Study On Durability Of CNF/EP/Flax Fiber Composites In Hygrothermal Environment

Fiber Reinforced Polymer (FRP) is a new type of structural material which gets a lot of attention because of its lightweight, high strength, good corrosion resistance, easily construction and designed, it is widely used in civil engineering structural reinforcement and transformation. The durability in harsh environment is one of the most important factors affecting as a structural material in the promotion and application of civil engineering. Its durability depends on the rate of diffusion and absorption of water molecules in humid environment largely. Studies have shown that adding a small amount of the epoxy-based nano particles can not only improve their mechanical properties, but also reduce the level of equilibrium water absorption and diffusion coefficient largely. Based on this, this paper applied the method of high speed stirring to disperse the carbon nano fibers (CNF) into epoxy resin in nano scale in order to improve the mechanical properties of the resin matrix and reduce the water molecules diffusion rate of FRP composite materials. In this paper, we use green ecological flax fibers as reinforcing fibers of FRP, since it is wide variety of sources, relatively cheap and environmentally friendly. The main research content is as follows:First, comprehensive use high-speed mechanical stirring, vacuum and ultrasonic dispersion method for preparing CNF/epoxy nano composites, and use them to produced a CNF/epoxy base/flax fiber composites (FFRP) by a wet lamination process. Then study the mechanical properties of the composites, and the distribution morphologies of different contents CNFs in the resin particles with a scanning electron microscope.Secondly, place the different contents of CNF/epoxy nano composites in 23℃,40℃, 60℃ heat aging, then by test their equilibrium water absorption and diffusion coefficient to study the impact on water absorption and diffusion material after adding CNFs. And study the influence of water environment to their mechanical properties and the glass transition temperature by place the epoxy nano composite in 40℃ water for some time.Finally, place the CNF/epoxy base/flax fiber composites under three temperature heat aging, study the impact of water absorption and diffusion of FFRP composites. Study the mechanical properties of 40℃ water environment soaking wet heat aging, then by using scanning electron microscopy to observe the tensile fracture surface to revealing the CNFs distribution pattern in epoxy resin and flax fibers. The results showed that CNFs modified resin matrix can significantly improve the mechanical properties and durability of FFRP.