Experimental validation and numerical modeling of interfacial effects in silanized hexagonal boron nitride (h-BN) reinforced epoxy composites by tailoring silane concentration

This study investigates the use of h-BN particles as fillers, focusing on tailoring surface chemistry to enhance the thermal conductivity of epoxy composites. By enriching the interface between h-BN particles with amino-silane groups and the epoxy matrix through controlled surface modification, thermal performance, and interfacial bonding were improved. To achieve a high degree of functionalization, h-BN particles were oxygenated to 13.6 atomic percent (at. %) through thermal treatment, followed by reduction using 3-amino-propyl-3-ethoxy-silane (APTES), which increased the amino content by 3.5% at. % under optimized reaction conditions. During composite manufacturing, 10 wt.% functionalized h-BN particles were reinforced into the epoxy matrix, increasing bulk thermal conductivity by 53%, from 0.2 W/mK to 0.34 W/mK. Heat flux simulations with ANSYS confirmed the interface interactions and thermal performance, with silanized h-BN achieving the highest heat flux of 70 W/mm2, aligning well with experimental results. While silanization improved thermal conductivity by strengthening interfacial bonding between h-BN and the epoxy matrix, it introduced brittleness, making the composites stiffer and more fragile. However, the silanized h-BN composite showed a 57.14% increase in toughness compared to neat h-BN, while the highest flexural modulus of 4126 MPa was achieved with neat h-BN.