By using fibers from seemingly delicate fruits such as bananas and pineapples，the scientists say they can strengthen new plastics，making them not only stronger and lighter，but more lasting as well.“They are light，but very strong－30 percent lighter and three to four times stronger，”research leader Alcides Leao from Brazil said.Some of the fibers can be as strong as Kevlar，the super－strong material used to make bullet－proof vests.Besides，the plastics are also more resistant to damage from heat，water，oxygen and even overflowed gasoline.

　　Cellulose(纤维素)is the main component of wood and has been used for centuries to make paper.Recently scientists have discovered that intensive processing of wood releases tiny or“nano”cellulose fibers，so tiny that 50，000 could fit across the width of a single human hair.When mixed with other raw materials，these nano－cellulose fibers can make plastic stronger.

　　According to Leao，pineapple leaves and stems，and a plant related to the pineapple in South America，called curaua，rather than wood may be the most proper source for nano－cellulose.To create the plastics，researchers put the leaves and stems of pineapples and other plants into a device similar to a pressure cooker.Then they added certain chemicals and heated the mixture over several cycles，producing a powder that was then added to the plastics.

　　The process is costly，but it takes just one pound of nano－cellulose to produce 100 pounds of super－strong，lightweight plastic，Leao pointed out.Some carmakers have already tested these nano－cellulose plastics and scientists have predicted the plastics would be in use within two years，mainly for car bodies.

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