Scientists in Brazil have used fibres from pineapples and bananas to create a new generation of super-strong automotive plastics.
They believe the plant material may in future not only be used to build car bodies, but also engine parts.
Manufacturers are already testing the plastics and could be using them in cars within two years, say the researchers.
Dr Alcides Leao, from Sao Paulo State University, said reinforcing plastic with microscopic fibres from delicate fruits such as pineapples and bananas made them super-strong.
“The properties of these plastics are incredible,” he told the 241st meeting of the American Chemical Society in Anaheim, California.
“They are light, but very strong – 30 per cent lighter and three to four times stronger (than regular plastic). We believe that a lot of car parts, including dashboards, bumpers, side panels, will be made of nano-sized fruit fibres in the future. For one thing, they will help reduce the weight of cars, and that will improve fuel economy.”
Some of the fibres were almost as stiff as Kevlar, the super-strong material used to make bullet-proof vests and lightweight armour, he said.
The fibre-reinforced plastics were also more impervious to heat, spilled petrol, water and oxygen than ordinary automotive plastics.
Plant fibres from wood have been used for centuries to make paper. But recently scientists have discovered that intensive processing of wood releases ultra-small “nano” cellulose fibres so small that 50,000 could fit across the width of a single human hair.
These ultra-thin fibres can be used to strengthen other materials in the same way that glass fibre is produced by embedding fine strands of glass in plastic.
Dr Leao has been working with unusual plant fibres to make plastics that are stronger, lighter and more eco-friendly than those now in use.
Among the most promising raw materials were pineapple leaves and stems, and curaua, a plant related to the pineapple that is cultivated in South America. Other good sources of nano-cellulose were bananas, coir fibres found in coconut shells, sisal fibres from the agave plant, and fique, another plant related to pineapples.
Although the process is costly, it takes just one pound of nano-cellulose to produce 100 pounds of super-strong, lightweight plastic, said the scientists.
“So far we're focusing on replacing automotive plastic. But in the future we may be able to replace steel and aluminium automotive parts using these plant-based nano-cellulose materials,” Dr Leao said.
The plastics also had potential in medical applications such as artificial heart valves, ligaments and hip joints, he said.