Tribological and mechanical performances of newly developed eco-epoxy composites incorporating flax fibres and graphene nanoplatelets

The inclusion of both fibre and solid lubricants into polymers may provide a potential solution to maximise their tribological and mechanical performances. This study investigates the effect of incorporating flax fibres and graphene nanoplatelets (GNPs) reinformcements in epoxy matrix composites on their tensile, microhardness and adhesive wear behaviour. Dry adhesive wear experiments were conducted using a block-on-ring (BOR) test rig against a stainless steel ring. Adhesive wear performance was evaluated considering the effect of the volume fraction (V- f ) of flax fibre (0, 15, 20 and 25 V- f .%) and different weight fractions of GNPs (1.5 and 3 wt.%). Different applied loads in the 15-60 N range, covering the mild and severe wear regions, were used. The worn surfaces were examined using a scanning electron microscope (SEM). The results revealed that flax fibre potently improved the stiffness and tensile strength of epoxy. Increase in V- f of flax fibre showed a positive tendency to improve the wear resistance of epoxy; however, with an insignificant change in the coefficient of friction (COF). More interestingly, heat distortion temperature (HDT) was found to be the main key parameter controlling the wear behaviours of the composites. SEM observations indicated that severe wear signs - including detachment, fragmentation and fibre debonding - were noted when the interface temperature reached the heat distortion temperature of the epoxy. On the other hand, the inclusion of GNPs reduced the interface temperature during sliding as well as the COF of the flax/epoxy composite. Ultimately, incorporation of flax fibres and GNPs enhanced both mechanical and tribological performances of the eco-composites.