Method of Forming Graphene Nanoplatelets, Graphene Nanoplatelets So-Obtained and Composites Comprising Said Nanoplatelets

Provided is a method of forming graphene nanoplatelets, comprising: providing an aqueous suspension comprising expanded graphite; and subjecting the suspension to exfoliation, wherein the exfoliation comprises sequential treatments of sonication and high shear mixing, thereby forming graphene nanoplatelets. Also provided is a method of forming an expanded graphite, comprising obtaining an expandable graphite and heating the expandable graphite in flowing gas at a temperature of at least 600°C. Also provided are graphene nanoplatelets obtainable or obtained by the said method of forming graphene nanoplatelets, a plastics composite comprising the graphene nanoplatelets, a vehicle or structure comprising such a composite, and use of such graphene nanoplatelets in a plastics composite