Developed by Eeonyx, USA, it is claimed that conductive blends can be
produced in a number of polymer matrices with improved electrical and
mechanical properties. Melt flow and compounding are improved, with easier
end-product fabrication. For example, in some systems (such as ABS, nylons, and
polyesters) only half as much of the additive is needed to achieve the same
conductivity level as a typical carbon black loading.
The coated particles possess greater thermo-oxidative stability than ICPs
(300-3 50°C), so accommodating the majority of thermoplastics and thermosets
currently used in industry without degradation or loss of conductivity. The filler
has a greatly reduced surface area and pore volume compared with the original
carbon black. In a number of plastics matrices, conductive blends can be
produced with improved electrical, and mechanical properties.
11.7 Intrinsically Conductive Materials
Several companies have developed intrinsically conductive polymers. Notable is
a range of conductive dispersions based on ICPs such as polyaniline and
polypyrrole, developed by DSM and marketed under the name ConOuest.
The first commercial applications are emerging, and the company claims to have
overcome the problem of poor processability in common solvents by using a
dispersion of a conductive polymer and a waterborne binder resin. This uses
only a low percentage of the conductive polymer and, as the functional part is
located in the optimal position, the coating is more cost effective. The carrier
system - basically a polypyrrole shell and a polyurethane carrier resin - can be
modified by changing either component. A range of additives based on polymeric
or inorganic powders has also been developed which could be used as
alternatives to carbon black to achieve 'tuneable' conductivity or avoid
contamination. Mechanical properties are relatively good due to the low loading
required.
At very thin layers, the coating can be more transparent than is usually
observed with standard polypyrrole systems, because the high conductivity is
obtained with only a low amount of polypyrrole. There is a relatively high
absorption of infra-red radiation. At a layer thickness of 2 jim visible light
transmission is 90%, reflecting 35% of infra-red radiation. At higher layer
thickness, close to 100% reflection can be achieved. A possible application might
be for treatment of camouflage netting.
11. 8 Moulded Circuitry
Given that some basic technical problems can be overcome, metallic additives
have an exciting future with the possibility of moulding the complex electrical
and electronics circuits in electronics equipment, as are used now in
automobiles, rather than using printed circuitry. While printed circuits go a long
way, the next stage is to mould three-dimensional circuitry, and mixing metallic
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