Aminosilane-driven crosslinked network construction for improved thermal stability of cellulose-based insulation pressboard

The service life of oil-immersed transformers is closely linked to the durability of insulation pressboard, which is often compromised by thermal aging during prolonged high-temperature operation. To enhance the thermal stability of cellulose insulation pressboard, this study proposes a modification technique based on aminosilane treatment. The modified pressboard is characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and mercury intrusion porosimetry (MIP). The combined results confirm that aminosilane grafts amino groups onto the cellulose fibers and forms a cross-linked network among them. Compared to the unmodified insulation pressboard, the aminosilane-modified insulation pressboard exhibits a 7.42 % decrease in dielectric constant and a 7.42 % increase in elongation at break. The contact angle increases from 75.7° to 99.4°, indicating enhanced hydrophobicity. Aminosilane modification enhances the thermal stability of the insulation pressboard. Throughout the aging process, the modified pressboard consistently demonstrates superior performance in key metrics such as degree of polymerization (DP), dielectric properties, and mechanical strength. After 30 days of thermal exposure, the modified pressboard exhibits a 44.14 % increase in DP, a 7.76 % decrease in dielectric constant, and a 2.3 % improvement in elongation at break relative to the reference sample.