Study On The Structures/Properties Of Carbon Fibers And Their Reinfroced Resin Composites

The properties of domestic carbon fibers have been higher than before throughquicklily developing for decades. In order to promote domestic carbon fibers to play animportant role in civil engineering, this paper has studied the surface structure andpropertis, preparation process and carbon reifoced composites comprehensively. First,mechanical propertis and surface wetting of carbon fiber comprehensively, and theresults give the features of domestic carbon fibers through comparing with importedcarbon fibers. Carbon Fiber Reiforced Polymer (CFRP) was produced throughpultrusion process with different carbon fibers. The mechanical properties of CFRPwere tested, and the relationship between mechanical properties, thermodynamicspropertis and process parameterswas studied. All the studies in this paper will provideexperimental and theoretical foundation for producing advanced CFRP.The main studies and conclutionsin this paper:1. All the factors of the monofilamenttensile test method have been studiedsystematacially, and the result shows that tensile strength is sensitive to typesofadhesive, tensile length and cure time of adhesive. The stable test method was alsoestablished.2. The mechanical propeties of the domestic carbon fibers were testedwith themonofilament tensile test method, and the tensile strenth was evaluated by Weibullfunction. The result shows that the properties of domestic carbon fibersare lower thanimported carbon fibers. The surface structure of single carbon fiber was observedthrough Scanning Electron Microscope (SEM) test and Atomic Force Microscope(AFM) test, and the results reveals that there are more nicks and grooves in the surfaceof domestic carbon fiber than imported carbon fiber, which may been one reason forcausing the properties of domestic carbon fibers poorer.3. Comparing with imported carbon fibers, the domestic carbon fibers has morebreaken filaments and seriously fluff, meanwhile, the external diameter of carbon fiberis more discrete.4．The contact anglesbetweendiffetent kinds epoxy resins and fiberswere tested, andthe surface energy of carbon fibers wasalso tested by liquid drop method. The testresults indicate that different epoxy resin need different kind fibers to get the bestwetting properties; the surface energy of demostric carbon fibers waslittle bigger thanTokey carbon fibers; The sizing agent can improve fiber surface properties of carbonfibers.5．CFRP sheets were produced through pultrusion process with different processparameters, and the thermodynamics properties were studied systematacially. Throughthe studies, the relationships between mechanical properties, internal structure and process parameters were confirmed, The test results also show that the FRP sheets madeby domestric carbon fibers are much loerer than those made by imported carbon fibersin tentile, flexion and interminal shear propertis. For19kinds of CFRP sheets, SFF(Simultaneous Fiber-Failure) model is not precise to predicate the tentile strenth, whilemixed modelcan provide a credible tentile modul,furthermore, different processparameters affect the thermodynamics properties a lot.