Method for preparing highly flame retardant expansible graphite

The invention provides a method for preparing highly flame retardant expansible graphite, relates to a method for preparing the expansible graphite, and aims at solving the problem that the expansible graphite has an inert surface, and is difficult to be effectively compounded with other materials, in particular polymer materials. The method comprises the following steps of: 1, preparing expansible graphite with carboxyl on the surface; 2, preparing acyl chlorinated expansible graphite; 3, preparing OH-POSS/expansible graphite copolymer; and 4, preparing the highly flame retardant expansible graphite. According to the method, silicon element, nitrogen element, phosphor element and carbon are organically combined, so that the flame retardant is good in synergy and compatibility; melamine and expansible graphite are subjected to chemical bond combination, so that the synergetic flame retardant capability of the melamine and expansible graphite can be remarkably improved; and the preparation method is simple, low in cost, single in synthesizing solvent, is easy to recycle and utilize, and facilitates scale production, so that the method has a good application prospect. The method can be used for preparing highly flame retardant expansible graphite.