Construction and properties of epoxy resin-based conductive and thermally conductive composites with electromagnetic shielding function

The construction of 3D networks enhanced filler utilization in conductive composites, but heat-induced liquefaction of solid epoxy resins hindered internal 3D structure formation. This study prepared semi-cured epoxy particles (S-E12-RGs) by mixing and pre-curing E12 epoxy with a curing agent. S-E12-RGs were combined with liquid epoxy E51, curing additives, and ethylenediamine-modified nickel-coated graphite (ENCG), and then hot-pressed into 3D composites. The crosslinking of S-E12-RGs prevented ENCG's inward migration, which promoted its selective dispersion in the E51 phase. With only 15 wt% nickel-coated graphite (NCG), the conductivity increased by 7 orders of magnitude compared to direct filling. At 25 wt% ENCG, the composites achieved a conductivity of 23.81 S/m, a thermal conductivity of 0.557 W/(m K), and an EMI shielding of 35 dB. Furthermore, DMA-digital multimeter analysis showed that ΔR/R 0 was less than 0.27 from 35 to 70°C at 0.1–50 Hz, which demonstrated excellent operational stability. Highlights A 3D network was formed in the thermosetting matrix via specific methods. The cross-linked S-E12-RGs promoted ENCG's selective dispersion in the E51 phase. The composite exhibited high electrical conductivity at low filler content. The material maintained stability within a specific temperature and frequency range.