▎ 摘　　要

NOVELTY - Anti-water tree aging composite material comprises 0.002-0.01 wt.% graphene and 99.9-99.998 wt.% cross-linked polyethylene, where the number of layers of the graphene is 2 layers and its surface area is 450-500 m2/g. USE - The composite material is useful for preparing cable insulation layer (claimed). ADVANTAGE - The composite material inhibits the growth of water trees in the composite material, reduces the size of the water trees, improves the water tree aging resistance of the composite material, can quickly and accurately determine the size of the water tree in the material, and provides theoretical basis for the research and development of a new generation of water tree aging resistance materials. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a method for preparing anti-water tree aging composite material involving (i) mixing polyethylene and xylene at a material-to-liquid ratio of (40-50):(280-320) g/ml, and stirring at 90-120 degrees C until the polyethylene is completely dissolved to obtain initial solution, (ii) adding graphene to the initial solution, and ultrasonically vibrating for 1-2 hours to obtain suspension, (iii) drying the suspension at 75-85 degrees C to obtain mixed solid, (iv) mixing the mixed solid and cross-linking agent in a mass ratio of 100:(2-5), uniformly stirring at 120-130 degrees C, and cross-linking at 155-165 degrees C under 15-20 MPa for 30-35 minutes to obtain the initial product, and (v) placing the initial product in vacuum environment and degassing for 20-25 hours to obtain the product; and (2) a method for testing the composite material involving (a) preparing the composite material into a square sheet with side length of 50 mm and thickness of 3 mm, drilling 22-25 defective pinholes on the square sheet, (b) placing the processed square sheet obtained in step (i) in the performance test device comprising cup portion and base bolted to the bottom of the cup portion, and equipping the cup portion with cup cover, providing the cup cover with an upper electrode, which is connected to a high-frequency and high-voltage power supply, providing a through hole at the bottom of the cup body, and bottom electrode on the base directly opposite to the through hole, grinding the bottom electrode, filling the cup with sodium hydrochloride solution mass concentration of 20%, fixing the square sheet between the through hole and the lower electrode and defective pinhole directly opposite to the through hole, (c) controlling the output voltage of the high-frequency and high-voltage power supply to be 7-8 kV, and the output frequency to be 400-450 Hz under this condition, subjecting the square sheet to accelerated water tree aging treatment for 30 days, and (iv) slicing and dyeing the square slice, measuring the size of the water tree under an optical microscope to complete the test of the water tree aging resistance of the composite material.