摘要：为了研究石墨在机械剥离法制备石墨烯过程中剥离与团聚的力学性能,以天然超细石墨为原料,采用具有高剪切效果的机械剥离法,在无分散剂的去离子水介质中制备层数不超过5的石墨片体积分数为18.5%的石墨烯悬浮液;采用原子力显微镜、扫描电子显微镜和粒度分布测试仪表征被剥离的石墨片,获得被剥离石墨片的整体层数分布,并基于层间相互作用能计算石墨厚度变化过程中的剥离能与团聚能。结果表明:当研磨、剥离6 h时,层数不超过5的石墨片含量最多;石墨片层变化释放的团聚能是消耗的剥离能的4倍;石墨片层的剥离使层间接触面积被释放,导致团聚能被激活并不断增大;石墨层间范德华能是阻碍石墨剥离和导致团聚的主要能量,库仑能的作用十分微弱。

关键词：石墨烯；石墨；剥离；团聚；力学性能；机械剥离法

Abstract：To study the mechanical performance of delamination and aggregation of graphite by mechanical delamination method for preparing graphene,taking ultrafine natural graphite powders as materials,graphene dispersion was prepared in surfactant-free de-ionized water by mechanical delamination method with high shear efficiency,in which there were graphite sheets with volume fraction of 18.5% and layers less than 5. The delaminated graphite sheets were characterized by AFM,SEM,and particle size analyzer to get the whole layer distribution of the delaminated graphite sheets,which was used to calculate the energy of delaminating and aggregating in the variation process of graphite thickness based on the interlayer energy interaction. The results show that the highest yield of graphite sheets with layers less than 5 is achieved as milling and delaminating for 6 h. The energy released in aggregating graphite sheets is 4 times greater than that consumed in delaminating graphite sheets. The contact area of graphite layers is released by delaminating graphite sheets,leading to the release and increase of aggregation energy. The main energy hindering delamination of graphite and leading to aggregation is van der Waals energy between graphite sheets,while Coulomb energy is weak.

Keywords: graphene；graphite；delamination；aggregation；mechanical performance；mechanical delamination