ENHANCED THERMAL AND MECHANICAL PROPERTIES OF POLYCARBONATE COMPOSITES REINFORCED WITH AL₂O₃, GRAPHITE, AND HEXAGONAL BORON NITRIDE

Abstract

In this work, thermal conductivity and mechanical properties of polycarbonate (PC) composites reinforced with aluminium oxide (Al₂O₃) graphite, and hexagonal boron nitride (BN), were investigated at different filler loadings. Composites were prepared via melt mixing using a co-rotating twin screw extruder, with polydimethylsiloxane and amino-functional silane employed to improve filler dispersion. Through-plane thermal conductivity of PC/Al₂O₃ (30%) and PC/Graphite (30%) composites reached 0.6 and 3.01 W/mK, respectively, compared to 0.27 W/mK for PC. PC/Al₂O₃ remained electrically insulating, whereas PC/Graphite was conductive. PC/BN composites, particularly at 10–15 wt%, achieved thermal conductivity up to 1.05 W/mK while maintaining electrical insulation, with minimal impact on composite density. Mechanical properties were also influenced by filler type and loading. PC showed tensile stress at yield of ~73 MPa and elongation of ~5%. While Al₂O₃ and graphite reduced elongation, PC/BN composites maintained tensile stress at yield of 60–70 MPa and moderate elongation (2–3.5%) with elastic modulus, without significantly increasing density. These results highlight that BN is an effective reinforcing filler, providing an optimal combination of thermal conductivity, electrical insulation, mechanical performance, and lightweight characteristics. PC/BN composites at 10–15 wt% are promising for thermal management applications in electronics, energy storage, and automotive components.