In-situ Click Polymerization On Carbon Fiber Surface And Research Of Interfaces Properties Of Composite Materials

Carbon fiber reinforced epoxy matrix composites are widely used in defense military industry,construction industry,transportation,medical equipment and other fields,owing to their excellent characteristics,such as light weight,high strength,high specific modulus,good stability and corrosion resistance.The performance of the composites is affected by the interface between carbon fiber and epoxy matrix.However,due to the smooth surface and lack of reactive functional groups,carbon fiber exhibits chemical inertness,which leads to poor interface adhesion.Therefore,it is necessary to modify the surface of the carbon fiber.Up to now,a variety of methods have been used to modify the surface of carbon fibers,their aim is to introduce reactive functional groups on the surface of carbon fibers or increase the surface roughness of the carbon fibers,thus it can improve the interfacial adhesion strength between carbon fiber and epoxy matrix.Among them,the introduction of POSS,carbon nanotubes,micro-nano particles and other materials on the surface of the carbon fiber can not only change the surface composition,but also increase the surface roughness of the carbon fiber to a large extent.In the previously reported methods of surface modification of carbon fibers,most of the pretreatment is mainly oxidized by strong oxidant,which will damage the strength of carbon fiber itself.And,the surface morphology of carbon fiber can't be flexibly adjusted.Therefore,the research idea of this thesis is proposed:thiol-epoxy click particles are in-situ grown on the surface of carbon fibers by click polymerization,to improve the surface roughness and wettability of carbon fibers.Thus,it can improve the interface bonding strength between carbon fiber and epoxy matrix.Besides,the process and mechanism of in-situ growth on the surface of carbon fiber is also been explored.The main research contents are described as follows:1.In-situ growth of thiol-epoxy click particles on the surface of carbon fiber:Firstly,dopamine is used to pretreat the carbon fiber to introduce the active functional groups.Then,in isopropanol solution,tetra(3-mercaptopropionic acid)pentaerythritol ester(PETMP)or trimethylolpropane tris(3-mercaptopropionate)(TMPMP)and trimethylolpropane triglycidyl ether(TMTGE)are selected as click monomers to in-situ grow click particles on the surface of carbon fibers.And the influence of the amount of click monomers on the surface morphology,chemical composition,contact angle of carbon fiber surface and the adhesion strength of the interface when compounded with epoxy resin are also been investigated.2.Research on the mechanism of click particles in-situ growing on the surface of carbon fiber:Through SEM observation,FTIR analysis,XPS analysis,weight gain rate of carbon fiber and monomer conversion rate analysis,the surface morphology and composition of carbon fiber during the in-situ growth of click particles are showed,to reveal the mechanism of in-situ growth of click particles on the surface of carbon fibers:after pretreated by dopamine,the active site on the surface of carbon fiber reacts with the click monomer,and then forms a layer of cohesive polymer by click reaction between the monomers.As the molecular weight of the click polymer increases,the polymer begins to curl up and form a layer of small protrusions.Then,the protrusions gradually grow to form a layer of polymer particles on the surface of carbon fiber.3.In-situ growth of three-component particles on the surface of carbon fiber:By using polyetheramine D230 as the third monomer,a layer of core-shell particles was grown on the carbon fiber surface by two-step feeding method.The thiol-epoxy-amino particles are in-situ grown on the surface of the carbon fiber by one-step feeding method.Thiol group or epoxy group as the third component is added to the thiol-epoxy two system,to perform in-situ click polymerization on the surface of the carbon fiber.By changing the monomer type,monomer ratio and feeding method of the third component,the surface morphology,chemical composition and interface properties of the carbon fiber can be adjusted.