A new technology including semisolid phase maceration for preparation of low surphur expandable graphite is presented, in which potassium permanganate and concentrated sulphuric acid are adopted as blended oxidants and ferric trichloride as an inserting agent. The optimum conditions of the process are as follows: mass ratio of graphite to sulfuric acid, potassium permanganate and ferric trichloride=1 03 00 80 2; reaction temperature and time: 50 ℃ and 1 h . The expandable graphite has an expanded volume of 230 mL/g and S content of 0 48%. By treating the product with sucrose borate solution and heating the flexible graphite plates also have been obtained with tensile strength of 7 5 MPa and oxidation loss of 11%. It is a green technology.
