Q: Are most of these carbon nanocomposites?
A: Yes, most of them are either carbon nanotubes or carbon nanomaterials that are put in the matrix. Carbon is the choice for two reasons. One, carbon nanomaterials have very special multifunctional properties – including mechanical properties, electrical conductivity, thermal conductivity and barrier properties. The second reason is that carbon nanomaterial is probably one of the most commonly used nanomaterials in R&D, so there is more of it available than other types.
Q: Why are nanocomposites of interest to the composites industry?
A: In the early years of these applications, nanocomposites were used more for their mechanical properties. But later on [the automotive and aerospace industry] asked what else can you improve by using nanocomposites? They found out that if you put the nanomaterials into the composites – and if you design, arrange and manufacture them in specific ways – it can improve electric conductivity or thermal conductivity and maybe others like barrier properties, such as fire and smoke retardance.
If we put a thin layer of carbon nanomaterials close to the skin of a plastic or polymer composite structure, it significantly improves the fire retardancy. You’re talking about adding just a very thin layer, maybe 10 to 15 microns, even thinner than a piece of paper, and almost no weight. A 12 x 12-inch carbon nanotube sheet is less than one gram. So if you have an aircraft that has an accident, if the composite materials in the aircraft have this nanomaterial layer on the surfaces that will reduce the smoke and heat generation and also delay the fire. You can give passengers more time to escape.
Q: Are companies beginning to seriously look at nanocomposites?
A: We have been approached by probably more than a dozen companies in the last few years that are interested in different multifunctionalities of nanocomposites – electrical, thermal, barrier and mechanical. For example, one company was interested in putting carbon nanotubes into polymer composite structures for ships to improve their fire and smoke retardancy. Another company was looking at the possibility of replacing steel cables using lighter weight carbon nanotube-based nanocomposites for applications such as elevators.
Q: How does the industry classify nanocomposites?
A: There’s one general way for people to categorize them, by looking at their matrix materials. So you can have polymer nanocomposites, like the Toyota application. In their case the polymer or the matrix material was nylon, a thermoplastic. If you use the nanomaterial in a metal matrix, you have a metal matrix nanocomposite. There are other people working on the ceramic matrix nanocomposites; they put nanomaterials into a ceramic matrix to make ceramics with better properties.