Viscosity and thermal conductivity of alumina microball/epoxy composites

Filling ceramic particles that exhibit high thermal conductivity into a polymer is an effective way to enhance the thermal conductivity of the polymer. Alumina (Al₂O₃) microballs were chosen as the fillers to confirm whether their super-spherical structure would enlarge the maximum filling content of the filler into the polymer matrix. The impacts of Al₂O₃ microballs on the thermal conductivity of the composites and the viscosity of pre-curing suspension were investigated. The viscosity increased slightly when a 20 vol. % of Al₂O₃ microballs were filled, and when the filling content reached 50 vol. %, the viscosity was still relatively lower than that of the epoxy with roughly spherical AlN granules. A high thermal conductivity of 2.70 W/(m·K) was achieved with an Al₂O₃ microball content of 60 vol. %.