▎ 摘　　要

NOVELTY - Graphene-modified corn stover core composite electromagnetic shielding film comprises upper film, an intermediate film and an underlying film, where upper film and lower film are both graphite oxide and olefin film. The intermediate film is a polyvinyl alcohol-graphene/biomass activated carbon film layer. USE - Graphene-modified corn stover core. ADVANTAGE - The graphene-modified corn stover core has good three dimensional network structure, improves the material m reflection and absorption capability of the electromagnetic wave, and promotes the development of light electromagnetic shielding material. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preparing composite electromagnetic shielding film, which involves: (A) pretreating the corn stalk core to remove the corn stalk from the straw epidermis, corn stalk core, vacuum drying at 60 degrees C for 2 ghours; (B) crushing, and passing through a 100 mesh sieve to obtain a straw core powder; (C) mixing straw core powder and zinc chloride aqueous solution in a mass ratio of 1:1 to 1.5, and stirring at 75 degrees C for 1 hour; (D) filtering through suction filtration, washing water, drying at 40 degrees C to obtain activated straw core; (E) preparing hybrid material by dispersing activated straw core powder in 0.1 g/mL water at, stirring wih a speed of 150 revolutions per minute, stirring for 10 minutes, to obtain uniform dispersion of straw core powder suspension; (F) adding 10 mg/g aqueous solution of graphene oxide dropwise, stirring for 30 to 60 minutes to obtain jelly, and then ultrasonicating for 30 minutes to obtain mixture of graphene oxide and straw core powder, where mass ratio of the graphene oxide in the graphene oxide solution to the activated straw core powder is 0.5 to 0.8: 0.2 to 0.5; (G) freezing drying graphene oxide and straw core powder mixture at (-20) degrees C for 12 hours to form solid state; (H) placing frozen solid in a freeze dryer and freeze-dried in vacuum atmosphere at (-45) degrees C for 12 hours to obtain three-dimensional porous graphene oxide-straw core powder composite; (I) treating three-dimensional porous graphene oxide-stalk core powder composite at 600-800 degrees C for 1 to 1.5 hours, protecting in inert gas protection, reducing to Graphene/biomass activated carbon hybrid material; (J) preparing composite film by mixing layer of 10 mg/g graphene oxide solution, coating on the surface of the polyester film, and drying at 50 degrees C for 0.5 hours to form the upper layer graphene oxide film; (K) mixing graphene/biomass activated carbon hybrid material with polyvinyl alcohol in mass ratio of 5:1, and uniformly coating on the graphene oxide film to form 0.3-1 millimeter intermediate film; (L) vacuum drying at 50 degrees C for 2 hours, and then coating with a layer of 10 mg/g solid graphene oxide; (M) calcining at 50 degrees C for 0.5 hours, drying to form lower layer of graphene oxide film; and (N) removing polyester film to obtain graphite-modified corn straw core composite electromagnetic shielding film.