CNT

Carbon nanotubes

Carbon nanotubes have very special properties, among which is an
excellent electrical conductivity. Due to the high aspect ratio of the tubes
(the ratio of the length and the diameter of the tubes) small amounts
of nanotubes in a polymer matrix are able to form a conductive network.
Conductive composites with carbon nanotubes can be made with many
different matrix polymers, the material coin is based on PP.

Specific properties
Density: because of the small amount of filler this is almost equal to the
unfilled polymer.

Mechanical properties: depending on the added amount of tubes the
Young’s Modulus of these composites can be somewhat higher, and the
maximum strain lower. Due to the small amounts needed for a good
conductivity the influence on the properties can be much smaller than in
carbon black and stainless steel fiber filled compounds.

Electrical properties: depending on the amount and the dispersion of the
nanotubes the conductivity can range from sufficient for ESD applications
(1014-105 Ohm) to suitable for EMI shielding (105-1 Ohm). With high
bulk conductivities, conductive coatings are unnecessary.

Colour/surface
Colour always black. Surface is smoother than that of conductive materials
containing stainless steel fibers due to the smaller particles.

Processing
Depends on the matrix polymer: in general it is injection mouldable in a
similar way as the unfilled polymer, although the viscosity can be a bit
higher compared to the unfilled polymer.
However, it is very difficult to disperse nanotubes well in polymers.
Promolding is involved with the EU research project PolyCond
(polycond.eu), in which processing methods to improve the dispersion
of nanotubes and to optimise the properties are being investigated.

Applications
Electrically conductive nanocomposites with carbon nanotubes
can be applied in products that require protection from
electrostatic discharge (ESD) or electromagnetic interference (EMI).
It can be used instead of carbon black or stainless steel fiber filled
materials or it can replace conductive coatings in this type of
products.
– Electronics: housings of speakers, monitor, computers, etc.
– Medical: housings of sensitive medical equipment.
– Automotive and & aerospace industry: shielding of electronics,
electrostatic (powder)coating of plastic parts.
– Process- and food industry / offshore: many antistatic
applications in potentially explosive atmospheres (ATEX regulation)