High-strength, electrically insulated industrial meta-aramid paper reinforced with polyethylene terephthalate microfibre pulp in a sandwich structure

The weak interfacial strength and porous structure of the meso-aramid paper cause mechanical and insulating deficiencies. Enhancing density, regulating pore structure, and improving interfacial interactions of meso-aramid are crucial for promoting the performance of meso-aramid papers. A PMIA/polyethylene terephthalate (PET) composite paper was prepared using the wet method with meso-aramid short cut fibres (PMIA) and PET pulp as raw materials. The sandwich-structured PMIA/PET paper was achieved by covering PET microfiber non-wovens served as the surface layer while the PMIA/PET composite paper acted as the core layer. During the high-temperature hot pressing process, the PET pulp transformed into a viscous melt that coated on aramid fibres in between layers, forming a typical ‘reinforced concrete’ interface structure within the core layer of the PMIA/PET composite paper. The PET non-wovens on top and bottom surfaces were converted into a dense PET film that filled and covered the holes and defects in the PMIA/PET composite paper. This unique structure enabled the sandwich-structured PMIA/PET composite paper to exhibit excellent tensile strength (80.41 N/cm) and breakdown strength (56.35 kV/mm), surpassing most reported performances of meso-aramid papers in literature. This work not only provides novel insights for preparing high-performance meso-aramid papers, but also shows potential applications for other materials and structures.