Fibre-reinforced composites – glass fibre, carbon fibre, natural fibres and the Biotex Product
Traditional glass fibre and carbon fibre filled composites are ubiquitous – finding application in road and rail transport, aerospace and structural applications. In contrast, natural fibre composites are less well established. Natural fibres offer advantages over traditional reinforcing fibres including; low cost, low density, high toughness, acceptable specific strength properties, ease of separation, enhanced energy recovery, carbon dioxide sequestration and biodegradability. The incorporation of natural fibres into a biopolymer matrix produces a biocomposite. Biocomposites offer significant environmental gains, reduced energy consumption, lighter weight, insulation and sound absorption properties. They can also overcome the health hazards associated with VOCs and glass fibre.
This project has adopted and improved, a commercially available biocomposite material (Biotex) in which woven mats of well-aligned flax fibres are incorporated in a Polylactic Acid (PLA). The innovative aspect of the Biotex product is the twistless yarns with long, well-aligned, flax fibres. The parallel arrangement of the flax fibres was specifically developed to derive maximum reinforcement. Strands of spun fibres have considerable off-axis fibre alignment, which detracts in terms of improved strength. Whereas, in injection moulded or press moulded parts the natural fibres are generally short and randomly oriented giving relatively low mechanical properties. The twistless technology used in the Biotex product provides the high levels of performance and processibility normally associated with glass reinforced composite materials.
This project has adopted and improved, a commercially available biocomposite material (Biotex) in which woven mats of well-aligned flax fibres are incorporated in a Polylactic Acid (PLA). The innovative aspect of the Biotex product is the twistless yarns with long, well-aligned, flax fibres. The parallel arrangement of the flax fibres was specifically developed to derive maximum reinforcement. Strands of spun fibres have considerable off-axis fibre alignment, which detracts in terms of improved strength. Whereas, in injection moulded or press moulded parts the natural fibres are generally short and randomly oriented giving relatively low mechanical properties. The twistless technology used in the Biotex product provides the high levels of performance and processibility normally associated with glass reinforced composite materials.
Biotex weaving
Examples of Biotex fabric
The natural, flax fibres used in the Biotex product are renewable and have a low environmental impact during processing. The fibres are commingled with polymer strands which melt, flow and coat the flax fibres; bundles of which are easy to impregnate. When PLA is used to form the polymer matrix the result is a 100% renewable material that can be recycled or composted at the end of its life
Biotex material processing
The Biotex product is supplied in the form of flexible, woven mats that can be shaped using hot compression moulding at 180-200 °C and 10-100 psi. The required number of woven mats are laid in the mould and then pressed or stamped in order to form the shaped product.