Nano-kaolin enhances the mechanical, electrical, and thermal properties of cellulose insulating paper

There is an extremely urgent demand in the realm of power equipment, including power transformers, motors, and cables. Specifically, there is a pressing need for cellulose-based composite insulating paper that can exhibit high thermal conductivity, superior mechanical properties, and robust insulation characteristics. In response to this demand, this study adopted a ‘simulation-guided experimental research’ methodology. First, based on molecular dynamics (MD) simulations, it was used to construct nano-kaolin (KL)/cellulose composite models with varying contents. Then, according to the simulation results, the corresponding proportions of nano-KL/cellulose insulating paper were prepared. The simulation and experimental findings further reveal a significant effect of nano-KL. To be more precise, nano-KL can effectively fill the microscopic defects and voids within the cellulose structure. Moreover, nano-KL forms an orderly and regular thermal conductivity network in conjunction with cellulose. As a result, this network structure elevates the paper's overall thermal conductivity. Owing to its low-dielectric-loss characteristics, nano-KL reduces the microscopic charge polarisation phenomenon within the composite structure. It curbs the migration of electrons, alleviates the concentration of electric field stress, and ultimately improves the electrical insulation performance of the modified insulating paper. Notably, the 4 wt% nano-KL/cellulose insulating paper exhibits optimal performance, and its tensile strength, thermal conductivity, volume resistivity, dielectric loss, and breakdown strength are 55.81 MPa, 0.201 W·m⁻¹ K⁻¹, 4.58 × 10¹⁵ Ω·m, 0.25%, and 57.81 kV/mm. This study demonstrates MD simulations' feasibility and effectiveness in providing theories and protocols for experiments.