Enhanced mechanical and dielectric properties of natural rubber using sustainable natural hybrid filler

A natural hybrid filler (silica carbon black, name as SiCB) containing biochar and silica, was prepared from pyrolytic rice husk, and incorporated into natural rubber matrix. SiCB product exhibited very unique natural hybrid interface structure, which endows SiCB multiple-functional roles. It can act as good reinforcing filler to enhance mechanical properties and provide strong interfacial polarizability and dipole polarizability. As a result, when the content of SiCB was enhanced to 20 phr (parts per hundred of rubber), the tensile strength of the natural rubber composites was largely increased up to 30.28 MPa, which was two time higher to that of pure NR (15MPa). The dielectric constant at 10(3) Hz of the composites filled with 60 phr SiCB reached 7.62, which was 2.4 times of that of pure NR, because of the simultaneously improved interfacial and dipole polarizability. Moreover, the dielectric loss of all these composites at 10(3) Hz remained lower than 0.05. This work provides a simple and nontoxic method to prepare a sustainable natural hybrid filler and explore its novel application. Comparing with the rice husk ash, it can enhance the mechanical and electrical properties of the rubber composites at the same time. This will greatly expand the application of such biomass-based composite materials and this renewable resource.