▎ 摘　　要

NOVELTY - Graphene comprises 2 parts mass crystalline flake graphite, 8-16 parts mass potassium permanganate, 80-90 parts mass concentrated sulfuric acid, 10-20 parts mass phosphoric acid and 5-20 parts mass ascorbic acid. USE - As graphene (claimed). ADVANTAGE - The graphene has higher oxygen to carbon ratio, more oxygen-containing groups and higher degree of exfoliation, is mild and reduces toxins due to the usage of ascorbic acid and the method increases the amount of oxidant potassium permanganate or reduces the amount of ascorbic acid, increases the residual amount of the graphene group and reduces the degree of graphene residual level by controlling the amount of the oxidizing and reducing agent. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) method for preparing the graphene involves (a) uniformly mixing crystalline flake graphite, potassium permanganate, concentrated sulfuric acid and phosphoric acid in a weight ratio of 2:8-16:80-90:10-20 to obtain mixture and heating the mixture at 30-60 degrees C for 8-12 hours to obtain the graphene oxide, (b) cleaning the graphene oxide with deionized water to obtain cleaned graphene oxide, removing the residual oxidant and dispersing the cleaned graphite oxide in less than or equal to 5 mg/ml deionized water to obtain graphene oxide water system and (c) uniformly mixing the graphene oxide water system obtained in step (b) with ascorbic acid to obtain mixture, refluxing and heating the mixture at 90-100 degrees C for 24-48 hours, washing the heated mixture repeatedly and drying washed mixture to obtain oxidized-reduced graphene, where the ascorbic acid and crystalline flake graphite are in a mass ratio of 5-20:2; (2) graphene modified epoxy resin comprising 0.5-5 %mass graphene, epoxy resin, curing agent and accelerator, where the graphene comprises above-mentioned raw materials; and (3) method for preparing the graphene modified epoxy resin involves (A) preparing oxidized-reduced graphene by following above-mentioned steps from (a)-(c), (B) uniformly mixing epoxy resin, curing agent and accelerator with the oxidized-reduced graphene obtained in step (A) and ball milling the mixture to obtain graphene/epoxy resin mixture, where the oxidized-reduced graphene is 0.5-5 %mass with respect to the weight of epoxy resin, (C) stirring the graphene/epoxy resin mixture obtained in step (B) at room temperature to obtain epoxy/graphene prepolymer and (D) ultrasonically dispersing the epoxy/graphene prepolymer obtained in step (C) to obtain the graphene modified epoxy resin.