▎ 摘　　要

NOVELTY - Preparation of graphene-poly(p-phenylene benzobisoxazole) (PBO) composite fiber comprises vacuum heating graphene/PBO polymer, vacuum defoaming; placing obtained spinning solution under conditions of 180-200 degrees C and 2-5 MPa, passing through 5-10 layers of 80-800 mesh filter screen, and passing filtrate through spinneret plate to obtain filament; wire drawing, carrying out coagulating bath treatment, winding around plastic roller, soaking in flowing deionized water, and placing under vacuum. USE - Method for preparing graphene-PBO composite fiber (claimed). ADVANTAGE - The composite fiber has tensile strength of 3.8-4.2 GPa. DETAILED DESCRIPTION - Preparation of graphene-poly(p-phenylene benzobisoxazole) (PBO) comprises: (A) heating graphene/PBO polymer to 160-200 degrees C and under vacuum degree of 0.09-0.10 MPa, vacuum defoaming for 12-72 hours; (B) placing obtained spinning solution under conditions of 180-200 degrees C and 2-5 MPa, passing through 5-10 layers of 80-800 mesh filter screen, and passing filtrate obtained through spinneret plate of aperture 0.15-0.5 mm to obtain filament; and (C) wire drawing filament obtained with air-gap length of 10-50 cm and stretching ratio of 50-120, carrying out coagulating bath treatment at 60-70 degrees C, winding around plastic roller, soaking in flowing deionized water for 72-75 hours, and placing under vacuum condition and at 60-70 degrees C keeping for 8-12 hours. The spinning solution of graphene/PBO polymer is prepared by weighing graphene-containing monomer and polyphosphoric acid at mass ratio of 1:1.3-2, placing into kneader at 30-80 degrees C, stirring under vacuum and under the protection of nitrogen for 2-3 hours, raising temperature at rate of 10-11 degrees C/hour to 100-120 degrees C, stirring for 4-5 hours, controlling stirring rotating speed at 45-60 revolutions per minute (rpm) to obtain first mixed solution; adding phosphorus pentoxide to mixed solution at weight ratio of 1.2-1.5:1, raising temperature to 140-160 degrees C under the protection of nitrogen, keeping for 2-10 hours to obtain second mixture; adding second mixture into kneading machine, raising temperature to 180-200 degrees C, controlling rotating speed at 35-45 rpm, and maintaining for 4-5 hours. The graphene-containing monomer compound is prepared by weighing terephthalic acid and 0.25-4 mol/L sodium hydroxide (NaOH) at mass ratio of 1:2-2.1 to obtain terephthalic acid sodium hydroxide aqueous solution; preparing graphene oxide by modified Hummer method, dispersing graphene oxide in deionized water at dispersion frequency of 40-50 kHz and dispersing for 30-40 minutes to obtain 0.27-1.00 g/L graphene oxide aqueous solution; uniformly mixing graphene oxide aqueous solution and terephthalic acid sodium hydroxide aqueous solution at volume ratio of 1:0.5-1, heating to 40-60 degrees C to obtain mixed solution; dissolving 4,6-diaminoresorcinol dihydrochloride in deionized water under nitrogen atmosphere to obtain 0.125-2 mol/L 4,6-diaminoresorcinol dihydrochloride aqueous solution; and mixing mixed solution and 4,6-diaminoresorcinol dihydrochloride aqueous solution at volume ratio of 1:0.2-0.5, heating to 70-95 degrees C under the protection of nitrogen, keeping for 10-30 minutes, cooling to room temperature, filtering, obtaining filter cake, placing filter cake at conditions of 50-60 degrees C and vacuum degree of 8-10 Pa for 24-48 hours, where phosphoric acid mass content is 81-84%.