The graphene in these products is nanoplate graphene made from graphite. Manufacturing companies understand how to make graphene as powders and dispersions. However, handling these materials on an industrial scale presents some challenges.
Graphene products are low density materials, typically a 16 litre container would hold just 1kg of powder and dispersions are typically 4% solids. Powders are dusty and challenging to handle, dispersions are bulky and for every kg of graphene you would have to handle 25kg of dispersion.
So, it was with interest that I read a paper published in nature by a team at Northwestern University in the USA and the National Sun Yat-sen University in Taiwan. They have made a high solids graphene oxide ‘dough’ rather like plasticine or playdough. It has a solids content of 50% and can be thinned with water without the dust problems associated with powdered solids.
The process for making the dough is complicated and time consuming, taking several days, however the graphene oxide product does not contain any binders which means the product is free from potential contaminants.
There is a further development that is perhaps even more interesting. Graphene oxide can be reduced back to graphene. The team used hydrogen iodide (HI) as a reducing agent and made a hot-pressed graphene material.
The team found this material is isotropic, the material is made of randomly stacked nanoplates of graphene. This means it has similar values when measured in different directions. They called this new material graphenic glass. It is not the glass you and I know from everyday experience but more like a glassy metal.
This pressed graphene product has some interesting properties. Graphite for example has different electrical and thermal properties when measured across or along bedding planes. Graphenic glass has properties that are the same regardless of the direction of measurement It is also much harder than a comparable pressed graphite.
This graphenic glass is a new form of graphene, its properties have yet to be fully explored. This work shows that graphenic glass can be made in a pure form with no other additives. This means the quality of the material can be tightly controlled. This should make it a rather attractive material for the aerospace industry.