Study on thermal conductive epoxy adhesive based on adopting hexagonal boron nitride/graphite hybrids

The effect of hybrid filler on newly developed thermal conductive epoxy adhesive has been reported in this paper. The hybrid filler containing hexagonal boron nitride (h-BN) and graphite (Gr) with the mass ratio of 1:1 was loaded in to the epoxy resin with different wt% ratio (10:90, 20:80, 30:70, 40:60, 50:50 and 60:40). The corresponding thermal conductivity of adhesives was measured using guarded heat flow meter technique which enhanced up to 2.025 W/mK with the loading of 60 wt% of hybrid filler. Lap shear strength of the adhesive containing 40 wt% of hybrid filler was higher than the pristine epoxy resin thereby confirming reinforcing effect of hybrid filler into the epoxy matrix. Afterward, the shear viscosity of uncured epoxy resin filled with hybrid fillers were analyzed by using parallel plate rheometry. Strong shear thinning behavior was exhibited at higher hybrid filler loading. Further, lower loss factor and higher T_g values were observed with increase in the hybrid filler (h-BN/Gr) loading thereby confirming the higher cross linking density and lower mobility of epoxy chain. Thermal stability of hybrid Gr/BN–epoxy composite adhesives was studied using thermo gravimetric analyzer. Scanning electron microscopy confirmed the uniform deposition of hybrid filler on to the surface of epoxy resin.