Conductive compositions

As already noted, the main merit of fibers used as a filler for conducting composite materials is that only low threshold concentrations are necessary to reach the desired level of composite conductivity. However, introduction of fiber fillers into a polymer with the help of ordinary plastic materials processing equipment presents certain difficulties which are bound up mainly with significant shearing deformations entailing fiber destruction and, thereby, a decrease of parameter 1/d which determines the value of the percolation threshold. 

NEW CONCEPT FOR THE METAL-AIR BATTERIES USING COMPOSITES CONDUCTING POLYMERS / EXPANDED GRAPHITE AS CATALYSTS... 

V.G. Khomenko, V.Z. Barsukov, A.S. Katashinskii and T.I. Motronyuk. New concept for the metal-air batteries using composites conducting polymers/ expanded graphite. This book. 

Y. Y. Huang, J. E. Marshall, C. Gonzalez-Lopez, E. M. Terentjev, Variation in carbon nanotube polymer composite conductivity from the effects of processing, Dispersion, Aging and Sample Size, Mater. Express, vol. 1, pp. 315-328, 2011. 

H. Tsuji, Y. Kawashima, H. Takikawa, S. Tanaka, Poly(L-lactide)/nano-structured carbon composites Conductivity, thermal properties, crystallization, and biodegradation., Polymer, vol. 48, pp. 4213-4225, 2007. 

Where a is the composite conductivity, a0 a proportionally coefficient, Vfc the percolation threshold and t an exponent that depends on the dimensionality of the system. For high aspect ratio nanofillers the percolation threshold is several orders of magnitude lower than for traditional fillers such as carbon black, and is in fact often lower than predictions using statistical percolation theory, this anomaly being usually attributed to flocculation [24] (Fig. 8.3). 

Thus, the perpendicular conductivity is always less than the parallel conductivity. If the second component is a number of spheres embedded in a matrix of the first component, then the composite conductivity is given by the Maxwell equation when the volume fraction of spheres is very small ... 

Studies of the solution properties of heteropoly acids have been somewhat spares despite the general interest in these compounds for many years. Deterents to such studies have been primarily the instability of the compounds and the uncertainty concerning their composition. Conductivity and pH measurements on the heteropoly acids H4[PMonVO40] and H5[PMoi0V2O40] in aqueous solutions and mixed solvents has already been discussed. The acids are strong 1-4 and 1-5 electrolytes, respectively. Activity coefficients of ammonium 6-heteropolymolybdates have been reported and shown these to be 1 3 electrolytes197. ... 

Fig. 8.16 Variation of static and cyclic fatigue crack velocity, daldt, with the applied (maximum) stress intensity factor, KIy for fatigue tests on A CVSiCw composites conducted at 1400°C. The inset shows a schematic of the change in crack velocity for a change from static- cyclic-> static loading at fixed Kt.51...

To cite a practical example, 20% by mass of 12/mi diameter glass fibre coated with silver (70 nm thick) mixed in a thermosetting polyester resin gave a composite conductivity of 2.5 x 104fi-lm 1. From Equation (8.37) the calculated value is 5.3 x 104fl-lm-1, which compares reasonably well with the experiment, if one takes into account that some disintegration of the fibre is inevitable in the mixing process. 

Material (Composition) Conductivity (S/cm) Measurement Temperature (°C) Synthesis Method Ref. 

S. Haufe, D. Prochnow, D. Schneider, O. Geier, D. Freude, and U. Slimming. Polyphosphate composite Conductivity and NMR studies. Solid State Ionics 176, 955-963 2005. 

Entry Weight No. of MMT (g) Weight of Oxidant (g) Volume ofANI (ml) Time of polymerization (h) % yield ofPANI % PANI per g of composite Conductivity (S/cm)... 

Formation of a stable nanoelectrospray is dependent on many variables including the fluid surface tension, solvent composition, conductivity of the fluid and the applied voltage and pressure. Flow rate flowing through a nozzle is dependent on these variables as well as the inner diameter of the nozzle. As an example, a nozzle with a 5.5 pm inner diameter and 28 pm outer diameter will spray a solution of 50% methanol with 0.1% acetic acid at a flow rate of lOOnLmin 1 with an applied voltage of 1.4kV and pressure and 0.2 psi. A nozzle with a 2.5 pm inner diameter and 28 pm outer diameter will spray this same solution at a flow rate of 20nLmin 1 with an applied voltage of 1.2 kV and pressure of 0.3 psi. 

Polypyrrole PVDF-TFE a = 5 to 50 S/cm for composites. Conductive, mechanically ductile Niwaeffl/., 1987... 

Figure 2. Thermal hysteresis loop of the opal-V02 composite conductivity [7].

Ram M. K., Yavuz O., Lahsangah V., and Aldissi M., CO gas sensing from ultrathin nano-composite conducting polymer film,, Sens. Actuators B, 106(2), 750-757, 2005. 

At very small concentration of Cu (XcJ around 1 vol. %, the R value of the composite film is close to that of pure PPX. In this case, Cu nanoparticles fully isolated in matrix do not interact with one another and do not influence the composite conductivity. But is seen in the table, the increase of Xq, even to 3.5 vol. % leads to the sharp fall of / as a result of charge transfer between Cu nanoparticles. The probability of such transfer rises exponentially with the decrease of distance between particles— that is, with Xq, increasing. 

Figure 14.6 Sensing ofHCI and NH3 using PPy/carbon nanofiber composites (a) SEM image of the nanofiber mat and (b) TEM of a single composite nanofibers (c) responses of the composite nanocables (a and b) and bulk PPy (c and d) to NHj (a and c) and HC (b and d) (Reprinted with permission from Sensors and Actuators B Chemical, CO gas sensing from ultrathin nano-composite conducting polymer film byM. K. Ram, O. Yavuz, f. Lahsangah and M. Aldissi, 106, 2, 750-757. Copyright (2005) Elsevier Ltd)...

---