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Since electrostatic self-assembly carbon nanotubes–carbon black (CNTs–CB) composite fillers have good electrical conductivity and an easy dispersion process, they were incorporated into epoxy matrix to fabricate the CNTs–CB/epoxy nanocomposites. The mechanical properties, electrical conductivity, piezoresistivity, as well as microstructure characterization of the CNTs–CB/epoxy nanocomposites were experimentally investigated. The piezoresistive mechanisms of the CNTs–CB/epoxy nanocomposites were also established based on tunneling conduction and contacting conduction. The significant improvements in compressive yielding strength and elastic modulus of the nanocomposites could be attributed to the stable interfacial interaction. A moderate percolation threshold was obtained at 0.41 vol% for the CNTs–CB/epoxy nanocomposites in comparison with that of the nanocomposites filled with only CNTs or CB particles. In monotonic compressive loading, the CNTs-CB/epoxy nanocomposites exhibited highly sensitive and remarkably non-monotonic piezoresistive responses, which could be divided into three stages and showed dependence on the distinct evolution of hybrid conductive networks under compression. Moreover, the experimental results of cyclic loadings confirmed the stability, repeatability, and recoverability in piezoresistive responses of the nanocomposites. Overall, the highly sensitive and steadily piezoresistive responses demonstrate that the CNTs–CB/epoxy nanocomposites are attractive to be used as compressive strain sensors for structural health monitoring in civil infrastructures. [ABSTRACT FROM AUTHOR]

In this work, the electrical conductivity of nanocomposites filled with carbon black is simulated by the three-dimensional Monte Carlo method. First, three-dimensional model of the nanocomposites and carbon black is constructed and the conductive mechanism is studied. Then the calculation method of electrical conductivity of nanocomposites filled with carbon black is proposed according to the equivalent resistance of large-scale pure resistor network. Then the proposed electrical conductivity calculation method is verified by comparing with the simulation and experimental results. This result shows that it is feasible to directly obtain the conductivity of nanocomposites using the proposed conductivity calculation method. This study helps to estimate the electrical properties of nanocomposites filled with carbon black. And it also can help for studying nanocomposites filled with carbon nanotubes or graphene and the synergistic effect of hybrid fillers-filled nanocomposites. [ABSTRACT FROM AUTHOR]

As an energy storage device, Zn–air battery has great market prospects due to its relatively high theoretical energy density, low cost, safe and reliable performances. Since the cathodic oxygen reduction reaction (ORR) is a sluggish kinetic process, efficient electrocatalysts are essential to facilitate the ORR. Herein, we report the one-step synthesis of non-precious metals loaded C–N tubular nanocomposites via the pyrolysis of the mixture composed of dicyandiamide (DCD), Co/Ni acetates, ethylenediamine, and different organic carbon sources like soluble starch(st), β-cyclodextrin(cyc) and carbon black(cb). The prepared nanocomposites present a hollow tubular structure, and the Co/Ni nanoparticles are uniformly distributed on the CN nanotubes. In the prepared catalysts, Co3Ni2/CN(st) exhibits excellent ORR electroactivity close to the Pt/C catalyst in the alkaline medium. An alkaline Zn–air battery is assembled by using the Co3Ni2/CN(st) as the cathodic electrocatalyst. The open-circuit voltage reaches 1.51 V in 6 mol L−1 KOH electrolyte and the maximum power density reaches 331 mW cm−2. At different discharging current densities, the Co3Ni2/CN(st) battery exhibits stable and higher voltage plateaus than the Pt/C battery. The battery can discharge continuously for up to 80 and 51 h, corresponding to the constant discharge current density of 50 and 100 mA cm−2, respectively. The results show that the Co3Ni2/C–N(st) catalyst has potential application prospects as an excellent cathodic material for alkaline Zn–air batteries. CoNi loaded C–N tubular nanocomposites with well-defined hollow tubular structure, synthesized by one-step pyrolyzing the mixture of cobalt//nickel salts, dicyandiamide (DCD) and different carbon sources including soluble starch(st), β-cyclodextrin(cyc) and carbon black(cb), present superior performance as the cathodic catalysts of alkaline Zn–air batteries. [ABSTRACT FROM AUTHOR]

Metal-polymer Pt-Pd nanocomposites on a Nafion polymer membrane modified with carbon nanotubes and carbon black are synthesized by the chemical reduction of ions in aqueous organic solutions of reverse microemulsions. The functional characteristics of the nanocomposites are studied by cyclic voltammetry and atomic force microscopy. The synthesized nanocomposites exhibit strong catalytic activity in the formic acid oxidation reaction. It is found that, at the optimum ratio of platinum metals, the catalytic activity of the metal-polymer composites is higher than that of the carbon nanocomposites. [ABSTRACT FROM AUTHOR]

In this study, the behaviour of carbon nanotube/epoxy and carbon black/epoxy composites under dynamic load is studied via dynamic mechanical thermal analysis (DMTA) in combination with DC electrical resistivity measurements. DMTA measurements are carried out at fixed temperature whilst the dynamic loading frequency is varied. With this procedure, a loading frequency-dependence of the phase shift between DC electrical resistance and mechanical elongation (δ) is observed, although the force and elongation of the sample are still in phase. Moreover, the magnitude of this phase shift, as well as the amplitude of the DC electrical resistance change shows a clear dependence on the initial electrical conductivity of the samples. In addition, temperature sweeps are carried out to investigate the temperature dependency of the piezoresistance of the samples. An abrupt change in their sensitivity is observed as soon as the glass transition of the polymer is reached. However, the trend of the resistance change beyond the glass transition is substantially different between the nanocomposites containing carbon black and carbon nanotubes, revealing a strong influence of the network characteristics on the piezoresistive behaviour of these novel materials. [ABSTRACT FROM AUTHOR]