Electrically conductive composite material based on silicon carbide

The article presents the results of the study aimed at establishing the main process parameters of the preparation of an electrically conductive composite material containing silicon carbide, graphite, aluminous cement and sodium silicate. This composite material can be used as a heating element in heat accumulators for the operating temperature range of 600–10000C. The effects of the amount of sodium silicate within the range of 12–18 wt.% and the compacting pressure within the range of 40-70 N / mm2 on the changes in the properties of the samples after drying were investigated. It was established that the mechanical strength of the samples of 34.2 N mm–2 and 33.4 N mm–2 can be achieved at the compacting pressure of 60 N mm–2 and 50 N mm–2 and the sodium silicate content of 14 wt.% and 16 wt.%, respectively. It was shown that a porous microstructure of the composite is formed in the course of samples annealing at the temperatures of 600–10000C due to physicochemical processes of transformations of sodium silicate and its interaction with aluminous cement; this porous microstructure is characterized by open porosity in the range of 23.14–25.11% and mechanical strength in the range of 33.2–32.0 N mm–2. The fabricated composite material after its annealing at 10000C shows a low electrical resistivity of 0.06710–2–0.01410–2 Ohmm at the electric current of 28–94 A and the voltage of 19.2–13.2 V.

Electrically Conductive Composite based on Functionalized Carbon Nanotubes/Epoxy Resin

This work is devoted to the study of the effect of carbon nanotubes functionalization on the electrical conductivity of composite materials based on them. Carbon nanotubes were functionalized by treatment in nitric acid and isopropyl alcohol. Changes in the morphology of multi-walled carbon nanotubes during liquid-phase functionalization were investigated using Auger-electron microscopy. Samples of composite material on the basis of initial and functionalized carbon nanotubes and epoxy resin were prepared and the concentration dependence of electrical conductivity using the four-probe method was studied. The study reveals the effect of functionalization in various solutions on the electrophysical properties of the obtained carbon nanotubes/epoxy composites.

Single and binary protein electroultrafiltration using poly(vinyl-alcohol)-carbon nanotube (PVA-CNT) composite membranes

Electrically conductive composite ultrafiltration membranes composed of carbon nanotubes have exhibited efficient fouling inhibition in wastewater treatment applications. In the current study, poly(vinyl-alcohol)-carbon nanotube membranes were applied to fed batch crossflow electroultrafiltration of dilute (0.1 g/L of each species) single and binary protein solutions of α-lactalbumin and hen egg-white lysozyme at pH 7.4, 4 mM ionic strength, and 1 psi. Electroultrafiltration using the poly(vinyl-alcohol)-carbon nanotube composite membranes yielded temporary enhancements in sieving for single protein filtration and in selectivity for binary protein separation compared to ultrafiltration using the unmodified PS-35 membranes. Assessment of membrane fouling based on permeate flux, zeta potential measurements, and scanning electron microscopy visualization of the conditioned membranes indicated significant resulting protein adsorption and aggregation which limited the duration of improvement during electroultrafiltration with an applied cathodic potential of −4.6 V (vs. Ag/AgCl). These results imply that appropriate optimization of electroultrafiltration using carbon nanotube-deposited polymeric membranes may provide substantial short-term improvements in binary protein separations.

Direct grafting-from of PEDOT from a photoreactive Zr-based MOF – a novel route to electrically conductive composite materials

Photochemical modification of Zr-bzpdc-MOF with PEDOT through direct polymerization of EDOT at the MOF surface gives an electrically conductive material.