Under the influence of heat, the layers unfold like an accordion, and the graphite flakes expand. Depending on the material, the expansion already begins at 180°C and takes place suddenly and quickly. If the flakes can expand freely, their final volume is several hundred times greater than the initial volume.
The volume produced by the thermal expansion depends on the temperature during the process. As part of this, exfoliated packs are formed from graphite layers. Compared with the starting material, these have a very low bulk density and a significantly higher surface area, which predestines the product as an electrically conductive filler for batteries, plastics and ceramics.