Corona Resistance of Fluorine‐Containing PI Modified With Si–Ti Composite Oxide Complexed With Nano‐ SiO ₂

ABSTRACT This study presents the production of Si–Ti composite oxides included with nano‐SiO ₂ dispersions, employing 2,2′‐bis(trifluoromethyl)‐4,4′‐diaminophenyl ether, 4,4′‐diaminodiphenyl ether, and homophthalic tetracarboxylic acid dianhydride as reaction monomers. A series of fluoropolyamide acid precursors with varying doping levels were synthesized via in situ polymerization based on a molar ratio of n (ODA): n (6FODA) = 1:9. Subsequently, Si–Ti/SiO ₂ /FPI composite thin films were fabricated through calendering techniques. This study emphasizes the influence of different doping levels on the dielectric properties and corona resistance of FPI composite films. The results demonstrate that the integration of Si–Ti composite oxides with nano‐SiO ₂ markedly improves the corona resistance longevity of the composite film. Additionally, its efficacy at elevated frequencies is greatly enhanced. These composites show relatively low dielectric constants and dielectric losses. At a doping level of 16 wt%, the corona duration reaches an astounding 3.16 h at 10 ⁵ Hz, 155°C, and an electric field intensity of 80 kV/mm.