Polypropylene (PP) can be a substitute for XLPE due to its excellent electrical properties and recyclability. However, polypropylene has poor toughness and cannot be directly used for cable insulation. Elastomers can be used to relieve polypropylene toughness, making it a great potential for high-voltage (HV) cables. However, after composited with elastomer, the water tree resistance of PP is reduced, which cannot meet the requirements of high-voltage cables. MAH is used to inhibit water tree. In this paper, POE-g-MAH was prepared to improve the anti-water tree ability of composites.The water blade electrode method was applied to accelerate water tree aging of PP, POE, POE/PP and POE-g-MAH/PP specimens, and their morphology were observed by using optical microscope. The stress-strain characteristics of specimens are obtained by tensile test.Water tree growth properties verify that PP represents the superior anti-water tree ability, while its water tree resistance will be deteriorated after adding POE. Compared with the unmodified composites, the anti-water tree performance is enhanced after introduced POE-g-MAH. The stress-strain characteristics verify that the hardening index is PP, POE and POE/PP in descending order.The addition of POE has a negative impact on PP crystallization, result in the serious water tree ageing by providing channel. The composites have a low hardening index, density of tie molecular chains decreases in the amorphous region. Under the action of electric field, micro droplets can prefer to attach the lamella gap and form water tree. After graft MAH, the hydrophilicity of carbonyl group in MAH prevents water molecules from forming micro water droplets in the amorphous region. MAH can be grafted to improve water tree resistance.If needed, please include a figure or a table or an image with a caption here.

water tree;POE/PP;mechanical property;MAH