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bioplasticsMAGAZINE_1405

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bioplasticsMAGAZINE_1405

Fibres & Textiles from

Fibres & Textiles from sugar cane, and Bio-PET used by CocaCola for their Plant Bottle, where only the 30 % ethylene glycol component is made from bio-ethanol. Although to our knowledge commercial fibre applications are not yet reported, the potential is obvious e.g. for commingled or co-woven fibre composites (PE) or traditional fibre applications for PET. Carbon fibre precursors No other material provides better material properties for lightweight constructions (automotive industry - especially electro cars, wind turbine fan blades, sporting goods etc.) than carbon fibres. By a slow heat treatment of an organic precursor fibre up to temperatures of 2500 °C (in some cases 3000 °C) a special arrangement of stacks of hexagonal carbon layers oriented along the fibre direction is formed. One of the first precursors were rayon fibres. However, low carbon yield (20 %), high carbonization temperatures and the need of high temperature stretch graphitization reduced their market share to less than 11 %. Nowadays, more than 85 % of the carbon fibres are based on polyacrylonitrile (PAN) from fossil feedstock. Thus, the price of the PAN directly depends on oil and gas prices. Several studies underline the enormous growth of the carbon fibre market which is expected to double within five years. To establish carbon fibres in the mass market, the current price of least 15 €/kg has to be significantly reduced. One possibility could be the use of lignin [6]. The existence of cyclic structures combined with a high carbon yield, which is comparable to PAN, offers the potential of lignin as a precursor material for carbon fibres. As a side product of the wood pulping process lignincontaining liquors are separated on a million tonnes scale per year. The challenge is to shape the extracted lignin into fibres of appropriate fineness as well as morphology (no voids) and provide mechanical properties, which at least allow the further continuous stabilization and carbonization. Brittleness is crucial point here. So far, reported properties of the ex-lignin carbon fibres are in the range of glass fibre values [6] yet with density advantages of 30 %. 10 €/kg for a mid-tech carbon fibre is considered by many OEMs as a break through value for mass applications in the automotive industry. With this or similar scenarios in mind, several alliances between research organizations, carbon fibre manufactures, automotive industry as well as pulp producers have been formed demonstrating the huge interest in developing a cost optimized lignin based carbon fibre filling the gap between glass and carbon fibres. Conclusions The use of biobased chemical fibres started over 100 years ago with viscose (rayon) and continues to grow in this field of regenerated cellulose (viscose, Tencel). Apart from cellulose, more and more biobased building blocks and thermoplastics, notably PLA, other polyesters (e.g. PTT) and polyamides enter the market which can be melt-spun into fibers with interesting properties. Even for high-tech products like carbon fibres, the use of biobased feedstock, here lignin, is C intensively pursued, yet on the research and development level. p M Y CM MY CY References CMY [1] Erdmann, J., Ganster, J., Fink, H.-P., PLA meets Rayon K – Tough PLA compounds reinforced with cellulose rayon for injection moulding. Bioplastics MAGAZINE [03/12] Vol 7, 22-25. [2] Northolt, M.G., Boerstoel, H., Maatman, H., Huisman, R., Veurink, J., Elzerman, H., The structure and properties of cellulose fibres spun from an anisotropic phosphoric acid solution. Polymer 42(2001), 8249-8264. [3] Fink, H.-P., Ebeling, H., Rihm, R., Fibre Formation from Liquid Crystalline Solutions of Cellulose Carbamate in N-Methylmorpholine-N-Oxide. Proceedings of the 7th Int. Symp. “Alternative Cellulose- Manufacturing, Forming, Properties”, 2006, Rudolstadt, p. 13-23 [4] Sixta, H., Progress in Regenerated Cellulose Fiber Production. Workshop on Cellulose Dissolution and regeneration, Göteborg, December 3rd, 2013 [5] Man-made Fiber Year Book 2013, Deutscher Fachverlag, October 2013, 4 [6] Fink, H.-P., Lehmann, A., Ganster, J., Bio-based carbon fibers – efforts and prospects. Technical Fibers International, Man-made Fiber Year Book 2013, Deutscher Fachverlag, October 2013, 44 www.iap.fraunhofer.de 26 bioplastics MAGAZINE [04/14] Vol. 9

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