Multiwall carbonnanotubes are rapidly emerging as an interesting alternate to carbon black forelectrostatic discharge applications.

"There willbe three important applications for multiwall carbon nanotubes," says PageMcAndrew, senior research scientist at Arkema, one of the leading developers ofthe new reinforcement technology. "One is imparting electrical conductivity,primarily for ESD applications. Two is for improving mechanical performance,and three is for flame retardancy."

Anyautomotive components that come in contact with fuel must have electrostaticdischarge properties. The Society of Automotive Engineers (SAE) recommends amaximum specific volume resistance of 106 ohm/cm for materials used for partswith fuel contact.

Carbonblack is typically used as a conductive filler so plastics can meet therequirement. However, loadings of 10 to 20 percent may be required, a levelthat could compromise some of the critical physical properties of the plastic, eitherpermeability or impact resistance.

"You canpreserve those properties if you use carbon nanotubes instead because you can getthe same ESD performance at loadings of just 1-2 percent," says McAndrew.

Costs of multiwallcarbon nanotubes; however, may be an issue, at least short-term. According toindustry sources, prices now are in the $50 to $70 per lb range, while conductivegrades of carbon black are sold in the range of $2 to $10 per lb. The loadingdifferential tilts the economics toward carbon nanotubes by a factor of 10.

If carbonblack works for a given application, there is little incentive to convert tocarbon nanotubes. Applications that benefit from the performance enhancementare expected to convert to multiwall carbon nanotubes, particularly as pricesdrop.

Productionfor multiwall carbon nanotubes is still in the pilot stage and global capacity todayis estimated by trade sources at less than 500 metric tons. Capacity could growtenfold or more based on announced increases in capacity.

Arkema, forinstance, inaugurated a 20-ton-per-year pilot plant in Lacq, Francein 2006 and is planning an increase to 550 metric tons based on announcements.