Study on the thermal and dielectric properties of covalently modified GO/XNBR composites

Abstract

The development of multifunctional and miniaturized electronic devices requires the related materials to possess higher dielectric constant (DC), lower dielectric loss, and higher thermal conductivity. In this study, first, five functional groups are selected to modify graphene and determine the most favourable functional group to increase the DC of graphene/carboxylated acrylonitrile butadiene rubber systems by molecular dynamics (MD) simulation. Second, polymer polyethyleneimine (PEI) with different structure and molecular weight is used to reduce graphene oxide simultaneously in experiments. The results show that branched PEI helps to enhance DC values. In addition, the linear low molecular weight PEI assists in the mechanical and thermal performances, whereas linear high molecular weight PEI synchronously improves the dielectric, mechanical, and thermal performances. Subsequently, the combination of experiments and MD simulations provides in-depth insight into the mechanism and influencing factors for the ameliorative properties. The simulation results indicate that the meliorated dielectric, thermal, and mechanical properties of composites are mainly related to the interface behaviour, including interface compatibility, interface bonding strength, interface phonon vibration power spectrum, and interface hydrogen bonds. This research provides a theoretical basis to prepare high-performance composites required in the application of electronic devices.

Keywords

• Rubber composites
• Molecular simulation
• Dielectric constant
• Thermal conductivity
• Graphene oxide