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This study was focused on the comparative effect of tube- and sheet-like nanocarbons on the structure–property relationships of fiber-reinforced composites. Graphene nanosheets and multi-walled carbon nanotubes (MWCNTs) were dispersed into commercial glass fiber fabric (Gf) to obtain multiscale graphene-Gf- and MWCNT-Gf-reinforcing materials, respectively, followed by a vacuum-assisted resin infusion process. The influence of MWCNTs and graphene on the mechanical and thermal performance of multiscale composites were investigated. The experimental results indicated that oxidized MWCNTs or graphene could ensure excellent dispersibility on the fiber surface, and ultimately enhance the mechanical properties and thermal stability of the resultant composites. Graphene oxide (GO), with a wrinkled and roughened texture, was shown to be superior to MWCNTs in terms of toughening the fiber/matrix interface and delaying the deformation or failure of the epoxy matrix. Under the same dosage of nanocarbons, the interlaminar shear strength of GO-Gf-reinforced composites (GO-GfCs) was raised by approximately 12%, and the relevant onset thermal-decomposition temperature was increased by > 11℃, compared with carboxyl MWCNT-Gf-reinforced composites (Mc-GfCs). Meanwhile, the GO-GfCs exhibited superior static and dynamic mechanical properties compared to those of Mc-GfCs.

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To improve the flame resistance of polystyrene, three kinds of organophilic heterionic montmorillonites (Na-montmorillonite, Ca-montmorillonite, and Fe-montmorillonite) reinforced polystyrene nanocomposites were prepared by melt dispersion method. The structure and composition of the organo montmorillonites were characterized by using X-ray diffraction and Fourier-transform infrared analysis. The adhesion between organo montmorillonites and polystyrene was investigated by scanning electron microscopy. The flame resistance and thermal stability of the polystyrene/organo montmorillonites were evaluated by cone calorimeter test and thermogravimetric analysis. The interlayer space of organo montmorillonites increased with the increase of the oxidation state of the cations. With the addition of organo montmorillonites, the peak values of all the flame resistance indexes of the polystyrene/organo montmorillonites nanocomposites decreased, among which the PHRR values have decreased the most, compared with those of polystyrene. Their corresponding test times have all been delayed following almost precisely the same trend. Therefore, their flame retardant ability come from their lamellated structures, their charring forming abilities, and the reducing power of Fe3+ in polystyrene/Fe-montmorillonite. Organo montmorillonites mainly act as a kind of intumescent flame retardants. The flame resistance of polystyrene/Na-montmorillonite nanocomposite was the best, and the polystyrene/Ca-montmorillonite came second, which is slightly better than that of polystyrene/Fe-montmorillonite.

To exploit the application of calcium montmorillonite (CaMt) and improve the flame resistance of polystyrene (PS), two kinds of long carbon chain quaternary ammonium bromides with different spatial effect (i.e., cetyltrimethyl ammonium bromide (CTAB) and didodecyl dimethyl ammonium bromide (DDAB)) were used to intercalate CaMt for yielding corresponding organic calcium montmorillonite (CaOMt). The PS nanocomposites containing CaOMt (PS/CaOMt) were prepared by melt blending method. The effects of CaOMt on flame resistance, thermal stability, tensile properties and interfacial adhesion of PS/CaOMt were investigated. The results showed that both CTAB and DDAB were intercalated into CaMt to get CaOMt with an exfoliated/intercalated structure, which could endue good interfacial adhesion and thermal stability for PS/CaOMt. All peak values of flame resistance parameters of PS/CaOMt decreased and corresponding combustion times were postponed obviously. Moreover, Young’s modulus of DDAB-intercalated PS/CaOMt was improved by 49.1% while its tensile strength kept at the same level as PS.