Les futures fibres cellulosiques artificielles. Procédés écologiques pour générer des fibres de demain. Patrick Navard

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1 Les futures fibres cellulosiques artificielles. Procédés écologiques pour générer des fibres de demain Patrick Navard Centre de Mise en Forme des Matériaux (CEMEF) Ecole des Mines de Paris-CNRS France version 0.4 1

2 Differential Weight Fraction Biomass-based polymer activities in CEMEF Soluble fraction (4) SE DP 360 original wood pulp, SE DP 360 fraction 1, SE DP 360 fraction 2, SE DP 360 fraction 3, SE DP 360 fraction 4, Insoluble fractions (1, 2, 3) Basic and applied research 20 active projects with industry log Molar Mass Industrial Chair Bioplastiques Durable bioplastics EPNOE: European Polysaccharide Network of Excellence 2

3 Content A: Introduction: cellulose fibres B: Present fibres: properties and difficulties C: Fibres coming from new solvents D: Conclusions 3

4 A: Introduction: cellulose fibres B: Present fibres: properties and difficulties C: Fibres coming from new solvents D: Conclusions 4

5 Cellulose sources trees algae sea animals (tunicin) cotton fungi bacteria 5

6 Cellulose is the most abundant natural polymer on Earth. Cellulose cannot be melted. Cellulose must be either solubilized or derivetized. Cellulose is a «normal» polymer. 6

7 Organisation of a natural fiber - fiber diameter: microns - a very complex composite : cellulose, lignin, hemicellulose, proteins - the composition varies a lot! almost pure cellulose 50-95% cellulose 7

8 A: Introduction: cellulose fibres B: Present fibres: properties and difficulties C: Fibres coming from new solvents D: Conclusions 8

9 Mean fibre consumption per kg per person cellulosics Synthetics Cotton wool 30 Examples of fibres *Source: Lenzing AG constant increase (2 à 3% per year) cotton culture is not increasing sustainability issues 9

10 Why to use cellulose fibres? Confort in wet environment, softness This is due to the special properties of cellulose towards water: very hydrophylic, but not soluble Existence of many h-bonds around cellulose molecules water affinity Hydrophobic moieties water no dissolution in Swelling of fibers in water associated with an increase of mechanical resistance 10

11 0 s Swelling of a regenerated cellulose fibre 20-60s Swelling of cotton fibre 11

12 Two main choices Cotton Cultivated in fields Cotton hairs are nearly pure cellulose Viscose Based on cellulose extracted from wood or other plants Spun from a cellulose derivative solution 12

13 Cotton fibres World production : 25 million tonnes annually, accounting for 2.5% of the world's arable land. Pesticides: about 25% of pesticides used in the World. Water use: 2.6 per cent of the global water use. As a global average, 44 per cent of the water use for cotton growth and processing is not for serving the domestic market but for export. Consumers in the EU25 countries indirectly contribute for about 20 per cent to the desiccation of the Aral Sea. A.K. Chapagain et al, the water footprint of cotton consumption, Research Report Series No. 18, Unesco September

14 Viscose fibres World production : 14% of artificial fibres (clothes, tires). Invented by French scientist Hilaire de Chardonnet in Three British scientists, Charles Frederick Cross, Edward John Bevan, and Clayton Beadle patented the process in Preparation: pulp is dissolved in caustic soda and it is shredded and allowed to age. The aged pulp is then treated with carbon disulfide to form a yellowcolored cellulose xanthate, which is dissolved in caustic soda again. Spinning then regeneration (acid media or temperature). Cellulose cellulose xanthate cellulose Pollution: carbon disulfide and other by-products of the process. 14

15 Which solutions? Decrease environmental pressure of cotton growing «Coton bio» Decrease pollution of viscose process Possible but very costly Use other sources Bacterial cellulose?? Use other solvents Only one is industrialized (Lyocell process) Need to find other solvents 15

16 A: Introduction: cellulose fibres B: Present fibres: properties and difficulties C: Fibres coming from new solvents D: Conclusions 16

17 New solvents for processing cellulose fibres Three main possibilities Lyocell process (not really new) NaOH-water Ionic liquids 17

18 LYOCELL Process cellulose processing in N-methylmorpholine-N-oxide / water Solution preparation Pumping (up to 30bars) O C N H Filtering and spinning (through spinneret :40-400mm) Air gap treatment regeneration finishing 18

19 Dissolution, swelling and inactivity zones phase diagram NMMO H 2 O RAMIE FIBRES A: Dissolution A B C D B: Only irreversible swelling C: Only reversible swelling D: Inactivity From Chanzy et al, Journal of Applied Polymer Science,

20 Lyocell fibres: spun from a NMMO solution Comparison with viscose fibres in both dry and wet states : higher tensile strength higher modulus higher tear strength lower strain at break The textile properties in the wet state are very good. BUT: high tendency to fibrillation 20

21 warm humid air gap and precipitated in water 60,0 Normal atmosphere and precipitated in water 60,0 50,0 50,0 Percentage (%) 40,0 30,0 Percentage (%) 40,0 30,0 20,0 20,0 10,0 10,0 0,0 <50 nm [ nm] [ nm] [0.5-1 µm] [1-2 µm] >2 µm Ranges of fibril diameters 0,0 <50 nm [ nm] [ nm] [0.5-1 µm] [1-2 µm] >2 µm Ranges of fibril diameters cold dry air gap and precipitated in water 60,0 normal atmosphere and precipitated in NaOH 60,0 50,0 50,0 Percentage (%) 40,0 30,0 Percentage (%) 40,0 30,0 20,0 20,0 10,0 10,0 0,0 <50 nm [ nm] [ nm] [0.5-1 µm] [1-2 µm] >2 µm Ranges of fibril diameters 0,0 <50 nm [ nm] [ nm] [0.5-1 µm] [1-2 µm] >2 µm Ranges of fibril diameters 21

22 Under mechanical stress, in wet state, fibres fibrillate: fibrillation is linked to the strong orientation of cellulose chains. Source: Ducos et al., 2005 Dangerous process Environmentally safe (99.8% solvent recovery) 22

23 Net NREU (GJ/t fibre), Cradle-to-factory gate plus post-consumer waste incineration with energy recovery (recovery rate = 60% primary energy ) 100 Cradle-to-factory gate Net NREU Net NREU, lower range Net NREU, higher range Cotton: Cotton (US&CN) PET (W.Europe) -29 PP (W.Europe) PLA fibre, with wind PLA fibre, without wind Recovered energy from waste incineration (energy recovery rate 60%) Lenzing Viscose Asia Tencel, Austria Lenzing Modal Tencel, Austria, 2012 Lenzing Viscose Austria Li Shen and Martin 23 Patel Utrecht University

24 Net Global Warming Potential (t CO 2 eq./t fibre), Cradle-to-factory gate plus post-consumer waste incineration with energy recovery (recovery rate = 60% primary energy ) GHG emissions from waste incineration (energy recovery rate: 60%) Net GWP lower range Net GWP higher range Cradle-to-factory gate GWP (including carbon sequestration) Cotton: Cotton (US&CN) PET (W.Europe) PP (W.Europe) PLA fibre, without wind PLA fibre, with wind Lenzing Viscose Asia Tencel, Austria Tencel, Austria, Lenzing Modal Lenzing Viscose Austria 24

25 Single-score result NOGEPA weighting factors (normalised to world) 1 tonne fibre, cradle-to-factory gate, cotton =100 NOGEPA Single-score points (First normalised to World 1995) Cotton (US&CN) Lenzing Viscose Asia PET fibre (W.EU) PP fibre (W.EU) Tencel, Austria Lenzing Modal Global warming Abiotic depletion Ozone layer depletion Human toxicity Fresh water ecotoxicity Terrestrial ecotoxicity Photochemical oxidation Acidification Eutrophication Lenzing Viscose Austria Tencel, Austria 2012 Weighting factors (NOGEPA) Climate Change 32 Abiotic depletion* 8 Ozone layer depletion 5 Human toxicity 16 Fresh water ecotoxicity 6 Terrestrial ecotoxicity 5 Photochemical oxidation 8 Acidification 6 Eutrophication 13 Total 99 Source: Huppes et al (2003), except for abiotic depletion (marked with *), which is not excluded by Huppes et al. and is determined based on own estimation. 25

26 Na-OH Process Look simple: NaOH + water + cellulose at low temperatures (- 5 C) No pollution Invented during the 80 s by Japanese scientists Huge amount of research in Asia (mainly China now) and Europe But suffers major drawbacks 26

27 Bad, even very bad solvent Buckeye VFC swollen in 8 % NaOH water -5 C Borregaard VHF swollen in 8% NaOH water -5 C In 8% NaOH-water at -5 C under agitation, cellulose dissolves, but not very well, with many undissolved parts remaining. Solutions are gelling 27

28 Need to increase solubility and decrease gelation Un-treated solution Need complex pre-treatments of cellulose pulps Need adding additives like ZnO of urea 5% cellulose in 9%NaOH/water G', G'', Pa 10 G'', 25 C Not yet ready, if ever G'', 20 C G'', 25 C G', 20 C 0.01 t gel t gel time, min 28

29 Cellulose solvents: - Imidazolium-based Ionic Liquids:, room temperature liquid Dissolution: heating and stirring for several hours - NaOH-water Dissolution: [7% -10%] NaOH Intensive mixing for 2 hours at [-6 C - +1 C], melting point: ~60-70 C - Cellulose Microcrystalline cellulose = cellulose, DP 170 other native celluloses: DP 300, 500, 1000 bacterial cellulose, DP

30 Ionic liquids Ionic liquids (IL): new green cellulose solvents - non-toxic (is it sure?) and non-volatile - high termal stability - possible to dissolve high cellulose concentrations without pre-activation - can be tuned due to modifications in anions or cations - expensive, but possible to recycle 30

31 Ionic liquids Imidazolium-based Ionic Liquids:, room temperature liquid, melting point: ~60-70 C No commercial product yet 31

32 A: Introduction: cellulose fibres B: Present fibres: properties and difficulties C: Fibres coming from new solvents D: Conclusions 32

33 What is the future of cellulose fibres? It must be proved that they offer a REAL advantage over other fibres in terms of environment footprint. New, water-based solvents must be designed. Recent advances about hydrophobicity of cellulose offer reasons to hope that new solvents can be designed. 33

34 CEMEF