The value and exciting promises of natural fibres as raw materials for the manufacture of natural fibre-reinforced composites for different applications were again emphasised at a fibre-reinforced composites conference in Port Elizabeth.
In a paper delivered by Kozlowski Ryszard, Wladyka-Przybylak Maria and Bujnowicz Krzysztof from the Institute of Natural Fibres in Poland on the latest achievements in the area of composites reinforced with natural fibres, fibre plants were hailed as an answer for future manufacturing of natural fibre-reinforced composites.
These plants, including flax, hemp, ramie, kenaf, jute, abaca, sisal, coir and curaua are seen as promising lignocellulosic (a technical term for plants from which natural fibres are obtained).
The interest in natural fibre-reinforced polymer composite materials is rapidly growing in terms of industrial applications and basic research. The fibres are renewable, cheap, completely or partially recyclable and biodegradable. These fibres are incorporated into a matrix material, such as thermosetting plastics, thermoplastics or biopolymers and rubber.
From time immemorial, plants - such as flax, cotton, hemp, jute, sisal, kenaf, coir, pineapple, ramie, bamboo and banana - as well as wood were used as a source of lignocellulosic fibres. Today they are increasingly applied to the reinforcement of composites. Their availability, renewability, low density and price, as well as their satisfactory mechanical properties make them an attractive ecological alternative to glass, carbon and man-made fibres used for manufacturing of composites. The natural fibre-containing composites are more environmentally friendly and are used in transportation (automobiles, railway coaches, aerospace), military applications, building and construction industries (ceiling panelling, partition boards), packaging and consumer products.
Chemical and physical modifications of natural fibres are usually performed to correct for the deficiencies of these materials, especially to improve bonding and adhesion, dimensional stability and thermoplasticity. Surface modification of natural fibres can be used to optimise properties of the interface, changing hydrophobic and hydrophilic properties according to wishes.
Their great advantage is biodegradability and the fact that when combined with polymers or natural resins, they are as strong as steel, yet of lower density. Such composites may be used for vehicles, building elements, furniture, machine constructions, insulating materials, gardening and agriculture equipment, tropical housing and even grape holding structures.
In conventional lignocellulosic board composites a new bonding system based on enzymatic activation of lignin will play an advanced role in the future, replacing synthetic non-ecological resins.
Recycling of natural fibre-reinforced composites is relatively easy and convenient. This fact makes it one of the most important factors in forecasting the future growth of production and consumption of these materials.
The CSIR's natural fibres centre in Port Elizabeth, as one of the top four facilities of its kind in the world, is involved in developing a natural fibre-composite material in conjunction with several academic institutions and industry partners.
South Africa's resurgence in the global automotive market and the interest of leading players in the aerospace industries for sourcing natural fibre-reinforced composite products and technology from the country, also sparked a project on natural ribre-reinforced composites. This project under the AMTS programme is addressing the research problems and aims to fulfil the need for demanding technical applications in structural and exterior components.