Functionalized sp2 carbon allotropes as fillers for rubber nanocomposites

In this chapter, functionalized sp2 carbon allotropes, as reinforcing fillers for rubber compounds, are discussed. This topic would probably require a whole encyclopedia if treated in all its details. Hence, a selection of only some aspects has been made and a summary of the most relevant features is proposed. Carbon black (CB), carbon nanotubes (CNT), graphite and graphene related materials (GRM) are considered as the carbon allotropes.The chapter is organized as follows. After a brief introduction on sp2 carbon allotropes, the reasons why they are used as reinforcing fillers in rubber compounds are summarized. The need for functionalization is then discussed. Prior art available for the functionalization of the cited carbon allotropes (CB, CNT, GRM) is summarized, with reference to: procedures of functionalization, features of the products, application in rubber compounds. Finally, innovative functionalization methods developed by the authors are presented and some results obtained in rubber compounding are discussed.