Performance Research Of Nano-carbon Materials/Epoxy Resin Composite Material

One-dimensional multiwalled carbon nanotubes (MWCNTs) and two-dimensionalgraphene are two kinds of very important carbon materials which are widely used as the fillerof composites. However, the agglomeration of MWCNTs and grapheme, as well as the weakinterfacial bonding between them and polymer matrix are the two main drawbacks whichgreatly affect them applied to composite materials. Herein, this thesis prepared grapheneoxide (GO) by a modified Hummers method and obtained MWCNTs treated with mixed acid.Then they were surface functionalized by grafting long-chain polymer onto their surface. Thedispersibility and interface bonding strength with epoxy resin were improved. After that, EPcomposites containing different fillers were produced through solvent blending method. Also,the influence of surface functionalization to their performances was further elucidated.Detailed process and the results are as follows.1The single-layer graphene oxide which contained a lot of oxygen-containing groupswas prepared by a modified Hummers method. The surface functionalization of GO wasdivided into two main processes: firstly, GO was surface modified with vinyl trimethoxysilane (A171) which contained carbon-carbon double bond to obtain Si-GO; secondly,methacrylic acid (MAA) was grafted onto the surface of Si-GO by solution polymerization.Fourier transform infrared spectra, thermal gravimetric analysis revealed that the surfaces ofGO were grafted assuredly with silane coupling agent and MAA. The N2adsorption-desorption isotherms of GO showed that the surface area of GO was326.7m2/gand the surfacial pore size distribution was uniform (around3-5nm). XRD and SEM photosindicated that the layers of GO have been separated and the layers spacing was0.961nm.Dispersibility test and water contact angle test results showed that the surfaces of GO weregrafted with polymer chains that contained carboxyl.2In order to get MWCNTs that contained carboxyl and hydroxyl, MWCNTs was treatedwith mixed acid. Then MWCNTs was surface functionalized using the same method of GOand functionalization of MWCNTs/EP composites were prepared. Fourier transform infraredspectra, thermal gravimetric analysis and dispersibility test results revealed that the surfacesof MWCNTs had been grafted with A171and MAA. TEM photos showed that functionalized MWCNTs dispersed uniformly and theirs diameter increased by12.9nm. This resultdemonstrated that the surfaces of MWCNTs were coated with a layer of polymer.3Dynamic mechanical analysis of functionalized GO/EP indicated that storage modulus(E’), loss modulus (E"), Tg, and tanδ of GO/EP composites gradually improved greatly withthe surface modification of GO. The surface functionalization of GO had great influences onthe damping properties of composites. Mechanical property tests show that the functionalizedGO could improve the mechanical properties of the EP because the interfacial strength anddispersibility were improved.4Dynamic mechanical analysis of functionalized MWCNTs/EP composites indicatedthat functionalized MWCNTs could significantly improve the damping properties ofcomposites in high temperature zone. The damping properties of composites containeddifferent contents of functionalized MWCNTs indicated that effective damping temperaturerange and high performance damping temperature range of composites moved to the hightemperature region with the increased addition of functionalized MWCNTs. Tgand tanδincreased by10.1℃,52%than that of pure EP, respectively, as the addition amount offunctionalized MWCNTs was4%. Mechanical properties tests showed that elasticity modulusand tensile strength increased by60.47%and51.51%, respectively. Comparing reinforcingeffects of Si-MWCNTs and p-MWCNTs found that the dispersibility and interface bondingstrength had great influence on mechanical property.5Damping property and mechanical property of functionalized (GO+MWCNTs)/EPcomposites showed that the blend of one-dimensional MWCNTs and two-dimensional GOcould improve their dispersibility due to mutual isolation. The synergistic effect couldsignificantly improve the damping property and mechanical property of composites. Theeffect was superior to simple structure filler.