In order to improve the flammability, and meanwhile increase the toughness of epoxy resin (EP), a flexible siloxane chain containing phosphaphenanthrene structure (KHDOPO) was chemically grafted onto epoxy resin macromolecules. Because of the polar phosphaphenanthrene group and the flexible siloxane chain interacting with the matrix, this modified epoxy resin (KHDOPO-EP) exhibited satisfactory flame retardancy and thermal stability. The thermal degradation and fire behaviors of KHDOPO-EP were systematically evaluated by thermo-gravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning (UL-94) and cone calorimeter (CC) tests. The results showed that KHDOPO-EP achieved V-0 rating in UL-94, with the LOI value of 33.1%. Furthermore, the introduced flexible siloxane chain effectively maintained the toughness of the flame retardant EP, whose tensile strength and impact strength were as high as 71.7 MPa and 15.56 kJ/m² respectively, much higher than those of neat EP, showing the characteristics of simultaneous toughening and strengthening. As an efficient flame retardant and flexibilizer, KHDOPO-EP possesses promising prospect in modification field of EP material.

为了改善可燃性，同时增加环氧树脂（EP）的韧性，将含磷菲结构的柔性硅氧烷链（KHDOPO）化学接枝到环氧树脂大分子上。由于极性磷杂菲基团和柔性硅氧烷链与基质相互作用，该改性环氧树脂（KHDOPO-EP）表现出令人满意的阻燃性和热稳定性。通过热重分析（TGA），极限氧指数（LOI），垂直燃烧（UL-94）和锥形量热仪（CC）测试，系统地评估了KHDOPO-EP的热降解和着火行为。结果表明，KHDOPO-EP在UL-94中达到V-0等级，LOI值为33.1％。此外，引入的柔性硅氧烷链可有效保持阻燃剂EP的韧性，分别比纯净EP高²，显示出同时增韧和强化的特性。作为一种高效的阻燃剂和增韧剂，KHDOPO-EP在EP材料的改性领域具有广阔的发展前景。