▎ 摘　　要

NOVELTY - A high-dielectric polyimide composite film comprises 0.01-0.02 pts. wt. vanadium pentoxide, 2-3 pts. wt. expanded graphite powder, 10-12 pts. wt. pyromellitic dianhydride, 8-10 pts. wt. 4,4-diaminodiphenyl ether, 0.01-0.02 pts. wt. graphene, 3-5 pts. wt. N-vinyl-pyrrolidone, 20-25 pts. wt. N,N-dimethylacetamide, 3-5 pts. wt. ethanol, 0.1-0.2 pts. wt. silane coupling agent, 0.4-0.5 pts. wt. hydroxyethyl methacrylate, 0.1-0.2 pts. wt. polyvinyl alcohol, 4-5 pts. wt. water, and appropriate amount of 10% boric acid solution. USE - High-dielectric polyimide composite film for load capacitor. ADVANTAGE - The polyimide composite film has excellent dielectric property, mechanical property and processing property, and low dielectric loss. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for the preparation of high-dielectric polyimide composite film, which involves immersing expanded graphite in boric acid solution for 6-8 hours, washing expanded graphite with water, drying expanded graphite, dissolving polyvinyl alcohol and vanadium pentoxide in water to form a solution, adding dried acid-treated graphite and graphene to the solution, ultrasonically dispersing for 20-30 minutes, mixing slurry, heating at 60-80 degrees C, grinding for 30-40 minutes, drying resulting slurry, completely removing water, evenly mixing resulting powder with silane coupling agent to obtain surface-modified expanded graphite-graphene composite powder, mixing the composite powder with anhydrous ethanol, ultrasonically dispersing for 20-30 minutes, adding 4,4-diaminodiphenyl ether to N,N-dimethylacetamide and stirring, adding pyromellitic dianhydride, reacting for 10-12 hours to form polyamic acid adhesive, adding surface-modified expanded graphite-graphene composite powder and polyamic acid adhesive to absolute ethanol, stirring for 8-10 hours, adding other materials, continuously stirring the mixed material to obtain a composite adhesive, applying composite adhesive on a glass plate, and carrying out imidization process in a air-forced oven at a temperature of 150-200 degrees C for 1-2 hours.