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

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

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 20°C and 50% RH; test 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 1mm/min

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

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

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)

Thanks For Listening! Any Questions ?

29 Matrix & Thermal Degradation Heating rate 5 o C/min under nitrogen atmosphere

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

31 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

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