In situ shear-induced mercapto group-activated graphite nanoplatelets for fabricating mechanically strong and thermally conductive elastomer composites for thermal management applications

Interfacial interaction is one of the most crucial and dominant factors affecting the performance and behavior of a material. The surfaces of layered expanded graphite (EG) were activated by covalently grafted mercapto groups (-SH), which can readily react with the macromolecular chains of rubber, thus forming a strong interfacial adhesion between the filler and the rubber matrix. Shear-induced mercapto-group-activated graphite nanoplatelets (S@GNPs) were fabricated in situ by compound mixing in a two-roll mill. A correlation between the interfacial interaction and the thermal conductivity, as well as the thermo-physical properties, was comprehensively investigated. The results showed that rubber/S@GNPs composites exhibited better mechanical performance, enhanced thermo-physical properties, and superior thermal conductivity, all of which could be attributed to the stronger interfacial interaction resulting from chemical bonding between the S@GNPs and the molecular chains of the rubber, relative to XSBR/GNP composites connected by weaker pi-pi stacking.