Comparison of ZIFs and MWCNTs Co-optimization on the Dielectric Properties and Thermal Conductivity of Epoxy-Based Composites

ZIF-8 and ZIF-67 from the zeolitic imidazolate frameworks (ZIFs) family were grown on multi-walled carbon nanotubes (MWCNTs) by an in-situ growth method to prepare ZIF-8/MWCNTs (ZCNTs) and ZIF-67/MWCNTs (CCNTs) nanocomposite fillers which acted in the epoxy resin matrix. The structures of ZCNTs and CCNTs nanocomposite fillers were analyzed by SEM, XRD and FT-IR to investigate the effects of the two fillers with different contents on the dielectric properties and thermal conductivity of the epoxy resin matrix. The analysis revealed a notable discrepancy in particle size between ZIF-67 and ZIF-8, with the former being approximately 19 times larger under identical experimental conditions. Importantly, both ZCNTs/EP and CCNTs/EP composites exhibited improved thermal conductivity and thermal stability while maintaining a low dielectric constant (below 9.84 at 102 Hz) and a minimal dielectric loss (below 0.027 at 102–107 Hz). The thermal conductivities of CCNTs/EP at the same filler content were all higher than those of ZCNTs/EP, reaching a maximum at 0.3 wt.