▎ 摘　　要

NOVELTY - Preparing composite graphene electrothermal film involves preparing graphene oxide solution by a modified Hummers method, and washing to neutrality, weighing 0.5 grams sodium nitrate powder and 70 mL concentrated sulfuric acid, putting into 500 mL beaker, transferring the beaker into the ice water mixture, and stirring in ice water bath at 0 degrees C for 30 minutes to dissolve sodium nitrate completely. 1 grams spherical graphite is weighed, slowly added to the beaker, continue to stirred for 30 minutes, graphite is uniformly mixed. 3 grams potassium permanganate is weighed, slowly added to the beaker at a rate of 1 gram every 10 minutes, whole process lasts for 30 minutes. The whole process medium control temperature does not exceed 10 degrees C. The potassium permanganate is added, stirred at high speed for 2 hours, then the solution gradually turns into dark green. The beaker is moved into a 35 degrees C water bath and continue to stir for 2 hours and added to 100 mL beaker deionized water at 80 degrees C. USE - Method for preparing composite graphene electrothermal film. ADVANTAGE - The method enables to prepare composite graphene electrothermal film in simple and cost effective manner which consumes less energy in which product has excellent thermal conductivity and electrical conductivity. DETAILED DESCRIPTION - Preparing composite graphene electrothermal film involves preparing graphene oxide solution by a modified Hummers method, and washing to neutrality, weighing 0.5 grams sodium nitrate powder and 70 mL concentrated sulfuric acid, putting into 500 mL beaker, transferring the beaker into the ice water mixture, and stirring in ice water bath at 0 degrees C for 30 minutes to dissolve sodium nitrate completely. 1 grams spherical graphite is weighed, slowly added to the beaker, continue to stirred for 30 minutes, graphite is uniformly mixed. 3 grams potassium permanganate is weighed, slowly added to the beaker at a rate of 1 gram every 10 minutes, whole process lasts for 30 minutes. The whole process medium control temperature does not exceed 10 degrees C. The potassium permanganate is added, stirred at high speed for 2 hours, then the solution gradually turns into dark green. The beaker is moved into a 35 degrees C water bath and continue to stir for 2 hours and added to 100 mL beaker deionized water at 80 degrees C, the beaker is transferred into a water bath of 85 degrees C for 30 minutes, mixture is transferred to a 1 L beaker, diluted at 500 degrees C in 500 mL deionized water, and then 60 mL 5 wt.% aqueous solution of oxygen is added until the solution is bright yellow, no more bubbles are generated, and stirred for 20 minutes. The mixture is alternately washed with 10% hydrochloric acid solution and deionized water, and repeated for 4 to 5 times until solution is neutral. The solution is pre-frozen, frozen-dried, the neutral graphene oxide solution is diluted and put into the material tray, the vacuum refrigerator is opened, and the vacuum refrigeration is first performed. The refrigerating chamber of the machine is pre-frozen, material tray is placed in the pre-freezing rack of the refrigerating warehouse, the cooling probe is fully contacted with the material, and then the freezing rack is placed in the cold trap, and the pre-freezing cover is covered, when pre-freezing to the material, each unit falls below the eutectic point of the material, and maintained for 1-1.5 hours, and the pre-freezing is finished. The pre-frozen material is moved to the gland dryer, and then the dryer is placed in the cold trap on the cover, cover the plexiglass cover, screw the drain valve, open the vacuum gauge, and vacuum the cold trap with a vacuum pump to make the internal vacuum less than 20 Pascals, and the drying time is 2-5 hours, to obtain the fluffy graphene oxide solid. The oxidation preparation of the olefin dispersion is performed by weighing the dried graphene oxide solid, adding to water, preparing a graphene oxide solution having mass fraction of 1 wt.% and then performing a shear emulsification operation on the mixture to enable the clustered structure to disperse under the action of high-speed shearing to obtain more uniform dispersion, shear emulsification rate of 1100-1200 revolutions/minute for 3-7 minutes. The dispersion is moved into the ultrasonic system for ultrasonic operation for 1 hours to obtain oxidized graphene dispersion. The concentration of the graphene oxide dispersion is adjusted to 10 mg/mL concentration or dilution and the graphene is immersed in 10 mg/mL glass substrate, coated in liquid, then immersed the glass substrate with the graphene oxide dispersion in 0.1 moles/mL coagulating liquid to form gel. The graphene oxide composite film is prepared by taking out the substrate, and placing the substrate drying in a dry box, controlling the drying temperature to 50-70 degrees C for 6-8 hours. The glass substrate is covered with a layer of graphene oxide composite film, film is peeled off from the glass substrate to the graphene oxide composite film, graphene oxide composite film is reduced to obtain composite graphene electrothermal film, and the above-mentioned graphene oxide composite film is reduced by steaming with hydroiodic acid at 80 degrees C for 24 hours. The graphene composite film is calendered by a calender to obtain a composite graphene electrothermal film.