Thermally Conductive Polypropylene Nanocomposites Based on Mechanically Exfoliated Boron Nitride Nanosheets

Thermally conductive (TC) nanocomposites have been used increasingly in miniaturized electronic devices to hinder heat accumulation. By leveraging the lightweight nature of polymeric matrices and incorporating TC fillers, such as hexagonal boron nitride (hBN), high-thermally conductive materials with higher tensile strength can be developed. In this study, mechanically exfoliated hBN (20 wt%) was compounded with polypropylene (PP) to fabricate TC nanocomposites. Parameters such as sonication power, sonication time, and particle size of the hBN were optimized, and the mechanical and thermal properties of the nanocomposites, along with alkyl modification, in comparison to raw and exfoliated boron nitride nanosheets (BNNS), were examined. BNNS-based PP demonstrated improved tensile strength and elastic modulus, accompanied by a decrease in ductility. A high elastic modulus (3386 MPa-ABN/PP20.40-2) was obtained from the alkyl-modified samples. The sample containing 20 wt% BNNS (BNNS/PP20.40-3), which was subjected to 1500 W of sonication for 8 h, demonstrated an improved thermal conductivity of 0.54 W/mK, compared to ABN/PP20.40-2 (0.4 W/mK). This reflects a 125% and 80% enhancement compared to pure PP (0.24 W/mK) and smaller-sized hBN-based samples coded BNNS/PP20.750 (0.304 W/mK), respectively.