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