Integrated optimization of thermal and mechanical properties of electrical insulation paper based on APTES modification

Crepe insulation paper serves as the core insulation material for dry-type high-voltage bushings rated 110 kV and above, where integrated optimization of thermal and mechanical properties is critical for high-end product development. The intrinsic performance of flat-sheet insulation paper, as the basis of crepe insulation paper, directly determines the overall properties of the final product. Here, we employ a multiscale approach combining molecular simulations and experimental validation to systematically investigate the effects of APTES modification on the thermal, mechanical, and electrical properties of flat-sheet insulation paper. Molecular dynamics simulations reveal that a grafting ratio corresponding to 7% APTES treatment concentration achieves optimal modification, with thermal conductivity of 0.351 W/(m K), glass transition temperature of 455 K, Young’s modulus of 3.91 GPa, dielectric constant of 3.95, and hydrogen bonds increasing to 351 per unit cell. Experimental studies on modified base papers with 0%, 3%, 5%, 7%, and 10% doping confirm that the 7% sample exhibits superior overall performance, including glass transition temperature of 418.98 K, thermal decomposition temperature of 585.95 K, tensile strength of 6.902 N/mm, elongation at break of 1.492%, Young’s modulus of 3.602 GPa, dielectric constant of 4.25, breakdown strength of 42.1 kV/mm, and contact angle reduced to 63.7°. Further fabrication of epoxy resin/7% APTES-modified base paper composites demonstrates enhanced interfacial compatibility, with glass transition temperature of 398 K and breakdown strength of 68.2 kV/mm. These results reveal a coherent mechanism involving hydrogen-bond network reconstruction and enhanced interfacial interactions, which contribute to improved wettability with epoxy resin and strengthened interface bonding, thereby leading to elevated macroscopic properties. For dry-type bushing applications, the ~ 27.7% enhancement in thermal conductivity is particularly advantageous as it facilitates more efficient heat dissipation from winding hot spots, thereby reducing thermal stress and potentially extending service life. This mechanism offers theoretical direction and experimental support for the targeted design and development of high-performance insulation papers.