Abstract: This paper studied a new method for preparing no-sulfur content and expandable graphite bypotassium permanganate as oxidant and a mixture of acetic anhydride and 65% nitric acid as medium. Theoptimum conditions for preparing the expandable graphite are as follows. Weight ratio of graphite: aceticanhydride: 65% nitric acid: potassium permanganate is 1.0:0.8:0.5:0.07; reacting temperature, 30℃;reacting time, 40min. The expanded volume and nitrogen content of the expandable grwphite are 280m/gand 1.27% respectively. the end product, flexble graphite does not contain nitrogen. To date, similar report has not been seen in the literature.

Key words: sulfur-free and expandable graphite, preparation, acetic anhydride, 65% nitric acid