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Nina Graupner & Jörg Müssig / Lyocell/PLA Composites, April 16th, 2009

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


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Nina Graupner & Jörg Müssig / Lyocell/PLA Composites, 2009

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


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Bio-based materials for industrial applications

Biological materials, procedure & application

Amount (region)

Biodegradable plastics

(packaging industry)

60,000-70,000 t (Western Europe, 2007)

Biodegradable plastics

(permantent use)

30,000-40,000 t (Germany, 2007)

Compression moulding with natural fibres, without cotton

(automobile industry)

29,000 t (Germany, 2005)

Compression moulding with cotton fibres

(truck manufacturer)

79,000 t (Germany, 2003)

Natural fibre injection moulding and extrusion

3,000-4,000 t (Europe, 2006)

(Gahle, 2008.-changed)


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(anonym, 2006)

(NEC)

+

PLA/Kenaf – mobile phone

(Nviroplast)


5


Flax / PLA urn by Jakob Winter (Satzung, Germany)

(Grashorn, 2007)


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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

(Anonym, 2007 )

Carbon neutral effect

Index100

50

0Petroleum based plastics

Bioplastics


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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


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Load-strain curves of different cellulose fibres

Tensile strength, N/mm²

Elongation, %

200

100

300

400

500

600

700

800

1 2 3 4 5 6 7 8 9 10

Hemp

Cotton

Lyocell

Lyocell fibres combine high elongation and high tensile strength


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Impact strength of different composites

Kind of fibre Charpy impact strength of composites in kJ/m²

Charpy impact strength of neat PLA in kJ/m²

Reference

40 % hemp 10 24 (Graupner, 2009)

40 % flax 11 15 (Oksman et al., 2003)

40 % kenaf 9 24 (Graupner, 2008)

40 % cotton 29 24 (Graupner, 2008)

40 % Lyocell 40 24 (Graupner, 2008)

30 % Cordenka 70 16 (Bax & Müssig, 2008)


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Lyocell as additive for impact improvement

0

5

10

15

20

25

30

35

40

45

Pure PLA sample Hemp-PLA Lyocell-PLA Hemp/Lyocell/PLA

Cha

rpy

impa

ct s

tren

gth

in k

J/m

²

Mixing 50 % hemp and 50 % Lyocell fibres increased the impact strength clearly

Unnotched Charpy impact strength

(Graupner, 2009)


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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)

(Topkapi)

(Packaging International)

Matrix: Nature Works™ PLA polymer 6202D, density: 1.24 g/cm3, melting temperature 160-170°C, glass transition temperature: 60-65°C


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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

Fibres

Carding machine

Single layer web

Needle felt machine

Needle feltPositioned multilayer web

(Müssig, 2001)

Cross layer


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Compression moulding

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


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Results: Characteristics of 3 kinds of Lyocell fibres for composite production

Fibre width, µm

Tensile strength, N/mm²

Young´s modulus, N/mm²

Elongation at break, %

Lyocell 1.3 10.5 46.7 5260 15.3

Lyocell 6.7 23.3 30.9 3744 13.0

Lyocell 15.0 32.5 23.0 3013 11.9

Clear influence of fib

re fineness on mechanical fib

re characteristics


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Results: Tensile strength of composites made from multilayer webs vs. needle felts

Composites made from the needle felts show significant higher tensile strength compared to composites made from the multilayer webs

Influence of fibre fineness can be seen


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0

10

20

30

40

50

60

70

20% Lyocell 1.3 40% Lyocell 1.3 20% Lyocell 15.0 40% Lyocell 15.0

Ten

sile

str

eng

th i

n N

/mm

²

Multilayer webs, MD

Pure PLA sample

Results: Reduction of fibre mass content of the multilayer webs

Reduction of fibre mass content of the multilayer webs lead to increased tensile strength of the composites

Tensile strength


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0

5

10

15

20

25

30

35

40

45

20% Lyocell 1.3-PLA 40% Lyocell 1.3-PLA 20% Lyocell 15.0-PLA 40% Lyocell 15.0

Ch

arp

y im

pac

t st

ren

gth

in k

J/m

²

Multilayer webs, MD

Pure PLA sample

Results: Impact strength of composites made from the multilayer webs

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

Unnotched Charpy impact strength


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Results: SEM micrographs of tensile fractured surfaces

40 % Lyocell 1.3 needle felt/PLA composite

40 % Lyocell 1.3 multilayer web/PLA composite

20 % Lyocell 1.3 multilayer web/PLA composite


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Results: Influence of process parameters of 40 % Lyocell multilayer web / PLA

(Graupner, 2009)

Clear inluence on:

- 10 min pre-heating, 180 °C

- 10 min compression moulding 180 °C

- 3 h pre-drying, 105 °C


Process parameters compaction

coating of fibres with matrix

interfacial interactions between fibres and matrix

- 10 min pre-heating, 180 °C


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


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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


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Nina Graupner & Jörg Müssig

University of Applied Sciences

Faculty 5 / BIOMIMETICS

Biological Materials

email: [email protected]


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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


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ReferencesAnonym (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

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