Surface treatments of hexagonal boron nitride for thermal conductive epoxy composites

Thermal issues increase with the electronic industry pushing towards fast in high speed, high density, and high performance. Thermal conductive materials are strongly demanded for increasing heat dissipation and reducing operating temperature of devices. Hexagonal boron nitride (h-BN) nanosheet that owns high thermal conductivity and low coefficient of thermal expansion is a good filler candidate to enhance the thermal conductivity of polymer composites. It is important to decrease the thermal contact resistance at the filler-matrix interface to increase the thermal conductivity of composite materials. However, there are few functional groups such as hydroxyl (-OH) on the edge planes of the h-BN particles. Acetone, nitric acid, silane coupling agent and some other surface treating agents have been used to improve the interface affinity between the fillers and matrix resin. In this paper, the h-BN particles prepared by liquid exfoliation of bulk h-BN flakes were first treated in sodium hydroxide solution or sulphuric acid solution to attach more functional groups onto the surfaces and then modified with 3-glycidoxypropyltrimethoxysilane (KH560). The treated particles were mixed with epoxy, and the mixture were then scraped into a glass mold and cured at proper temperatures. The thermal, mechanical properties were characterized by TGA, DMA, TMC, etc. The effects of the surface treating reagent on the thermal conductivity were discussed.