The Study Of The Surface Modification About Aramid Ⅲ Fiber By Friedel-crafts Reaction

The aramid III is a novel heterocyclic aramid fiber with more excellentcomprehensive performance than conventional aramid fiber. Though it is still in theresearch and development stage with little yield, it has a very broad applicationprospects. The surface condition of aramid III fiber has improved from traditionalaramid, but it is still very small surface active sites on the resin matrix infiltrationremains poor, so the early stage of the research about surface modification of thefibers on the future of the aramid III the large-scale application has a very importantpractical significance. Aramid fibers III contains a large number of molecular chainsbenzene, according to their molecular structural features, this paper using classicalorganic reactions the Friedel-Crafts alkylation reaction that grafted epichlorohydrinand Vice product in benzene on the surface of aramid III fiber. The conditions ofFriedel-Crafts are mild and the reaction is easy to carry out, moreover the process issimple and the surface of the fiber is easy to clean after the reaction. It provides a newidea and direction for the aramid fiber surface modification.According to the Friedel-Crafts alkylation reaction mechanism, this articledesigns the modified formula, and then determines the suitable treatment time at thereasonable reaction temperature. Before and after modification, the monofilamentstrength of the fiber and Monofilament pull out strength, the multifilament yarnstrength, laminated plate bending strength of the aramid III/epoxy composites areinvestigated, what decided whether the modification improved the mechanicalproperties of the matrix and fiber and also determine the best reaction time. Beforeand after modification, the SEM photos of aramid III fiber surface, monofilament pullinterface, multifilament tensile sections and the laminated plates sections areinvestigated, what determined whether the treatment enhance the interfacial bondproperties about aramid fiber III/epoxy composites. Before and after modification, theinfrared spectra, XPS spectra, specific surface area and the contact angle are studied,what evaluated whether the graft perfected the wettability between the fiber andmatrix.Studied the microscopic and macroscopic properties of aramid III/epoxycomposites before and after modification, the results showed that: the best treatment time about small quantities of aramid III tow is1h, the suitable modification time onlarge quantities of Kevlar III fabric is above2h. After modification, the strength ofaramid III monofilament has changed little, the monofilament pull out strengthincreased by49.5%, multifilament strength increased by about9.38%and the flexuralstrength of aramid III/epoxy composites increased by35.4%. There was a largenumber of resin on the fiber surface at the cross-section of the aramid III/epoxycomposites, and some fibers were partly torn into filaments, that significantlyenhance the interfacial adhesion properties of aramid III fiber and epoxy resin.Aramid III fiber surface area improved by34.48%, significantly increased theeffective contact area of the fiber and the matrix; the surface free energy and itscomponents were bigger, the dynamic contact angle becomes smaller, whicheffectively improved the wettability of the fiber surface. Meanwhile, the IR and XPSspectra before and after treatment showed that the epoxy chloropropane and itsbyproducts successfully grafted onto the fiber surface, the surface chemical activity ofthe aramid III fiber becomes larger.