Conductive composites carbon black

Carbon Blacks. The high electrical conductivity of carbon black is utili2ed where its color is not objectionable and its reinforcing action is used (see Fillers Composites). Carbon black increases the electrical conductance of the polymer to which it is added, and therefore its effectiveness does not depend on moisture absorption (see Carbon, carbon black). 

Preparation of Electro-Conductive Polyimide-Carbon Black Composites... 

The salt monomer method was successfully applied to the preparation of the electrically-conducting polyimide-carbon black composites [62]. The composites are prepared as follows An aqueous solution of salt monomer 9PMA was mixed with carbon black, giving a suspension. This was evaporated to dryness under reduced pressure to afford a homogeneously-mixed powder composed of the salt monomer and carbon black. The powder was subjected to solid-state thermal polycondensation in the form of a pellet at 240 °C for 1 h under atmospheric pressure. The semiconducting aliphatic polyimides (P-9PM, Tm=315 °C) having electric conductivity of about 10"6 S/cm was readily obtained by mixing only 1 wt% of carbon black based on the polyimide. 

If the estimated fitting parameters are compared to the predicted values of percolation theory, one finds that all three exponents are much larger than expected. The value of the conductivity exponent ji=7A is in line with the data obtained in Sect. 3.3.2, confirming the non-universal percolation behavior of the conductivity of carbon black filled rubber composites. However, the values of the critical exponents q=m= 10.1 also seem to be influenced by the same mechanism, i.e., the superimposed kinetic aggregation process considered above (Eq. 16). This is not surprising, since both characteristic time scales of the system depend on the diffusion of the charge carriers characterized by the conductivity. 

Conductive powder composites Carbon-black composites... 

Fig. 8.19 Temperature dependence of the conductivity of carbon-black/ epoxy composites at different carbon-black loadings. Reprinted from El-Tantawy et al. (2002). Copyright 2002, with permission from Elsevier.

The conductivity of carbon black/polymer composites is a function of a number of parameters, including ... 

There are two kinds of carbon-based fillers used to produce antistatic and conducting PP composites carbon black and carbon fiber. 

Xu X B, Li Z M, Yang M B, Jiang S and Huang R (2005) The role of the surface microstructure of the microfibrils in an electrically conductive microfibrillar carbon black/poly(ethylene terephthal-ate)/polyethylene composite, Carbon 43 1479-1487. 

Pourabas and Peyghambardoost [70] prepared positive temperature coefficient composites by using metal-modified and unmodified carbon black in a matrix of high-density polyethylene. Modification with metallic particles led to properties that were related to changing the surface properties of the carbon black. The intrinsic electrical conduction of carbon black also changed after modification. These changes in properties endowed some desirable characteristics to the positive temperature coefficients. 

Thermally Stable Intrinsically Conductive Polymer-Carbon Black Composites as New Additives for Plastics... 

Figure 27 The calculated and experimental dielectric constant (top) and conductivity (bottom) vs. particle volume fraction for carbon black/PVC composite at 915 MIIz. The parameter used for calculation is that the dielectric constant and conductivity of carbon black and PVC is 0, 10 S/cm, 3, 5xl0 S/cm, respectively. Experimental data were obtained at room temperature. Reproduced with permission from G. Banhegyi, Colloid Polym. Sci., 266(1988)11.

In many composites, conducting fillers (carbon black, carbon nanotubes, or metal nanoparticles) are added to make material conductive. The relationship between composite morphology and electrical conductivity has been studied extensively, especially in the context of carbon black filled polymers [156-162]. It is well known that the dependence of conductivity on the loading of conductive filler, percolation theory there is some threshold filler loading below which there is no conductive pathway through the system and conductivity is zero above the threshold, conductivity grows very rapidly as ... 

A number of processes have been used to produce carbon black including the oil-furnace, impingement (channel), lampblack, and the thermal decomposition of natural gas and acetjiene (3). These processes produce different grades of carbon and are referred to by the process by which they are made, eg, oil-furnace black, lampblack, thermal black, acetylene black, and channel-type impingement black. A small amount of by-product carbon from the manufacture of synthesis gas from Hquid hydrocarbons has found appHcations in electrically conductive compositions. The different grades from the various processes have certain unique characteristics, but it is now possible to produce reasonable approximations of most of these grades by the od-fumace process. Since over 95% of the total output of carbon black is produced by the od-fumace process, this article emphasizes this process. 

Composite structures that consist of carbon particles and a polymer or plastic material are useful for bipolar separators or electrode substrates in aqueous batteries. These structures must be impermeable to the electrolyte and electrochemical reactants or products. Furthermore, they must have acceptable electronic conductivity and mechanical properties. The physicochemical properties of carbon blacks, which are commonly used, have a major effect on the desirable properties of the conductive composite structures. Physicochemical properties such as the surface... 

For the second method the threshold concentration of the filler in a composite material amounts to about 5 volume %, i.e. below the percolation threshold for statistical mixtures. It is bound up with the fact that carbon black particles are capable (in terms of energy) of being used to form conducting chain structures, because of the availability of functional groups on their surfaces. This relatively sparing method of composite material manufacture like film moulding by solvent evaporation facilitates the forming of chain structures. 

Natural graphite and synthetic graphite were used as fillers for the manufacture of conducting composite materials by the polymerization filling technique [24, 53-56], The manufacture of conducting polymer composite materials by this technique on the basis of some kinds of carbon black is also known [51, 52],... 

Any review devoted to conducting composites would be incomplete if the application fields of such composites were not described even if briefly. One of the first, if not the foremost, examples of the utilization of the CPCM is antistatic materials [1], For the materials of this kind resistivity q of less than 106 to 108 Ohm cm is not required, and this is achieved by introducing small amounts (several per cent) of a conducting filler, say, carbon black [4],... 

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