Flexibility conductive fibres

A fibre may be defined as a structure that is fine, flexible and exhibits a high length-to-width ratio. A conductive fibre can be defined as an electrically conductive element having the structure of a fibre. Thus, a metal nail and thick copper wire are electrically conductive but not fibres, as they are neither fine nor flexible. In contrast, for the present purposes, a fine copper wire and silver-coated polymer fibre can both be categorized as conductive fibres. 

Many other opportunities exist due to the enormous flexibility of the preparative method, and the ability to incorporate many different species. Very recently, a great deal of work has been published concerning methods of producing these materials with specific physical forms, such as spheres, discs and fibres. Such possibilities will pave the way to new application areas such as molecular wires, where the silica fibre acts as an insulator, and the inside of the pore is filled with a metal or indeed a conducting polymer, such that nanoscale wires and electronic devices can be fabricated. Initial work on the production of highly porous electrodes has already been successfully carried out, and the extension to uni-directional bundles of wires will no doubt soon follow. 

The results are plotted in Figure 15-8. To get a low thermal conductivity we would like to have a low fibre Iraction, but if we choose it too low, the mat is so flexible that it can stand no stresses. The value = 0.04 is probably a compromise. 

Polypyrrole/quartz fibre composite samples [344] and mechanically strong and flexible Kevlar/polypyr-role hybrid fibers with room temperature conductivities of 10 S cm [345,346] have also been obtained. 

Polyaniline grafted onto flexible surfaces can find applications as a new material for the control of EMI/ESD. These materials are free from corrosion and may prove to be better than metal fibre/powder-filled composites, which are susceptible to galvanic corrosion or loss of conductivity due to friction, as in graphite-reinforced fibre composites which are brittle. 

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