Study of carbon-flax hybrid composites modified by fibre fluorination

Knowing that fibre reinforced polymers are sensitive to moisture through their interphases, carbon and flax fibres sized with Bisphenol A diglycidyl ether were fluorinated under a N₂/F₂ atmosphere. Because of differences in reactivity of gaseous F₂ between fibres and sizing, only the latter has been fluorinated, resulting in a covalent grafting of fluorine atoms onto the fibres, that has been evidenced by Infrared spectroscopy, and X-Ray Photoelectron Spectroscopy. Fluorinated fibres exhibit enhanced mechanical properties, as highlighted by tensile tests. Hybrid and non-hybrid composite materials were then fabricated with vacuum infusion process, using non-fluorinated and fluorinated carbon and flax fibres. Their hydrothermal behaviour and mechanical properties were investigated, in order to study the impact of both hybridisation and fibre fluorination on the composite properties. A better water resistance was observed for polymer materials reinforced with fluorinated fibres, whereas their mechanical properties were slightly lower than polymers reinforced with non-fluorinated fibres.