▎ 摘　　要

NOVELTY - Surface-modification of poly-p-phenylene-2,6-benzobisoxazole fibers involves adding poly-p-phenylene-2,6-benzobisoxazole fibers to a three-necked flask containing 100-500 ml concentrated nitric acid, stirring, reacting, cooling, taking out the poly-p-phenylene-2,6-benzobisoxazole fibers, washing using deionized water, and vacuum-drying to obtain carboxylated poly-p-phenylene-2,6-benzobisoxazole fibers, and dispersing 0.05-0.15 g modified graphene oxide in 40-100 ml N,N-dimethylformamide, ultrasonically-processing in a 400 W ultrasonic cleaner for 1-3 hours to obtain an uniform graphene oxide dispersion, adding 0.02-0.08 g carboxylated poly-p-phenylene-2,6-benzobisoxazole fibers, reacting by heating under reflux conditions for 24-72 hours under the protection of nitrogen, washing carboxylated poly-p-phenylene-2,6-benzobisoxazole fibers with N,N-dimethylformamide 1-7 times, and drying to obtain surface-modified poly-p-phenylene-2,6-benzobisoxazole fibers. USE - Surface-modification of poly-p-phenylene-2,6-benzobisoxazole fibers. ADVANTAGE - The method enables surface-modification of poly-p-phenylene-2,6-benzobisoxazole fibers using active functional groups on the modified graphene oxide surface which increases the roughness and specific surface area, and solves the problem of poor adhesion to polymer matrix caused by the lack of functional groups on the surface of the poly-p-phenylene-2,6-benzobisoxazole fibers due to the smooth surface. The surface-modified poly-p-phenylene-2,6-benzobisoxazole fibers have improved mechanical property. DETAILED DESCRIPTION - Surface-modification of poly-p-phenylene-2,6-benzobisoxazole fibers involves preparing (i) graphite oxide, adding 10 mg graphite oxide to 100 mL deionized water, ultrasonically-cleaning and stirring to dissolve in a 400 W ultrasonic cleaner, adding an appropriate amount of ammonia, adjusting the pH of the reaction system to 8-12, adding 0.1-1 g p-phenylenediamine to the reaction system, maintaining at a temperature of 70-120 degrees C, reacting for 1-10 hours under mechanical stirring, vacuum-filtering the reaction product and drying to obtain a modified graphene oxide, adding (ii) poly-p-phenylene-2,6-benzobisoxazole fibers to a three-necked flask containing 100-500 ml concentrated nitric acid, stirring, reacting at 100-500 rpm for 1.5-3 hours at 70-85 degrees C, cooling to room temperature, taking out the poly-p-phenylene-2,6-benzobisoxazole fibers, washing using deionized water to becomes neutral, and vacuum-drying at 80 degrees C for 5 hours to obtain carboxylated poly-p-phenylene-2,6-benzobisoxazole fibers, and dispersing (iii) 0.05-0.15 g modified graphene oxide in 40-100 ml N,N-dimethylformamide, ultrasonically-processing in a 400 W ultrasonic cleaner for 1-3 hours to obtain an uniform graphene oxide dispersion, adding 0.02-0.08 g carboxylated poly-p-phenylene-2,6-benzobisoxazole fibers, reacting by heating under reflux conditions for 24-72 hours under the protection of nitrogen, washing carboxylated poly-p-phenylene-2,6-benzobisoxazole fibers with N,N-dimethylformamide 1-7 times, until the obtained product is colorless and transparent, and drying to obtain surface-modified poly-p-phenylene-2,6-benzobisoxazole fibers. The addition amount of poly-p-phenylene-2,6-benzobisoxazole fibers is 1-10 %mass of the mass of concentrated nitric acid.