Effect of the microstructure on the intercalation and exfoliation behaviour of graphite

The process of the preparation of graphitic nanoplatelets via chemical intercalation and thermal exfoliation of graphite was considered. The dependence of the properties of the final product on the microstructure of the raw material and on different process parameters was analyzed. It is shown that the microstructure of the raw material has considerable influence on the structural transformations during the different preparation steps. The observed differences can be understood assuming that intercalation is initiated at the edges of graphite crystallites by the formation of intercalate nuclei. Essential differences of the nucleation time appear for unequal types of microstructure and give rise to different intercalation states. It is also shown that the sub-process of washing and drying the samples after intercalation is most critical and has significant influence on the characteristics of the final products. The results suggest that graphite fibres with sub-micron diameter and orientation of the crystallographic c-axis along the fibre axis will be particularly favourable for the preparation of graphitic nanoplatelets.