Study On Microstructure And Performance Of Carbon Nanotube/Carbon Fiber Multiscale Reinforcement

Carbon fiber (CF) reinforced plastic has been used widely in fields ofspaceflight and aviation. Composite pressure vessel is more and more popularthan metal one because of its light weight, high strength, and leak-before-breakproperties. However, carbon fiber reinforced polymeric composite is subjected tomatrix crack, poor interfacial bonding and low shear strength. Therefore, theunique mechanical properties of carbon fiber can't be fully realized in itscomposite, which affect the integral properties of the composite in sequent.In view of the interfacial performance improvement between carbon fiber andthe resin system, this paper presents a new chemical method usedfor preparationof the CNT/carbon fiber multi-scale reinforcement (MSR), which combinesmicrometric fibers with nanometric CNTs. Multi-walled carbon nanotubes(MWCNTs) functionalzized with hexamethylene diamine (HMD) at the end capsare grafted onto the surfaces of carbon fibers treated with acyl chloride using thefiber surface grafting technique. The MSR was prepared to improve the wettingquality and the interfacial strength, make full use of the mechanical performanceof carbon fiber and consequently improve the integral performance of thecomposite. Chemical modification of carbon fibers, chemical functionalization ofcarbon nanotubes and preparation and analysis of the MSR were stressed in thisresearch.Chemical functionalization of MWNCTs and surface chemical treatment ofcarbon fibers were studied in detail. On this basis, The MSR was prepared bygrafting CNTs onto the fibers. The surface element concentrations, surfacefunctional groups and morphology of the MSR were examined by X-rayphotoelectron spectroscopy (XPS), infra red spectrum (IR), scanning electronmicroscopy (SEM) and transmission electron microscopy (TEM). Ramanspectrum was employedto determine the changes of microcrystal structure of thecarbon fiber and the MWCNT. Finally, the mechanism of the MSR was predictedtheoretically. The prepared MSR makes it possible to make full use of theexceptional high stiffness and toughness both of carbon fibers and CNTs in theircomposites.