Enhanced Thermal and Mechanical Performance in Insulated Aramid/Functionalized Graphene Composite

Poly-(meta-phenylene isophthalamide) (PMIA) is a high-performance polymer with excellent insulation and thermal stability, making it an ideal material for use in next-generation electric and electronic devices. However, its low thermal conductivity limits its further applications. In this work, functional graphene with high thermal conductivity and potential insulation properties is introduced into the PMIA matrix. The comprehensive performance of the composite is explored through molecular simulations. Four functional graphene models with hydroxy (–OH), carboxyl (–COOH), amino (–NH2), and fluorine (–F) groups are constructed, and their thermodynamic properties, mechanical properties, and electronic band structures are calculated. The results show that the thermal conductivity and glass transition temperature of the PMIA/graphene–COOH composite are increased by 87.4% and 66.42 K, respectively. In addition, Young’s modulus and shear modulus are increased by 48.8% and 43.1%, respectively. The improved performance is attributed to the strong intermolecular interactions between the functional groups on graphene and the PMIA matrix. Furthermore, graphene oxide (–OH and – COOH) and fluorinated graphene (–F) as two representative types of functional graphene are added into the PMIA matrix. The dielectric strength is reasonably increased rather than deteriorated, which matches well with the electronic band structure simulations, where trap states are deepened by functional groups.

I. Introduction

Poly-(meta-phenylene isophthalamide) (PMIA) has garnered significant attention in the past decade due to its superior dielectric strength, mechanical properties, and thermal stability [1], [2]. Aramid papers and films, which are fabricated from PMIA fibers [3], inherit all of the aforementioned advantages and have found widespread applications as insulation protection materials in electrical and electronic equipment, such as transformer winding insulation [4] and motor coil insulation [5]. However, the intrinsic thermal conductivity of PMIA fibers, which is below 0.2 W/(), limits its ability to effectively dissipate heat during the operation of high-power electrical equipment [6], [7]. The localized heat accumulation can accelerate insulation aging and potentially lead to thermal breakdown faults [8]. Hence, further modification is required to enhance the thermal conductivity of the aramid-based composite.