Identical steady tribological performance of graphene-oxide-strengthened polyurethane/epoxy interpenetrating polymer networks derived from graphene nanosheet

Graphene-oxide-hybrided polyurethane/epoxy interpenetrating polymer networks (PU/EP IPNs) are prepared through an in-situ polymerization. The results showed that the mechanical performance of graphene-oxide-hybrided PU/EP IPNs is improved due to the formation of chemical bonds between graphene oxide nanosheet and polyurethane/epoxy segments, affording the loading transfer from polymer matrix to graphene oxide nanosheet The average friction coefficient in the steady stage is decreased about 30.2% from neat PU/EP IPN to graphene-oxide-hybrided PU/EP IPNs. Especially, the specific wear rate is decreased about two orders of magnitude from neat PU/EP IPN to graphene-oxide-hybrided PU/EP IPNs. Interestingly, graphene-oxide-hybrided PU/EP IPNs have the same friction coefficient in the steady stage, independent of graphene oxide content. The identical steady friction coefficients are derived from the same friction bodies in three-body friction model, such as grapheneoxide-strengthened PU/EP IPN surface, metallic counterpart and graphene-oxide-wrapping polymer particles as wear debris in the transfer film. (C) 2015 Elsevier Ltd. All rights reserved.