Thermal/electrical conductivity of polymers may not increase significantly with Carbon Nanotubes

Carbon nanotubes are unique nanostructures with remarkable electronic and mechanical properties. Structures based on carbon nanotubes offer an array of possibilities for nanometre-scale electronic applications. In a manner similar to carbon fibres used in composites to strengthen a structure or to enhance the electrical conductivity of the main constituent, carbon nanotubes could be combined with a host polymer to alter physical properties to specific applications. Superb conductors of heat and infinitesimal in size, carbon nanotubes might be used to prevent overheating in next-generation computing devices or as fillers to enhance thermal conductivity of insulating materials, such as durable plastics or engine oil. Since carbon nanotubes are very small, they could be used in polymer composites that could be formed into specific shapes, or in a low-viscosity composite that could be sprayed onto a surface as a conducting paint or coating.

Recently, a very interesting research conducted at Rensselaer Polytechnic Institute has revealed that carbon nanotubes may not act as a superconductor when mixed with polymers. This is in contradiction with what was originally envisaged when the nanotube was found to increase thermal conductivity by 2-3 times when incorporated at only very small level in the polymer matrix. It has been observed that carbon nanotubes, though superior thermal conductors by themselves, will not exhibit the same level of high conductivity when integrated into other materials.

Independent groups of scientists conducted computer simulations on model nanotube composites as well as some physical experiments and found the interfacial resistance between nanotube and other insulating material very high. This high resistance may limit the thermal conductivity of nanotubes. This possibly is the first evidence that what looked to be very promising regarding development of good conducting plastics material may not be as easy. Scientists now believe that both thermal and electrical conductivity of polymer will increase, but not very significantly.

However, an optimism exists about the use of carbon nanotubes to improve insulating materials. So although expectations have to be lowered, there is scope for nanotubes to improve materials for a number of other applications.

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