分步插层法制备高倍膨胀石墨及其微观结构

Highly exfoliated graphite prepared by two-step intercalation and its microstructure

为获得密度小,漂浮性能好的膨胀石墨,采用分步插层法,依次以硝酸与磷酸的混酸、硝酸与乙酸的混酸为插层剂,高锰酸钾为氧化剂制备了高倍膨胀石墨。利用正交试验和平行试验确定了最佳工艺条件。在确定的工艺条件下制备出了膨胀体积为450ml/g的膨胀石墨。分析了用分步插层法制备高倍膨胀石墨的主要影响因素,提出其按影响大小依次为:第一步插层中高锰酸钾用量和第二步插层中乙酸、高锰酸钾和硝酸的用量。采用扫描电镜(SEM)分析了膨胀石墨微观结构随膨胀体积的变化。结果表明:随膨胀体积的增大,膨胀石墨片层被充分打开,几何截面增大,形成更大散射体,从而有利于红外辐射和毫米波的衰减。

To achieve exfoliated graphite with low density and good suspensibility,the mixture of nitric acid and phosphoric acid,and the mixture of nitric acid and acetic acid were employed as intercalating agents;potassium permanganate was used as oxidant,and highly exfoliated graphite was prepared by two-step intercalation.The optimum preparation conditions affecting expanding volume of the exfoliated graphite were determined by orthogonal and parallel experiments,then the exfoliated graphite with an expansion volume of 450ml/g was prepared with above special procedure.The effect factors on exfoliated graphite prepared by two-step intercalation was analyzed,and results point out that it is related to the amounts of potassium permanganate in the first intercalation and those of acetic acid,potassium permanganate and nitric acid in the second intercalation.Moreover,the microstructures of exfoliated graphite with different expanding volumes were also analyzed by Scanning Electron Microscopy（SEM）.The results show that as the volume expends,the layers of the exfoliated graphite are fully opened and its geological section area is increased to form a larger deflection entity.Therefore,it accelerates the decay of infrared and micro wave radiations.