Preparation of Meta-Aramid Composite Paper with High Breakdown and Tear Strength via an Interface-Engineered Strategy

Abstract

The intrinsically high porosity and pronounced surface roughness of meta-aramid paper severely compromise its dielectric breakdown strength, thereby restricting its application in extreme environments. Conventional strategies aimed at enhancing breakdown strength typically lead to a concomitant deterioration in tear strength, creating a critical trade-off. Herein, we report robust bilayer-structured composite papers fabricated by integrating a high-concentration poly(m-phenylene isophthalamide) (PMIA) wet film with meta-aramid paper. Through a tailored pressing process, the PMIA not only infiltrates the internal pores of meta-aramid paper but also forms a dense surface layer that substantially reduces structural defects. Benefiting from the formation of multi-scale interfaces and hydrogen-bond networks, the bilayer composite papers exhibit improved tensile strength and tear strength over a broad temperature range. Furthermore, the optimized bilayer composite paper achieves a breakdown strength of 58.4 MV/m at room temperature (RT) and 51.4 MV/m at 120 °C, representing enhancements of 102% and 89.9%, respectively, compared with that of conventional meta-aramid paper. Finite element simulations further reveal that the PMIA layer acts as an effective barrier against electrical tree propagation, thereby delaying dielectric failure. This simple and scalable strategy effectively attenuates the deterioration of tear strength generally associated with enhancing breakdown strength, thus mitigating the severe trade‑off typically observed in other modification routes with reduced loss of tear strength while improving breakdown strength, offering a promising avenue for the development of next-generation advanced insulating materials.