Fire protection performance of oxidized graphite modified with boric acid

We have studied intercalation in the graphite-H2SO4-H3BO3-K2Cr2O7 system with the acids in the weight ratio 1: 0, 12: 1, 6: 1, or 3: 1. The results demonstrate that, with decreasing sulfuric acid (active intercalant) concentration in solution, the stage number of the resultant graphite intercalation compounds increases. Boric acid modification raises the oxidation onset temperature of oxidized graphite by 200–300°C and improves its fire protection performance, with little or no effect on the bulk density of exfoliated graphite.