Performance Investigation of Nanomodified Cellulose Insulation Paper Under Electric Field Conditions

Cellulose insulation paper used in oil-immersed power transformers is vulnerable to molecular chain loosening and aging-product transport under thermal and electrical stresses. Nanomodification is a promising route for improving insulation-paper stability, but the atomistic mechanisms by which KH550-grafted oxide nanoparticles regulate cellulose structure and aging-molecule mobility under an external electric field remain insufficiently clarified, particularly when the role of oilpaper insulation aging and oil-contact environments is considered. In this work, pristine cellulose and cellulose modified with KH550-grafted SiO2 and Al2O3 nanoparticles were investigated using molecular dynamic simulations at 343 K under a uniform electric field of 0.01 V/Å (100 kV/mm) applied along the Z-axis. Based on the MSD and apparent transport-parameter results, nanomodification reduced the MSD-derived apparent coefficients of H2O and CO2 by 33.7–51.9%. The external field produced apparent directional transport bias, with Z/X apparent-coefficient ratios of 2.21 for H2O and 2.02 for CO2 in pristine cellulose. These ratios decreased to 1.62 and 1.51, respectively, in the KH550–Al2O3 model. Interfacial interaction energy analysis showed that the KH550–SiO2 interface became more strongly bound under the field (−240.50 to −252.13 kcal/mol), whereas the KH550–Al2O3 interface remained nearly unchanged (−541.65 to −538.81 kcal/mol). Because the two nanomodified systems use different nanoparticle loadings and KH550 grafting ratios, cross-system differences are interpreted as model-specific outcomes rather than effects attributable only to nanoparticle chemistry. These results indicate that KH550-grafted nanoparticles may help maintain cellulose packing under the modeled conditions and suppress aging-molecule mobility in the simulated cellulose matrix, while the conclusions should be interpreted as atomistic simulation evidence rather than direct proof of long-term transformer reliability.