H-BN/Cellulose insulation paper with high thermal conductivity, excellent mechanical strength, and electrical properties: Experimental and molecular dynamics study

Abstract

With the rapid advancement of the power industry, transformers, as crucial components of power systems, require further improved insulation properties for their internal dielectric materials. This study aims to improve the thermal conductivity, mechanical strength, and electrical properties of cellulose insulation paper (Cellulose-IP). To achieve this, composite Cellulose-IP with different doping ratios of hexagonal boron nitride (h-BN), ranging from 1 to 5 wt. %, was prepared and tested. The results demonstrated that the composite with 2 wt. % h-BN exhibited the best overall properties. Specifically, this composition resulted in increases in tensile strength and elongation at break of 24.3% and 25.8%, respectively. Additionally, improvements in thermal conductivity and electrical properties were observed. Molecular dynamics simulations further revealed that 2 wt. % h-BN effectively filled the gaps between cellulose molecular chains, thereby reducing the free volume fraction of the composite, limiting chain displacement, and decreasing phonon scattering. The presence of h-BN also facilitated the formation of additional intermolecular hydrogen bonds, which enhanced the mechanical strength of the Cellulose-IP. Furthermore, the electrostatic potential of h-BN and the interfacial interactions between h-BN and cellulose contributed to reduced electron migration and minimized polarization loss, and these factors collectively improved the electrical properties of the Cellulose-IP.