Natural Fibre Composites: Automotive Applications
The search for materials with better properties, and more stringent environmental legislation, are pushing the automakers to constantly look for products that are lighter, more eco-friendly, and are still adequate for mass production at low cost. This pursuit is leading to the increase in use of composite materials in automotive components. Composite materials from petroleum-based resins and fibres, like carbon, Kevlar or glass, can well deliver the required mechanical and production requirements, but they pose considerable problems, mainly in terms of their end-of-life process. Vegetable fibres, like jute, ramie, coconut, sisal, flax or hemp, are renewable and biodegradable resources with a production requiring little energy, and provide carbon sequestration. Therefore, they present less environmental impact. They also lead to lighter components than those that use others fibres, like fibre glass. However, some shortcomings are present. Vegetable fibres have high moisture absorption, low microbial resistance, low processing temperature and quality variations, depending on growth conditions or processing.
The incorporation of vegetable fibres in automotive components, mostly for interior parts, is nowadays a reality. The tendency is to increase their use. Components like door panels, seat backs, headliners or dashboards, with fibres from coconut, flax, sisal or hemp, are incorporated by the major car suppliers. DaimlerChrysler is one of the biggest proponents, using up to 50 components with vegetable fibres in its European vehicles.
For “completely green” composites, a bio-based resin also is needed. They come from renewable resources like plant oil, polysaccharides (cellulose and starch) or proteins. Their incorporation in automotive components has already started, but some issues regarding performance and high cost need to be addressed.
Undoubtedly, vegetable fibre-reinforced composite materials are effectively applied in automotive components, with increasing frequency and environmental awareness. This increased awareness is also leading to the successful replacement of petroleum-based resins by bio-based ones.