Fabrication of all-cellulose composites from end-of-life textiles and ionic liquids

Transcription

1 Fabrication of all-cellulose composites from end-of-life textiles and ionic liquids Mikael Skrifvars 1, Behnaz Baghaei 1, Sam Compiet 1 and Hom Dhakal 2 1) Faculty of Textiles, Engineering and Business, University of Borås, Sweden 2) Advanced Polymer and Composites (APC) Research Group, School of Engineering, University of Portsmouth, Portsmouth, U.K. Presentation at the 29 th Annual International SICOMP Conference, Luleå, Sweden, May 28-29, 2018

2 Global textile fiber market Source: 2

3 /publications/a-new-textiles-economyredesigning-fashions-future 3

4 Research question: 4

5 Research project: Recycling of end-of-life textile materials by fabrication of all-cellulose composite Financial support from Formas - a Swedish Research Council for Sustainable Development Formas grant FR-2016/0005, 3M SEK

6 All-cellulose composites (ACCs) - Both matrix and reinforcement are based on cellulose - Prepared by controlled dissolution and solidification of cellulose - The cellulose fibres acting as reinforcement should stay partly intact during process Cellulose fibre and matrix Processing routes: a) 1-step: Addition of a cellulose solvent to a cellulose reinforcement b) 2-step: Combination of a pre-dissolved cellulose solution and a cellulose reinforcement 6

7 Thermoplastic all-polymer composites Curv - polypropylene tapes/fibres in polypropylene matrix Benefits compared to conventional composites - Improved interfacial compatibility as matrix and reinforcement are chemically identical - Easier recycling, as one material component - Very good mechanical properties and performance compared to other PP composites - Allows new component designs due to processing route 7

8 Cellulose materials for preparation of all-cellulose composites - Cellulose micro/nanofibers - Cellulose nanowhiskers - Microcrystalline cellulose - Bacterial cellulose - Pulp and paper - Long cellulose fibres/filaments - Non-woven cellulose fabrics - Woven fabrics Dissolution of cellulose polymer difficult due to intra- and intermolecular hydrogen bonds and crystallinity For structural composites it is a benefit to use cellulose in the form of organized fabrics with anisotropic properties End-of-life cotton/viscose textiles are a potential candidate for allcellulose composites 8

9 Cellulose solvents for non-derivatized cellulose Dissolves the cellulose by intermolecular interactions between solvent and cellulose - Ionic liquids: high dissolution capacity, low vapour pressure, easy recovery, thermal stability - LiCl/dimethyl acetamide: requires activation in polar medium and long dissolution times - NaOH/urea/thiourea: requires process temperature 10 to + 4 C - N-methyl morpholine oxide (NMMO): used in Lyocell process Challenges: Cost and availability, toxicity and safety, process requirements, recyclability 10

10 Experimental procedure - overview 1. Preparation of dissolved cellulose the resin 2. Impregnation of end-of-life denim fabrics the reinforcement 3. Solvent infusion processing by vacuum prepreg formation 4. Solvent removal and cellulose regeneration prepreg formation 5. Consolidation by compression moulding the composite 6. Testing and evaluation 11

11 Materials Reinforcement: - Post-consumer denim fabric (Texaid, Switzerland) Cotton twill fabric, 420 g/m2 Resin: - Lyocell staple fibres (Lenzing AG, Austria) - Cotton/polyester (50:50) discharged bed linen fabrics (Textilia, Sweden) Ionic liquid: 1-butyl-3-methylimiodazolium acetate (BMIMAc) Ethanol, Sulphuric acid 12

12 Separation of cotton from cotton/polyester fabrics % recovery rate 10 N H 2 SO 4 Cellulose powder Process according to Cellulose 17 (2010) 215 Polyester fabric 13

13 Resin - cellulose dissolving in ionic liquid 6 wt-% separated cotton powder or Lyocell staple fibres 200 ml BMIMAc, mixed with mechanical stirred at 120 C, for 2 h, 600 rpm The optimal cellulose concentration was evaluated to get optimal viscosity for further processing Three different cellulose/il solutions were used as resins: Lyocell cellulose with fresh IL Separated cotton with fresh IL Lyocell cellulose with recycled IL 14

14 Solvent infusion processing of laminates 20x20 cm 2 denim fabrics, pre-dried at 80 C for 24 h 4 denim layers, 0 /90 lay up direction Pre-impregnation with cellulose/il solution Covered with vacuum bag, and laminate compaction by vacuum Removal of vacuum bag Heating 95 C, 1.5 h Cellulose regeneration in water bath (300 ml), h Washing 1:1 water:etanol 16 h Consolidation in hot press at 120 C and 3.3 MPa, 8 h 15

15 Ionic liquid solvent recycling Water:etanol solution with IL was distilled in a rotary evaporator at 55 C and 20 mbar vacuum IL purity was verified by IR spectroscopy Water still present in recovered IL, reuse requires proper drying 16

16 Testing and characterisation Tensile testing according to ISO 527 Flexural testing according to ISO KT Tinius Olsen 10 mm/min and 1 kn loading Impact testing ISO 179 Zwick pendulum test instrument, 5 J Un-notched and edge-wise Nano-indentation tests 16 symmetrical indentations, 0.1 mn initial load, 15 mn maximum load, 5 s dwell time, 2 mn/s strain rate Scanning electron microscopy EVO MA10, Zeiss field emission SEM, samples were sputtered with gold layer Micro-CT Zeiss Xradia 520 Versa system, 70kV, 6W 17

17 Laminate morphology - SEM Laminate D1 Lyocell cellulose with fresh IL Laminate D3 Lyocell cellulose with recycled IL 18

18 Micro-computed tomography Laminate D1 Lyocell cellulose with fresh IL 19

19 Fractured laminate morphology - SEM Laminate D2 Separated cotton with fresh IL 60 X magnification Fractured by 3-point bending Laminate D2 Separated cotton with fresh IL 150 X magnification 20

20 Mechanical characteristics Sample Tensile strength (MPa) E- modulus (GPa) Flexural strength (MPa) Flexural modulus (GPa) Charpy impact strength (kj/m2) Hardness (GPa) D (2.34) 3.46 (0.89) (5.59) 2.00 (0.58) (8.12) 1.57 D (0.48) 4.30 (0.67) (2.95) 2.74 (0.32) (8.96) 1.70 D (1.34) 2.48 (0.38) (11.13) 1.79 (0.29) (6.03) 1.15 D1 = Lyocell cellulose with fresh IL D2 = Separated cotton with fresh IL D3 = Lyocell cellulose with recycled IL 21

21 Spörl et al. Macromol. Mater. Eng. 303 (2018) Cordenka viscose yarn, UD fabric, 0 /90 lay up Obtained values: TS = MPa, EM = GPa FS = MPa, FM = GPa, IS = kj/m 2 22

22 Dormanns et al. Composites A 85 (2016) 65 Cordenka viscose yarn, 2/2 twill weave, UD fabric layup, 450 g/m 2 Obtained values: TS = MPa, EM = GPa 23

23 Conclusions 1. Production of ACC composites from ionic liquid and end-of-life textiles was demonstrated 2. A lab production process for ACCs has been set up, and the process conditions have been investigated 3. The obtained composites have mechanical properties comparable with in the literature reported data for similar type ACCs 4. Upon loading, the laminates fracture along the fabric fabric interface, which indicates insufficient bonding under used process conditions Further work 1. Optimisation of process conditions regarding impregnation and consolidation time to avoid delamination 2. Evaluate pretreatments of end-of-life textiles (mechanical and chemical) 3. Evaluate effect of water/humidity exposure on composite properties 4. Tailor process for manufacturing more complicated composites 25

24 Thank you for your attention! Questions: 26