"Fusion based additive processing of biopolymers" ltc.epfl.ch AMIG

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1 "Fusion based additive processing of biopolymers" ltc.epfl.ch

2 Outline Biopolymers Renewable polymers Biomedical grade polymers Processing Fusion of thermoplastic polymers Materials transformation phenomena Processing biopolymer composites Additive manufacturing Current R&D Applications 2

3 Biopolymers Renewable polymers From petroleum and from waste vegetables The Polylactide (PLA) family 3

4 Biomed polymers Biocompatible polymers Bioresorbable polymers Stryker Primary Knee Replacement System Medtronic Talent Abdominal Stent Graft RootReplica (Sunstar DS AG) Composite ortho and prostheis ICRC Limb prosthesis 4

5 Biomed polymers Sutures Fixation elements for maxillofacial surgery Dental membranes Biomaterials for bone augmentation Matrices for tissue engineering Bioresorbable screws (fixation) Vertebral cages Drug release Phusis 5

6 It s about scale Material structure at different scales Processing steps to control the structure and properties Scaling up to product 6

7 Macro-meso-micro Textiles Sofradim Covidien.com cm mm µm Yarns of fibres are placed and oriented to optimize local stiffness Non-wovens, wovens, knitted, embroidered textiles Angiogenesis, vascularization 7

8 Macro-meso-micro-nano Hydrogel Biocomposites cm mm µm nm Soft porous polymers containing liquids Photo-hydrogels reinforced by a network of cellulose microfibrils Stifness, swelling tailored by the level of molecules crosslinking 8 EPFL: LTC-LAPD-LBO

9 Macro-meso-micro Polymer Cellular Biocomposites cm mm µm Particles are processed into polymers for stiffness and osteoconductivity Yarns of fibres provide anisotropic composite foams Bone regeneration 9 EPFL: LTC-LBO

10 Macro-meso-micro Interfaces: Material-Living tissues cm mm µm 10 EPFL: LTC-LBO

11 Outline Biopolymers Renewable polymers Biomedical grade polymers Processing Fusion of thermoplastic polymers Materials transformation phenomena Processing biopolymer composites Additive manufacturing Current R&D Applications 11

12 AM of polymers Nozzle based processes Molten polymer Extrusion Fused Deposition Modelling, FDM Filament Deposition Liquids, binders 3D printing Light-based processes Stereolithography, SLA Mask-based or direct writing methods Selective laser sintering SLS Processes 12 Thermoplastic polymers ABS PC PA PEEK Polycaprolactones PCL Polylactides PLA, PGA, Copolymers, blends PEOT/PBT Photo-polymers Hydrogels, PEG, PEG-MA, PLA-PEG Modified PCL, polytrimethylcarbonate Limited choice of photo-polymerizable biomaterials Conductive polymers Polyacetylene Polypyrrole Polythiaphene Polyaniline Materials

13 Processing thermoplastic polymers Material transformation phenomena and window Processes and processing windows Voids Material temperature T m T g POLYMER MELTING Polymer, Fibres Preforms Impregnation Intimate contact Healing between granules, fibre yarns, plies CONSOLIDATION SOLIDIFICATION Final part 13 Heating time Cooling time Consolidation time Time

14 Fused Deposition Modelling Polymer fibres Polymer powder or granules Hybrid composite yarns multi-filament yarn reinforcing and functional fibres Feeding system Heating cartridge Polymer melting and flow Guiding and cooling nozzle Yarn impregnation Yarn consolidation Fusion bonding Intimate contact Polymer chain diffusion Crystallization 14

15 Consolidation : crystallization PA C/min 100 C/min Temperature [ C] C/min 2300 C/min cryst.=0% cryst.=20% cryst.=42% PA12/CF Time [s]

16 Consolidation : porosity content COMMINGLED YARN ( CY) thermoplastic powder reinforcing fibres thermoplastic fibers reinforcing fibres POWDER IMPREGNATED TOW (PIT) ( ) ( ) + + η 4 4 ln 2 ln 2 ) ( V o 2 f i i o i i i i i v c a R r r R R r r r r P P P K t 2 = V ) (1 V ) (1 = f 2 f 2 = 1 π + = 1 π k k r k b N n k t A k k r k b N n k v X = L l L l R R V V P t o f m ml fl a impregnation η + ml fl V V L l L l v X 1 1- = x y z d R f L l (t) t t o t 1 2l0 16

17 Processing thermoplastic polymers An example: Yarn placement exp. model 16 Void content [%] T=280 C T=180 C T=220 C Placement speed [mm/s] CY 17

18 Fusion bonding Polymer injection Temperature region of optimal bonding BONDING poor or no bonding t interdiffusion D 2 π =. V 4 τ degradation [ ( ) ] M M 2 X ( t) crystallization t 4 1 exp π = No( td ) 3 τ e d G( ξ ) dξ 3 ; t t d wetting resinflow Time intimate contact consolidation interdiffusion crystallization healing intimate contact t CI (T) = η(t) f 5P 0 + ω f a f f 0 + ω f

19 Fusion bonding : kinetics Degree of g b a Intimate contact Autohesion Bonding D s (τ) = τ c.i. dt i=1 τ au. dt D c.i. ( τ i τ i 1 ). D au. τ j,t j j=i+1 ( ) Time (s) Degree of progression for intimate contact, autohesion and thus bonding for polyamide 12 at 180 C under 2 MPa of contact pressure. 19 Non isothermal interfacial crystallization in PP

20 Processing biomed polymers Additional phenomena Degradation during processing Drying Molecular weigth drop Contamination Environment Tools Sterilization EtOH Gamma 20

21 Outline Biopolymers Renewable polymers Biomedical grade polymers Processing Fusion of thermoplastic polymers Materials transformation phenomena Processing biopolymer composites Additive manufacturing Current R&D Applications 21

22 Additive manufacturing : polymer solutions 3D printing based on nozzle-deposition system Polymer solutions (solvent!) 3mm/s, 5 bar 500µm between 70 µm struts Melba Navarro, 2013, IBEC Barcelona Get the right set of temperature/plastiziser/printing parameters Post-processing : shrinkage of struts during solvent evaporation!! Hydrogels : + in-situ crosslinking and swelling : final resolution! 22

23 Additive manufacturing : molten polymer + composites Polymers and composites : less shrinkage,+ higher viscosity, + higher mechanicalproperties + different degradation rates Bioextruders : deposition velocity (volume, nozzle diameter), with or without screw, pumping Each constituent material requires specific processing conditions Access to the design freedom of the composite, multi-material deposition Bulk and surface properties Thermoplastic scaffold and bioactive hydrogel P.Bartolo,

24 Applications Custom-made 3D structures Reproduce geometry of body parts, surgeon support, replica of in vivo milieu In vitro platforms to study cell response and drug screening scaffold pore size, geometry, wettability, adhesion, mechanical loading on cells behavior Templates/scaffolds for tissue regeneration Building inner architecture and surface properties Mechanical performance, permeability, nutrients diffusion,cell response 24

25 Conclusions 25

26 Building up from mm scale : mm Processing fibre composite today Tape and tow directional placements Towards thinner ply ( 2-3 fibre thickness) Towards 3D shape in cost-effective one-step process Spread Tow Tape placement Additive processing of laminate ( ply by ply) tow composite (placement and overinjection)

27 Building up from µm scale : µm Polymer fibres Polymer powder or granules Hybrid composite yarns multi-filament yarn reinforcing and functional fibres Feeding system Heating cartridge Polymer melting and flow Guiding and cooling nozzle Yarn impregnation Yarn consolidation Fusion bonding Intimate contact Polymer chain diffusion Crystallization 27 3D cellular biocomposites for implants, cells platforms and degradable devices

28 Building up from µm scale : µm 1. 3D deposition for main scaffold 2. Impregnation with bioactive hydrogel 3. Post processing (crosslinking, ) 1mm 28

29 LTC-LBO SNSF project Processing with single fibres not only at yarn level control fibre properties during processing of implant Processing 3D biocomposite be hybrid, anisotropic and bioactive Cartilage Bone 29 J.Izadifar et al, Funct. Biomater. 2012, mykneecartilage

30 FDM MicroAngela 30

31 AM: from Biomaterials to Regenerative Medicine Swiss Society of Biomaterials and Regenerative Medicine 20th Anniversary in 2015 Conference at EPFL, June 9th and 10th 2015 Biomaterials, Biofabrication, Tissue Engineering 31

32 London museum of science 32

33 Merci EPFL-LTC EPFL-LBO, EPFL-LAPD CHUV SNSF, CTI, FP7 Eric Boillat YOU 33