Allyl-Functionalization enhanced thermally stable graphene/fluoroelastomer nanocomposites

- Graphene with different functionalization groups were synthesized to incorporate into fluoroelastomer during free radical vulcanization.
- The thermal stabilities of these functionalized graphene were studies to select the suitable functionalization for rubber vulcanization which involving high temperature curing process.
- The allylamine groups on the graphene improved the vulcanization behaviors and the reaction order studied by vulcanization kinetics.
- The reduced allylamine functionalized graphene/fluoroelastomer not only shows enhanced modulus during tensile test, but also presents improved tensile strength as well as high temperature performance from 25 °C to 175 °C.

Development of new elastomers with novel functionality has continued since their discovery in order to meet industrial and defense needs in harsh environments. The recent advance of carbon nanomaterials inspired innovative material design strategies and enable more effective production of high-performance elastomers. In this paper, the free radical initiated crosslinking reaction in graphene/fluoroelastomer nanocomposites was studied and the effects of chemical functionalization of graphene nanosheets were analyzed. It indicated that graphene oxide (GO) enhanced fluoroelastomer nanocomposites demonstrated poor high-temperature stability due to the pyrolysis at around 200 °C. In contrast, reduced graphene oxide (RGO) enhanced fluoroelastomer exhibited good thermal stability, but RGO didn't participate in the crosslinking, resulting in very limited improvement in mechanical properties. In this paper, reduced allyl functionalized graphene was studied for the first time to enhance free radical initiated elastomers. The reduced allyl functionalization of graphene was demonstrated to impart superior thermal stability and enhanced mechanical properties to the elastomer matrices. The study of vulcanization kinetics provided insights that the allyl functional groups participated in and accelerated the crosslinking. These results indicated a scalable method to incorporate the advantages of graphene into polymer matrices through free radical reaction. The discovery is very promising to be used in the industry to fabricate gaskets, o-rings, and membranes for high temperature applications.

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