Enhancement of comprehensive performances on electrical and waterproof properties for cellulose insulating paper with plasma treatment

Plasma polymerization is induced above and within the cellulose insulating paper. • Electrical, waterproof, and mechanical performances are enhanced simultaneously. • Surface and bulk insulation strength is improved for oil-paper insulation system. • Silicone crosslinking networks are constructed between cellulose porous structures. The oil-paper insulation system is widely used in power transmission devices such as the transformer and bushing, and the cellulose paper, immersed in oil serving as the primary insulation dielectric material, plays the pivotal role in ensuring reliable operation of the devices. However, it remains a challenge for the cellulose paper to possess long-term sufficient insulation performance in high-voltage, oil-immersed and water-contained complex environments due to its high dielectric constant and hydrophilicity compared with the oil, prone to absorb charge and moisture from the oil-paper interface to the bulk, making it vulnerable to breakdown failure. Herein, we propose to initiate polymerization on the surface and within the bulk of the cellulose insulating paper enabled by atmospheric low-temperature plasma treatment, constructing low-polarity crosslinking network between its intrinsic porous structures, thereby comprehensively enhancing versatile properties, specifically oil-paper dielectric constant adaptation, mechanical and insulation strength improvement, and moisture absorption suppression. The relative dielectric constant of the insulating paper is decreased by 44.4%, enabling its adaptation with the insulating oil. The wetting performance is changed from hydrophilic to superhydrophobic, reducing water absorption by 37.2%, inhibiting the transportation of water from the surface to the bulk. The insulation strength of the oil-paper system is enhanced by more than 22.9% by introducing deep traps, which inhibit the charge transportation and partial electric field distortion. The plasma-enhanced insulating paper and its improvements of comprehensive performances provide potential application for safe and stable power transmission. Download: Download high-res image (423KB) Download: Download full-size image