  The resistance to failure through tearing is a crucial mechanical property
for the application of different elastomers. In this work, graphene
nanoplatelets (GNPs) were introduced into a fluoroelastomer (FKM) matrix with
the aim of improving its tear resistance. The fracture energy through tearing
was evaluated using the pure shear test. It was found that the tearing energy
increased linearly with the volume fraction of the GNPs. At the maximum GNP
content, the tearing resistance was 3 times higher, suggesting efficient
toughening from the GNPs. Theoretical analysis of the micromechanics was
conducted by considering debonding and pull-out of the nanoplatelets as
possible toughening mechanisms. It was determined quantitatively that the main
toughening mechanism was debonding of the interface rather than pull-out. The
formation of cavities at flake ends during the deformation, as confirmed by
scanning electron microscopy, was found to contribute to the remarkably high
interfacial debonding energy (~1 kJ/m2).
