Study On Chemically Modified Carbon Fibers/polypropylene Composites Properties

Polyacrylonitrile-based carbon fiber reinforced polymer compositeswith theirfavorable strength-to-weight and stiffness-to-weight ratiosare widely used in aerospace,automotive,wind energy and sports equipment fields.etc.However,after high-temperature carbonization process in theindustrial production process,carbon fiber(CF)will form smooth and inert surfacewith some grooved streaks distributed along the longitudinal direction,which causes poor physical and chemical interaction between CF and various resin matrices.Hence,before preparing high-performance CFreinforced composite materials,the CF must be modified by means of surface treatment modification to enhance the surface chemical activity or endow it a favorable morphography.Only in this way can the external force be effectively transmitted to the carbon fiber and make full use of the excellent properties of CF.Among the many modification methods of CF,chemical treatmentis one of the most potential modification technologies.In this paper,the focus of first work is to prepara the short carbon fiber(SCF)/polypropylene(PP)compositeswith excellent interfacial propertiesvia Friedel-Crafts polyalkylation.The preparation process of carbon fiber(SCF)/polypropylene(PP)composites convenient,with industrial production potential.The solution dipping method is adopted to modify the SCF surface by Al Cl₃ adhered uniformly.During the process of melting and mixing,Friedel-Crafts alkylation initiated by aluminum trichloride directly chemically grafts the polypropylene segment onto the inert CF surface,forming a marvelous interaction between CF and PP.After standard testing,the optimal results showed that the tensile,flexural and notched impact strength of the composites increased by 38.3%,57.3%and 93.6%respectively.In addition,the different loading qualities of Lewis acid also have beneficial effect in the thermal stability and crystallization temperature of SCF/PP composites.This paper also studied the one-step construction of multi-walled carbon nanotubes(CNTs)/graphene oxide(GO)multi-scale carbon fiber interface through the thiolene reaction between the silane coupling agent,and successfully prepared the composite material with polypropylene.The thiol-ene reaction initiated by ultraviolet light is green and efficient,and no by-products harmful to the environment are produced.Scanning electron microscope pictures proved that successful construction of multi-scale structures on the CF surface.And the changes of chemical functional groups on the fiber surface before and after modification were detected.The overall mechanical properties of the treated SCF/PP composites are tested by universal testing machines according to different standards.The experimental data also show that this method can significantly improve the mechanical properties of the composites.When the fiber content is 10 wt%,the tensile,flexural and impact strength of the modified composite are increased by 32%,51.8%and79.2%,respectively.