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“Green” cars
could be made from pineapples and bananas
ANAHEIM, March 27,
2011 — Your next new car hopefully won’t be a lemon. But it could be a
pineapple or a banana. That’s because scientists in Brazil have developed a
more effective way to use fibers 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. They described the work, which could
lead to stronger, lighter, and more sustainable materials for cars and other
products, here today at the 241st National Meeting & Exposition
of the American Chemical Society (ACS).
|
Automotive
plastics of the future could be made out of nano-sized fibers produced from
pineapples, bananas, and other fruits. Credit:
iStock. |
Study leader
Alcides Leão, Ph.D., 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,” Leão said, “They are
light, but very strong — 30 per cent 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.”
Besides weight
reduction, nano-cellulose reinforced plastics have mechanical advantages over
conventional automotive plastics, Leão 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.
Cellulose is the
main material that makes up the wood in trees and other parts of plants. Its
ordinary-size fibers have been used for centuries to make paper, extracted from
wood that is ground up and processed. In more recent years, scientists have
discovered that intensive processing of wood releases ultra-small, or “nano”
cellulose fibers, so tiny that 50,000 could fit inside across the width of a
single strand of human hair. Like fibers made from glass, carbon, and other
materials, nano-cellulose fibers can be
added to raw material used to make plastics, producing reinforced
plastics that are stronger and more durable.
Leão said that
pineapple leaves and stems, rather than wood, may be the most promising source
for nano-cellulose. He is with Sao Paulo State University in Sao Paulo, Brazil.
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 process is costly, but it takes
just one pound of nano-cellulose to produce 100 pounds of super-strong,
lightweight plastic, the scientists said.
“So far, we’re
focusing on replacing automotive plastics,” said Leão. “But in the future, we
may be able to replace steel and aluminum automotive parts using these
plant-based nanocellulose materials.”
Similar plastics
also show promise for future use in medical applications, such as replacement
materials for artificial heart valves, artificial ligaments, and hip joints,
Leão and colleagues said.
The scientists
acknowledge funding from the government of Brazil, Pematec, Toro
Industria and Comercio Ltd.,
and other private companies.
The American
Chemical Society is a non-profit organization chartered by the U.S. Congress.
With more than 163,000 members, ACS is the world’s largest scientific society
and a global leader in providing access to chemistry-related research through
its multiple databases, peer-reviewed journals and scientific conferences. Its
main offices are in Washington, D.C., and Columbus, Ohio.
# # #
CONTACT:
Alcides Leão, Ph.D.
São Paulo State
University
College of Agricultural Sciences
São Paulo,
Brazil
Phone: 011-55-14-3811-7257
Fax: 011-55-14-3811-7100
Email: alcidesleao@fca.unesp.br
ABSTRACT:
Cellulose nanocrystals, also known as cellulose whiskers, are the crystalline domains of cellulosic sources. These nanoparticles, when isolated, have been evaluated as reinforcement material in polymeric matrixes due to their potential to improve, among others, the mechanical, optical, and dielectric properties of these matrixes. This work has been to study the production and incorporation of nanocellulose from several sources (pineapple, curaua, banana, coir) into thermoplastics matrix composites. The aim of the incorporation of nanocellulose as reinforcement is to reduce the weight of the parts as well as improvement in its mechanical properties, with the consequent advantages. The methodology from the fibers extraction, nanocellulose and composites production are described. A comparison between the traditional natural fibers reinforcement agents at macro, micro scales are compared. The nanocellulose showed and important alternative for composites production for automotive applications.