Influence of curing agent modified BN with different molecular structures on the heat conduction and electrical insulation property of epoxy composites

Abstract Boron nitride (hBN) serves as an outstanding high‐performance polymer organic filler. However, its hexagonal crystal structure renders it chemically inert, thus limiting its applications. This study proposes the modification of hBN using economical amine and anhydride curing agents to reduce aggregation and enhance the heat conduction of epoxy resin. Specifically, the DETA curing agent and methyl tetrahydrophthalic anhydride (MTHPA) curing agent were grafted onto the hBN surface via ball milling and eco‐friendly water scrubbing processes. Subsequently, the modified functionalized BNNS were uniformly dispersed in epoxy resin via a wet process to form composite materials. Results indicate that both modified fillers maintain good dispersion at the epoxy interface. Compared to epoxy resin, the heat conduction of the EP/MTHPA‐BNNS composite material with 10 vol% loading increased by 212%. The EP/DETA‐BNNS composite exhibited a relative thermal conductivity enhancement of 191%. Moreover, both of materials demonstrated significantly improved thermal stability, with slightly reduced breakdown strength. Mechanical property testing revealed a maximum increase of 187.5% in fracture elongation. Highlights Comprehensive study on curing agent modified hBN High dispersion of BNNS after wet ball milling Modified BNNS improves composite interface properties The thermal conductivity increases twice under 10 wt% BNNS loading Composite materials with outstanding electrical insulation and high fracture elongation