Car manufacturers have been using natural fibres for decades. Now, researchers have shown that plantain, a starchy type of banana, is a promising source of composite materials for the automobile industry.
Some high-end sedans and coupes use natural fibres in composite materials for interior door panels, engine, interior and noise insulation, and internal engine covers. Unlike steels or aluminium, natural fibre composites do not rust or corrode. They can also be durable and easily molded.
The biggest benefits fibre reinforced polymer composites bring to cars are the light weight, good crash properties, and noise and vibration reducing characteristics.
But making more parts of a vehicle from renewable sources is a challenge. Natural fibre polymer composites can crack, break and bend. The reasons for this include too low tensile, flexural and impact strength in the composite material.
Researchers from the University of Johannesburg have now demonstrated that plantain, a starchy type of banana, is a promising source for an emerging type of composite materials for the automotive industry.
The natural plantain fibres are combined with carbon nanotubes and epoxy resin to form a natural fibre-reinforced polymer hybrid nanocomposite material.
The researchers moulded a composite material from epoxy resin, treated plantain fibers and carbon nanotubes. The optimum amount of nanotubes was 1% by weight of the plantain-epoxy resin combined. The resulting plantain nanocomposite was much stronger and stiffer than epoxy resin on its own.
The composite had 31% more tensile and 34% more flexural strength than the epoxy resin alone. The nanocomposite also had 52% higher tensile modulus and 29% higher flexural modulus than the epoxy resin alone.
“The hybridization of plantain with multi-walled carbon nanotubes increases the mechanical and thermal strength of the composite. These increases make the hybrid composite a competitive and alternative material for certain car parts,” said lead researcher Prof Tien-Chien Jen in a statement.
The researchers subjected the plantain nanocomposite to a series of standardised industrial tests. These included ASTM Test Methods D638 and D790; impact testing according to the ASTM A-370 standard; and ASTM D-2240. The tests showed that a composite with 1% nanotubes had the best strength and stiffness, compared to epoxy resin alone.