The silicon carbide (SiC) nanofibers (0.1, 0.25, and 0.5 phr), produced by self‐propagating high‐temperature synthesis (SHS), are used to reinforce the epoxy matrix cured with an anhydride hardener. Morphological studies reveal a better dispersion of SiC nanofibers and a good level of adhesion between nanofiber and the matrix in composites with lower (0.1 and 0.25 phr) nanofiber loading. The flexural studies show that a maximum increase in flexural properties is obtained for composites with 0.25 phr SiC nanofiber. The fracture toughness of epoxy is found to increase with the incorporation of SiC nanofibers, and 0.25 phr SiC nanofiber loading shows maximum fracture toughness value. The possible fracture mechanisms that exist in epoxy/SiC nanofiber composites have been investigated in detail. Thermogravimetric analysis reveals that SiC nanofibers are effective fillers to improve the thermal stability of epoxy matrix. Copyright © 2014 John Wiley & Sons, Ltd.

Epoxy/clay/carboxyl-terminated poly(butadiene-co-acrylonitrile) (CTBN) hybrids were prepared with two different organically modified clays. Octadecyl amine and trimethyl stearyl ammonium-modified nanoclays (Nanomer I.30E and I.28E, respectively) were used. The dispersion of the nanoclay in binary epoxy/clay and epoxy/clay/CTBN hybrid nanocomposites was investigated using scanning electron microscopy and optical microscopy, and the observed morphological details were explained by the prediction of solubility parameter for each component in the nanocomposites. The effect of clay modifier on cure characteristics of binary epoxy/clay and epoxy/clay/CTBN hybrid nanocomposites was studied using rheological analysis. Glass transition temperatures (T g ) and thermal stability of binary and hybrid nanocomposites were also measured. The reduced cross-link density via epoxy homopolymerization, the plasticizing effect of clay modifier/dissolved liquid rubber and the interfacial adhesion between the polymer and the clay platelets were found to affect the Tg of epoxy/clay/CTBN hybrid. In epoxy/clay/ CTBN hybrid, the thermal stability was mainly attributed to the presence of CTBN which hide the effect of clay modifiers.

Titanium dioxide (TiO2) nanotubes are considered to be unique in terms of their physical properties and high dielectric constant. The oxygen vacancies in TiO2 play a crucial role in the dielectric behavior, which can be tuned by doping with proper materials. Herein, the changes in the dielectric behavior, as well as defect concentration of TiO2 nanotubes by Cobalt (Co) doping, have been evaluated. For this purpose, Co-doped TiO2 nanotubes have been synthesized by using combined sol-gel and hydrothermal methods. By analyzing photoluminescence spectra, the intensities and positions of five emission peaks are clearly assigned. The PL peaks could be sensibly explained by various mechanisms, such as direct allowed transition, oxygen vacancies, and self-trapped excitons. The dielectric behavior of Co-doped TiO2 nanotubes with controlled oxygen vacancies is explained. The dielectric constant is particularly at its highest in higher Co-doped TiO2 nanotubes. The current investigation provides new insight into the mechanisms underlying the anomalous dielectric properties shown by Co-doped TiO2 nanotubes, as evident from the movement of oxygen vacancies. It demonstrates the influence of defect dipoles, 2CoTi—Vȯ••, in the anomalous dielectric behavior observed for Co-doped TiO2 nanotubes.