混酸插层制备膨胀石墨研究

PREPARATION OF EXFOLIATED GRAPHITE BY INTERCALATING AGENTS OF MIXED ACID

对采用H2SO4-HNO3-KMnO4-H2O2混酸氧化插层体系制备膨胀石墨进行了研究，采用扫描电镜（SEM）、X射线衍射（XRD）、红外光谱（IR）和热重一差热法（TG-DTA）分析产物，并提出了氧化插层过程和机理。分析表明：插入剂的插入破坏了原有鳞片石墨层的紧密结构，使碳层间距增大，高温膨胀后，膨胀石墨呈蠕虫状或手风琴状蓬松结构，一个石墨蠕虫由许多微胞连接在一起组成，微胞之间呈现较大的狭缝裂开。氧化插层破坏了鳞片石墨原有的晶体结构，但是未破坏石墨的C—C键，20=29．5。处的特征峰是由石墨插层物结晶区引起的。可膨胀石墨片层。间存在SO4^2-、NO2阴离子插层物。可膨胀石墨在500℃之前的热失重和267℃附近较小的放热峰，均是由石墨插层物的气化、分解所致。

Study on preparation of exfoliated graphite was made using H2SO4 - HNO3 - KMnO4 - H2O2 mixed acid oxidation- intercalation system. The product was characterized by means of scanning electron microscopy （SEM）, X-ray diffraction（XRD）, infrared ray （IR）, thermal gravimetric and differential thermal analysis （TG- DTA） .At meantime, the oxidation- intercalation process and mechanism were put forward.Original structure of flake graphite layers was destroyed because of intercalation, and space between carbon layers increased.After high temperature expansion, exfoliated graphite composed of micro- cells was worm- like or accordion - like fluffy structure, and large slits existed between micro- cells.Crystal structure of flake graph- ite was damaged because of oxidation intercalation, but the C- C bond was not undermined.The peak 20 = 29.5°was due to crystalline of intercalation.Negative ion SO42-- and NO3- existed as intercalation compounds between graphite pieces.Weight loss of expandable graphite occurred before 500℃ and the small exothermic peak at 267℃ were due to gasification and decomposition of graphite intercalation compounds.