Man-made Cellulose Fibres as Reinforcement for Poly(lactic acid) (PLA) Composites

1. Man-made Cellulose Fibres as Reinforcement for Poly(lactic acid) (PLA) Composites International Congress Innovative Natural Fibre Composites for Industrial Applications April 15th-18th 2009 Nina Graupner & Jörg Müssig Hochschule Bremen / University of Applied Sciences Faculty 5 / BIOMIMETICS Biological Materials

2. Content Use of natural fibres for industrial applications Impact characteristics Production of composites Results Fibre characteristics Composite characteristics Influence of processing parameters Summary, conclusions & outlook

3. Bio-based materials for industrial applications (Gahle, 2008.-changed)

4. PLA/Kenaf – mobile phone + (Nviroplast) (NEC) (anonym, 2006)

5. Flax / PLA urn by Jakob Winter (Satzung, Germany) (Grashorn, 2007)

6. PLA/Kenaf spare tire cover made by Toyota • Spare tire cover in Toyota RAUM (2003) made from kenaf fibre reinforced PLA (based on sugar beet) • LCA on the spare tire cover showed reduced CO2 emissions volume by as much as 90 % compared to conventional petroleum-based plastics Index 100 Carbon neutral effect 50 0 Petroleum based plastics Bioplastics (Anonym, 2007 )

7. Problem: Impact Bast fibre reinforced composites mostly display high stiffness and tensile characteristics But: impact characteristics are often the limiting factors for a use as construction materials due to the force elongation characteristics of the bast fibres

8. Load-strain curves of different cellulose fibres Tensile strength, N/mm² Hemp Cotton Lyocell 800 700 600 500 Lyocell fibres combine high elongation and high tensile strength 400 300 200 100 1 2 3 4 5 6 7 8 9 10 Elongation, %

9. Impact strength of different composites

10. Lyocell as additive for impact improvement Unnotched Charpy impact strength Mixing 50 % hemp and 50 % Lyocell fibres increased the impact strength clearly (Graupner, 2009)

11. Production of Lyocell/PLA composites • Reinforcement: 3 kinds of Lyocell fibres (industrially gained fibres based on 100 % cellulose, density: 1.5 g/cm3) produced by Lenzing AG (Lenzing, Austria) in different fineness (15.0, 6.7, 1.3 dtex) • Matrix: Nature Works™ PLA polymer 6202D, density: 1.24 g/cm3, melting temperature 160-170°C, glass transition temperature: 60-65°C (Topkapi) (Packaging International)

12. Production of semi-finished parts • Production of multilayer webs and needle felts with fibre loads of 20 and 40 mass-% and a mass per unit area of 2000 g/m² Single layer web Fibres Positioned multilayer web Needle felt Carding machine Cross layer Needle felt machine (Müssig, 2001)

13. Compression moulding • Pre-cut parts of 300 x 250 mm2 were compression moulded (Rucks, Glauchau, Germany) • Pre-heating at 180°C for 10 min • Compression moulding with 3.2 MPa at 180°C for 10 min • Aluminium slats as spacer (thickness: 2 mm) • Demoulding at approx. 60°C

14. Results: Characteristics of 3 kinds of Lyocell fibres for composite production Clear influence of fibre fineness on mechanical fibre characteristics

15. Results: Tensile strength of composites made from multilayer webs vs. needle felts Influence of fibre fineness can be seen Composites made from the needle felts show significant higher tensile strength compared to composites made from the multilayer webs

16. Results: Reduction of fibre mass content of the multilayer webs Tensile strength Reduction of fibre mass content of the multilayer webs lead to increased tensile strength of the composites

17. Results: Impact strength of composites made from the multilayer webs Unnotched Charpy impact strength Increasing impact strength with raising fibre mass content Composites with a low degree of compaction No significant influences whether multilayer webs or needle felts were used

18. Results: SEM micrographs of tensile fractured surfaces 40 % Lyocell 1.3 multilayer web/PLA composite 40 % Lyocell 1.3 needle felt/PLA composite 20 % Lyocell 1.3 multilayer web/PLA composite

19. Results: Influence of process parameters of 40 % Lyocell multilayer web / PLA Tensile strength: 42 N/mm² Young´s modulus: 4142 N/mm² Impact strength: 33 kJ/m² Tensile strength: 82 N/mm² Young´s modulus: 6784 N/mm² Impact strength: 40 kJ/m² - 10 min pre-heating, 180 °C - 10 min compression moulding 180 °C - 10 min pre-heating, 180 °C - 10 min compression moulding 180 °C • 3 h pre-drying, 105 °C • - 20 min compression moulding 180 °C (Graupner, 2009) Clear inluence on: compaction Process parameters coating of fibres with matrix interfacial interactions between fibres and matrix

20. Summary, conclusions & outlook • Lyocell fibres have great potential as reinforcement (high tensile strength and high elongation at break) • Lyocell and PLA fibre are processable with conventional textile and formpressing techniques • Semi-finished textile products and process parameters have a clear influence on the composite characteristics • Compression moulding times and temperatures as well as the influence of pre-drying and pre-heating are important factors • Full potential of Lyocell fibres could not be achieved due to suboptimal process parameters using multilayer webs • Needle felts lead to better composite characteristics than multilayer webs • An optimised production leads to Lyocell/PLA composites which show high impact properties combined with good tensile characteristics

21. Thank you very much for your attention! Nina Graupner & Jörg Müssig University of Applied Sciences Faculty 5 / BIOMIMETICS Biological Materials email: nina.graupner@hs-bremen.de

22. Acknowledgements We thank … • Dr. Sames (Lenzing AG, Lenzing, Austria) for supplying Lyocell fibres • Dipl.-Ing. C. Grashorn (IST Ficotex, Bremen, Germany) for supplying PLA • Prof. Dr. A. S. Herrmann (Faserinstitut Bremen e.V., Bremen Germany) and G. Gödecke (NAFGO GmbH, Neerstedt, Germany) for support in semi-finished product and composite production • the students of the course Materials Research at University of Applied Sciences Bremen – Biomimetics for measuring tensile and impact strength of needle felt reinforced composites

23. References Anonym (2006): Complete mobile phone housing made of PLA. In: Bioplastics, Vol. 1, (06/01), p. 18 – 19 Anonym (2007): Bioplastics in Automotive Applications. Bioplastics Magazine, Vol. 2 (1), p. 14-18 Bax, B., Müssig, J. (2008): Impact and tensile properties of PLA/Cordenka and PLA/flax composites. Composites Science and Technology 2008; 68: 1601-1607 Gahle, C. (2008): Nova-Institut: Biowerkstoffe – Werkstoffe mit Zukunft: Aktuelle Marktdaten und attraktive Produktbeispiele. In: Biowerkstoff Report, Okt., Nov., Dez., p. 26 Grashorn, C. (2007): Erstes Serienprodukt aus naturfaserverstärktem PLA im Spritzguss. In: Nova Institut, Hürth, Germany; 5. N-FibreBase Kongress. Hürth 21st-22nd Mai 2007. –in German Graupner, N. (2008): Application of lignin as natural adhesion promoter in cotton fibre-reinforced poly(lactic acid) (PLA) composites. Journal of Materials Science 2008; 43 (15): 5222-5229 Graupner, N. (2009): Improvement of the Mechanical Properties of Biodegradable Hemp Fibre Reinforced Poly(lactic acid) (PLA) Composites by the Admixture of Man-made Cellulose Fibres. Journal of Composite Materials 2009; Vol. 43 (6): 689-702 Müssig, J. (2001): Untersuchung der Eignung heimischer Pflanzenfasern für die Herstellung von naturfaserverstärkten Duroplasten – vom Anbau zum Verbundwerkstoff -. Fortschritt-Berichte VDI Reihe 5 Nr. 630. Düsseldorf: VDI Verlag 2001, (ISBN 3-18-363005-2) Nviroplast:http://www.nviroplast.com/images/corn2resin.jpg&imgrefurl, 01.04.2009 NEC:http://i.treehugger.com/files/kenaf_phone.jpg&imgrefurl, 01.04.2009 Oksman, K., Skrifvars, M., Selin, J.-F. (2003): Natural fibres as reinforcement in polylactid acid (PLA) composites. Composites Science and Technology, 63: 1317-1324 Packaging International:http://www.packaging-int.com/images/companies/2017/veriplastimage2.jpg, 01.04.2009 Topkapi:http://www.topkapi-iplik.com.tr/images/prod_images/lyo3.jpg, 01.04.2009