covered with cobalt oxide and magnesium oxide comprising the surface of the pigment (shell). The new pigment was prepared in the micronized and nano-sized particles and its effect on the different properties of styrene–butadiene rubber (SBR) vulcanizates was studied. Incorporation of these two particle sized pigments and their varied content of cobalt oxide to magnesium oxide in the shell of the different pigments in different styrene–butadiene rubber vulcanizates was done, and their effects on the rheological, physical, mechanical and dielectric properties was studied. The study showed that there was a significant effect of these new pigments on SBR properties, and that the optimum micronized pigment loading in SBR was 30 phr, while that of the nano-pigment was 6 phr. The different measured properties were in good agreement with each other.