Functionalized carbon black (CB) using three different surface modification methods: wet oxidation, epoxy monomer impregnation, and air oxidation, in single-epoxy composites and dual-matrix epoxy/poly(methyl methacrylate) PMMA composites at 15 vol% of CB content was studied in this research. The characterization on the surface modification CB was done via Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller (BET), and thermal gravimetric analysis. The phenol or ether, carboxylic acid, and epoxide functional groups were found on CB after surface modifications, along with a change in structure and BET surface area. Thermal degradation of CB was different after surface modification. This study further investigated the effect of the addition of surface-modified CB into epoxy resin, where the state of dispersion and distribution was observed under scanning electron microscopy. After surface modification, the mechanical testing via flexural and fracture toughness was done, where improvement was observed. A minor decrease in the electrical bulk conductivity of the composites was measured, which was due to a reduction in the degree of agglomeration. Both the thermal stability and CTE of surface-modified CB-filled epoxy composites show a decrement. Graphic abstract: Chemical modification of CB using air oxidation, wet oxidation, and epoxy monomer impregnation methods.[Figure not available: see fulltext.]
