SiO₂@Al₂O₃ binary filler: A chance for enhancing the heat transport in rubber composites for tire applications

Abstract The present study reports on the development of a new binary filler system for rubber composites, SiO₂@Al₂O₃, where Al₂O₃ sheets are grown onto SiO₂ nanoparticles aggregates by a sustainable water‐based soft‐chemistry approach. The aim is to synergistically integrate the intrinsic thermal conductivity properties of Al₂O₃ with the peculiar reinforcement ability of SiO₂ in an easy one‐pot solution, which has been exploited to prepare polybutadiene (PB) model composites by a simple solvent casting technique. More in detail, the binary filler was used as‐prepared or suitably surface functionalized with 3‐(Trimethoxysilyl)propylmethacrylate (TMSPM). The filler compatibilization and interplay with the polymeric matrix have been inspected by solid state NMR in conjunction with scanning electron microscopy. These investigations highlighted that the presence of alumina in the binary filler does not undermine the capability of silica in generating polymer chains stiffening and indicated a significant effect of the silanization in providing better filler networking and interaction with the PB host ensuring, in principle, an enhanced thermal transport. Accordingly, thermal conductivity measurements revealed that SiO₂@Al₂O₃ introduction in PB induces a remarkable upgrade of the heat transfer, which becomes much more relevant upon surface modification with TMSPM. These results appear encouraging, paving the possibility of applying SiO₂@Al₂O₃ model system to more complex case studies, where both improved thermal conductivity and enhanced reinforcement are required, such as tires tread formulations. Highlights A new SiO₂@Al₂O₃ binary filler system was proposed following a soft‐chemistry approach. The binary filler was functionalized to enhance its compatibilization. Fillers were dispersed in polybutadiene by a simple solvent casting technique. Thermal conductivity measurements revealed a remarkable upgrade of the heat transfer ability.