Soon, 'green' cars made from pineapples, bananas

Wondering what your next new car will be made of? Possibly from pineapples or bananas.

Brazilian scientists have developed a more effective way to use fibres from these and other plants in a new generation of automotive plastics that are stronger, lighter, and more eco-friendly than plastics now in use.

Study leader Alcides Leao said the fibers used to reinforce the new plastics may come from delicate fruits like bananas and pineapples, but they are super strong.

Some of these so-called nano-cellulose fibers are almost as stiff as Kevlar, the renowned super-strong material used in armor and bulletproof vests. Unlike Kevlar and other traditional plastics, which are made from petroleum or natural gas, nano-cellulose fibers are completely renewable.

"The properties of these plastics are incredible. They are light, but very strong - 30% lighter and 3-to-4 times stronger. We believe that a lot of car parts, including dashboards, bumpers, side panels, will be made of nano-sized fruit fibers in the future. For one thing, they will help reduce the weight of cars and that will improve fuel economy," said Leao.

Besides weight reduction, nano-cellulose reinforced plastics have mechanical advantages over conventional automotive plastics, Leao added. These include greater resistance to damage from heat, spilled gasoline, water, and oxygen.

With automobile manufacturers already testing nano-cellulose-reinforced plastics, with promising results, he predicted they would be used within two years.

Leao said that pineapple leaves and stems, rather than wood, might be the most promising source for nano-cellulose.

Another is curaua, a plant related to pineapple that is cultivated in South America. Other good sources include bananas; coir fibers found in coconut shells; typha, or "cattails;" sisal fibers produced from the agave plant; and fique, another plant related to pineapples.

To prepare the nano-fibers, the scientists insert the leaves and stems of pineapples or other plants into a device similar to a pressure cooker. They then add certain chemicals to the plants and heat the mixture over several cycles, producing a fine material that resembles talcum powder.

The scientists said though the process is costly, it takes just one pound of nano-cellulose to produce 100 pounds of super-strong, lightweight plastic.
 
"So far, we're focusing on replacing automotive plastics. But in the future, we may be able to replace steel and aluminum automotive parts using these plant-based nanocellulose materials," said Leao.

The work has been described at the 241st National Meeting and Exposition of the American Chemical Society (ACS).