Preparation and Affecting Factors of Expandable Graphite

In traditional method,expandable graphite is always prepared by flake graphite,H_2SO_4,HNO_3 and K_2Cr_2O_7.In this paper,the conditions for preparing the expandable graphite were optimized by orthogonal test method based on the direction of traditional technique,and factors effecting expansion volume were obtained.The results indicate that expandable graphite with low pollution can be prepared without HNO_3.It could be produced under the optimum conditions with the following weight ratio:flake graphite:H_2SO_4:K_2Cr_2O_7=1:4.92:0.10,re- action time:30min,and reaction temperature:30℃.The expansion volume can be reached 260ml/g.