An Investigation into the Influence of Parylene Surface Modification on the Characteristics of Cellulose Insulating Paper for Eco-Friendly Fire-Retardant Transformers

The development of a novel ester-based oil-paper insulation system represents a crucial advancement in constructing eco-friendly fire-retardant transformers. However, owing to the inherent weak hydrolytic stability of ester-based insulating oil compared to traditional mineral insulating oil, a mutual promotion of hydrolysis occurs between ester-based oil and insulating paper, thereby accelerating the aging process of the oil-paper insulation system. To enhance the stability of the ester-based oil-paper insulation system, this study employed the chemical vapor deposition method, utilizing Parylene materials to create a novel surface-modified insulating paper. The paper systematically evaluated the hydrophobicity, AC breakdown performance, and thermal stability of the modified insulating paper. Results indicated excellent hydrophobicity, with water droplets forming a static contact angle of
$72.1^{\circ}$
on the paper surface. Moreover, the AC breakdown performance remained unaffected by Parylene surface modification. Thermogravimetric analysis revealed that the inclusion of Parylene material significantly enhanced the thermal stability of the insulating paper. The activation energy for the new insulating paper was determined to be 84.08 kJ/mol, accompanied by a pre-exponential factor of
$2.16 \times 10^6$
, surpassing that of the raw insulating paper at 82.03 kJ/mol with a pre-exponential factor of
$1.88 \times 10^6$
. This innovative surface modification strategy using Parylene material offers promising advancements in the performance and stability of ester-based oil-paper insulation systems.