Check out the paper given below:

Graphene-based composite materials.

http://www.ncbi.nlm.nih.gov/pubmed/16855586

Check this  paper (composite based carbon nanotube)

Article Improving the current density J(SC) of organic solar cells P...

The mixing procedure depends on the matrix, the compatibility between graphene as a filler and the matrix is the key factor to determine the mixing procedure.

I did it with Al matrix. I mixed the graphene using ball milling. here is the link of the paper.  it is a very promising technique for mixing graphene or any other graphetic structure materials. http://www.sciencedirect.com/science/article/pii/S1359836813007737

Please contact Prof. Lawrence Drzal at Michigan State University about your question. He is an expert in exfoliated graphene nano-platelets, and mixing them with polymer resins. He should be able to give you a detailed answer to your question. His email is [email protected].

Thanks to all for giving relevant information.

Regards

Niranjan

graphene is exfoliated. Do you mean graphite?