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All - Cellulose Hierarchical Composites: Using Bacterial Cellulose To Modify Sisal Fibres

All - Cellulose Hierarchical Composites: Using Bacterial Cellulose To Modify Sisal Fibres. A. Abbott , J. Juntaro & A. Bismarck. Polymer & Composite Engineering (PaCE) Group Department of Chemical Engineering. Outline. Need for renewable materials Composite philosophy

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All - Cellulose Hierarchical Composites: Using Bacterial Cellulose To Modify Sisal Fibres

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  1. All-Cellulose Hierarchical Composites: Using Bacterial Cellulose To Modify Sisal Fibres A. Abbott, J. Juntaro & A. Bismarck Polymer & Composite Engineering (PaCE) Group Department of Chemical Engineering

  2. Outline • Need for renewable materials • Composite philosophy • Innovative modification of natural fibres • Cellulose matrix processing • Route towards green composites • Truly green hierarchical composites • Possible applications

  3. Driving Forces To Green... • Growing environmental awareness • Stringent EOL legislation in the EU • Limitation of landfill capacity • Landfills count over 40% of plastic wastes • Endangering of wild life • Most plastics are not Biodegradable !

  4. Legislation & Materials • EU agreed on a sustainable politic • End-of-life Vehicle directive 2000/53/EC • Legislation to encourage re-use, recycling and other forms of recovery of ELVs • Landfill directive 1999/31/EC • Legislation to prevent or reduce negative effects on the environment from land filling of waste • WEEE directive 2002/96/EC • Legislation to tackle rapidly increasing waste stream of EEE by recycling of EEE and limitation of wastes.

  5. The Green Future • Strong need for new and reliable materials • Requirements: • Be recyclable, re-usable and biodegradable • Obtained from sustainable resources • Yield properties comparable to common plastics • Be produced at low cost • Be resistant to weathering A possible solution would be the use of cellulose based composite materials!

  6. Composite Architecture (1) • Composite have at least 2 constituents • Fillers • Different purposes: reinforcement, fire-retardant, colour, cost reduction, additives, etc... • Different sizes: from mesoscale to nanoscale • Polymer matrix • Aim: transfer load to fillers, hold and protect fillers • Type: thermosets, thermoplastics • Interface • Impact on composite properties

  7. Polymeric matrix Composite Architecture (2) Natural fibre Interface • Cross-section of randomly reinforced biodegradable composite

  8. Composite Philosophy

  9. Hierarchical Composites N-N Dimethylacetamide (DMAc), Lithium Chloride (LiCl), Sodium hydroxide (NaOH) Bacterial cellulose (BC)

  10. Green Fibre Modification (1) • Gluconobacter fermentation for 1 week • Strain BRP 2001(suitable for dynamic culture) • Modification during cellulose production Bioflow culture conditions: temp 37°C ; pH 5.5 ; agitation 700 rpm ; aeration 5 l/min ; carbon source fructose

  11. Green Fibre Modification (2)

  12. Green Fibre Modification (3) Fibre extraction from organic mass in 0.1 M NaOH 80°C 20 min

  13. Modification & Fibre Properties • No significant mechanical properties loss after grafting procedure Fibre conditioned @ 20°C and 50% RH; test performed @ 1mm/min, gauge length 20mm

  14. Modification & Fibre Crystallinity • Overall crystallinity increase after BC grafting • Surface fibre modified by green grafting process Crystallinity evaluated with Segal’s equation

  15. Cellulose Matrix Processing • Matrix system obtained from MCC • Properties tailoring f(processing time) • Brittle to ductile type behaviour • Short fibres incorporation after suitable dissolution time Dissolution mechanism presented by MacCormick (1979) N-N Dimethylacetamide (DMAc), Lithium Chloride (LiCl)

  16. Matrix Crystallinity vs. Processing

  17. Matrix Toughness vs. Processing

  18. All-Cellulose Composites Prop.(1) Testing Standards ISO 527-2 @ 1mm/min

  19. All-Cellulose Composites Prop.(2) Testing Standards ISO 527-2 @ 1mm/min

  20. All-Cellulose Composites Prop.(3) Test configuration: single cantilever beam Heating rate 5OC/min @ 1Hz in nitrogen atmosphere

  21. SEM All-Cellulose Composite SEM micrograph post cryo-fracture

  22. SEM Hierarchical Composite SEM micrograph post cryo-fracture

  23. SEM Hierarchical Composite SEM micrograph post cryo-fracture

  24. Conclusion • Effective fibre surface modification with BC • Grafted fibre bulk properties unchanged • Improved interfacial adhesion & stress transfer • 100% cellulose composite • Hierarchical composite structure • Principle transferable to other systems • Fibre functionalization by cellulose chemistry

  25. Potential Applications Adapted from book: Natural fibers, Biopolymer and Biocomposites; Mohanty (2006)

  26. Acknowledgements • Dr Sakis Mantalaris (Head of Biological Systems Engineering Laboratory)

  27. Thanks For Listening! Any Questions ?

  28. Matrix & Thermal Degradation Heating rate 5oC/min under nitrogen atmosphere

  29. Bacterial Synthesised Products(1) • Reinforcement: Bacterial Cellulose (BC) • Highly crystalline, pure cellulose compound • Tayloring BC properties during fermentation Czaja, et. al, Biomaterials 2006

  30. Bacterial Synthesised Products(2) • BC produced by Gluconobacter and others • Ribbon-shape fibrils 8-50 nm diameter • Chemically identical to plant cellulose Jonas & farah 1998

  31. BC Production (2) BC network & Bacteria Young’s modulus of single nanofibril: 78 GPa (similar to glass fibres) (Guhasos et al.,2005) 89% Crystallinity (Czaja et al.,2004)

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