Toward high-performance nanofibrillated cellulose/aramid fibrid paper-based composites via polyethyleneimine-assisted decoration of silica nanoparticle onto aramid fibrid.

Flexible paper-based nanocomposites dielectrics are of crucial importance in electrical insulation and advanced electrical power systems. In this work, a novel nanofibrillated cellulose/aramid fibrid (NFC/AF) composite was fabricated by vacuum-assisted filtration process. In order to improve the dielectric property of the composites, carboxylated nano-SiO2 was chemically coated onto aramid fibrid via molecular self-assembly with the aid of phosphoric acid (PA) pretreatment and subsequent polyethyleneimine (PEI) functionalization. It was found that composites prepared by NFC and (PEI/SiO2)-modified AF (after crosslinking) ((PEI/SiO2)-AF) showed dense structure, which was mainly due to enhanced interfacial interaction between AF and NFC. Consequently, NFC/(PEI/SiO2)-AF paper-based composites showed better tensile toughness (∼6 % elongation at break) and mechanical strength (∼36.28 MPa), in comparison with NFC/AF. More importantly, the electrical insulation performance and thermal stability of the composites were significantly improved. Accordingly, this work provides a facile approach to fabricate high-performance dielectric composites especially for high-temperature electrical insulation applications.