▎ 摘　　要

NOVELTY - Preparing graphene/polyvinylidene fluoride composite material involves using 200 mesh and 300 mesh sample sieves to screen the graphite powder, and finally passing particle size through the 200 mesh sample sieve, where graphite powder which do not pass the 300 mesh sample sieve is used as the raw material. The 3g screened graphite powder is taken and added to the round bottom flask, 12ml concentrated sulfuric acid, 2.5g potassium persulfate and 2.5g phosphorus pentoxide are added to the round bottom flask, and heated in a water bath of 80 degrees C, stirred for 5 hours, then cooled to room temperature, 500 ml deionized water is added to the product for dilution, and then stand overnight. The mixture is filtered with a nylon microporous membrane having a pore size of 0.4 micrometer, and then washed product to neutral with a large amount of deionized water, and dried to obtain pre-oxidized graphite. The pre-oxidized graphite obtained is added to 120 ml of concentrated sulfuric acid into beaker. USE - Method for preparing graphene/polyvinylidene fluoride composite material. ADVANTAGE - The method enables to prepare graphene/polyvinylidene fluoride composite material which has reduced percolation threshold of the composite. DETAILED DESCRIPTION - The 15 g potassium permanganate is adedd to the beaker. The beaker is placed in an ice water bath during process. The glass rod is stirred throughout the reaction system so that the temperature of the entire reaction system is controlled below 20 degrees C, and then the reaction is continued at 35 degrees C for 2 hours, then 250 ml of water is slowly added to the reaction system followed by a concentration of 20 ml. A 30% aqueous solution of hydrogen peroxide is added to the reaction system, and the suspension changes instantaneously to golden yellow. The product is washed with 1:10 of dilute hydrochloric acid of 1 :10, and then washed with 0.5 L of deionized water, and then the remaining substance is removed, put into a dialysis bag, placed dialysis bag in deionized water for dialysis until the suspension is neutral, and finally introduce product into a culture dish and dried at 80 degrees C to obtain a dark brown graphite sheet. The polyaniline (EB) to dimethylformamide are added, stirred at 70 degrees C for 2 hours, cooled to room temperature, filtered through a 0.4 micrometer filter to obtain dark blue filtrate. An appropriate amount of graphite oxide sheet is added to dimethylformamide and ultrasonically dispersing for about 2 hours, and then the filtrate is added to the suspension of the graphite oxide sheet to continue ultrasonic dispersion for about 1 hour. The suspension is placed in a water bath at 90 degrees C, and an appropriate amount of hydrazine hydrate (in which the ratio of hydrazine hydrate to the graphite oxide sheet is about 20microliter: 1 mg) is added under magnetic stirring, and the reaction is continued. The system is cooled to room temperature. The suspension is filtered through a nylon microporous membrane of 0.4 micrometer, and washed with DMF until the filtrate is clarified, and finally the obtained wet product is dispersed in the DMF solution to obtain a REB suspension. An appropriate amount of the REB suspension is added to the DMF, and after ultrasonic dispersion, the suspension is placed in a water bath and heated to 70 degrees C, and an appropriate amount of polyvinylidene difluoride powder is added under mechanical stirring to continue the reaction for 2 hours. The obtained liquid is poured into a large amount of ethanol, and after standing for 3 hours to obtain bulk composite material. An INDEPENDENT CLAIM is included for a method for testing graphene/polyvinylidene fluoride composite material, which involves: (A) hot pressing bulk composite material at 190 degrees C, 20 mega psacals for 10 minutes on a hot press, and cooling to obtain a sheet composite material having a diameter of about 1 cm and a thickness of about 1 mm; (B) placing prepared powdery or bulk composite sample directly on a glass slide after solvent removal, and testing spectrum by a spectrometer with a laser wavelength of 631 nanometer; (C) drying all samples before testing, and subjecting samples to contact angle test using a video contact angle measuring instrument; (D) placing prepared composite material in liquid nitrogen for quenching, and observing cross-sectional morphology of the composite material by a scanning electron microscope; (E) dispersing prepared powder sample ultrasonically in a DMF solvent, and then dropping onto the silicon wafer, and fixing silicon wafer on the homogenizer and then rapidly rotating to uniformly disperse the sample, and drying silicon wafer at room temperature, observing under AFM to complete the AFM test of the composite material; and (F) applying electrode on the front and back surfaces of the composite sample of about 1 mm thick, using multimeter to check whether the electrode is turned on, and then placing sample between the electrodes of the instrument, and then using range of 20-150 degrees C to test graphene/polyvinylidene fluoride composite material.