3D printed Nanocellulosic materials and their composite By Vincent Li 1, 2 Advised by Professor H.Qi 1,3, and Professor Y. Deng 1, 2 1 Renewable Bioproducts Institute 2 School of Chemical and Biomolecular Engineering, 3 School of Mechanical Engineering Georgia Institute of Technology, Atlanta, GA, United State 5 th April, 2016 1
Motivation Petroleum based chemicals Unsustainable and Non-renewable Increasing effort for biomass production Agenda 2020: New source of sustainable materials to enable new paper products Need to fabricate high performance Smart paper with a process that is Reliable Facile Time efficient 2
3D Printing Advantages Novel and complicated structures can be constructed Additive and Green approach (saving raw materials) Agile manufacturing process Design and production are highly customizable Goal Utilize 3D printing for fabricating next generation bioproduct with complex functionalities 3
3D Printing Techniques Common 3D printing methods available Stereolithography Direct Ink Write 3D-Inkjet based Printing Fused Deposition Modeling Stereolithography Only area where light is illuminated is cured Then stage is lower to cure the next layer until 3D structure is formed Direct Ink Write Nozzle location is controlled to follow each layer pattern in designed 3D structure Ink deposition through the nozzle is controlled to form each layer until 3D structure is formed Stereolithography Direct Ink Write 4
Outline Cellulose Nanocrystals (CNC) Polymer composites via Stereolithographic (SLA) 3D Printing Demonstration of enhancement in composite s mechanical stiffness and strength Importance of CNC dispersibility and compatibility with base polymer matrix Nearly 100% Pure CNC structures via Direct Ink Write (DIW) 3D Printing Demonstration of high porosity CNC 3D structures Demonstration of various complex CNC 3D structures printed via DIW 5
Cellulose Nanocrystals CNC can be extracted from cell wall of trees and plants 1,2 Supplier: University of Maine (Manufactured at US FPL) Have high aspect ratios High strength and stiffness CNC-polymer composite materials 1,3 High elastic modulus (110-220 GPa) High tensile strength and low density 200 nm 1 Moon R. J. et al., Chem. Soc. Rev., 2011, 40, 3941-3994 2 Xu S. et al., Polymer., 2013, 54, 6589-6598 3 Gibson, L.J. et al.; J. R. Soc. Interface., 2012, 9, 2749-2766 200 nm 6
SLA Custom Built Printer Base Ink: PEGDA Mn 700 Biocompatible and Biodegradable Exposure time for each layer is 8 secs Solidworks Design PEGDA Mn 700 Octet-Strut Lattice 1.0 wt% FDCNC in PEGDA Mn 700 An Octet-Strut Unit Cell 7
Dogbone Structure from Modified Base Ink Formulation PEGDA 1 wt% FDCNC in PEGDA Modified Base Ink 0.2 wt% FDCNC 0.5 wt% FDCNC Modified Base Ink: 1 to 1 PEGDA_DiGlyDA Improve CNC dispersibility and compatibility via Hydrogen-bonding Glycerol 1, 3-diglycerolate diacrylate [DiGlyDA] Cellulose backbone chain and CNC 1.0 wt% FDCNC 2.0 wt% FDCNC 5.0 wt% FDCNC 8
Young s Modulus Analysis of FDCNC in Modified Base Ink 140 120 100 80 60 40 20 0 Modified Base Ink 0.2 wt% FDCNC 0.5 wt% FDCNC 1.0 wt% FDCNC 2.0 wt% FDCNC 5.0 wt% FDCNC Avg. Strain at break (%) 11.7 10.0 11.5 11.2 8.2 5.6 Avg. Ultimate Strength (MPa) 6.0 6.0 7.1 7.6 6.2 6.3 9
DMA Analysis of FDCNC Composite Mechanical Properties Both Glassy (-20 C) and Rubbery state (60 C) storage modulus increases as CNC loading increases Rubbery State storage modulus matches closely with Young s modulus measured at Room Temperature (25 C) 10
DMA Analysis of FDCNC Composite Glass Transition Temperature T g remain around 20 C as CNC loading increases Cross-linking density increases as CNC loading increases 11
Importance of Good FDCNC Dispersion from Halpin Tsai Model Fitted to minimize the sum of absolute residual error between experimental values and the Halpin Tsai model E f 111 GPa High CNC loading are likely not dispersed well in matrix Theoretical CNC Young s modulus with only low loading of FDCNC E f 5 GPa It is critical to have well dispersed CNC within polymer matrix 12
FDCNC Dispersion Characterization by Polarized Light Microscopy Exposure time: 100 ms 0 wt% FDCNC 0.2 wt% FDCNC 0.5 wt% FDCNC 100 µm 100 µm 100 µm 1.0 wt% FDCNC 2.0 wt% FDCNC 5.0 wt% FDCNC 100 µm 100 µm 100 µm 13
Outline Cellulose Nanocrystals (CNC) Polymer composites via Stereolithographic (SLA) 3D Printing Demonstration of enhancement in mechanical stiffness and strength Importance of CNC dispersibility and compatibility with base polymer matrix Nearly 100% Pure CNC structures via Direct Ink Write (DIW) 3D Printing Demonstration of high porosity CNC 3D structures Demonstration of various complex CNC 3D structures printed via DIW 14
DIW CNC Hydrogel 3D Printing Ultimus V Air Pressure Controller Custom built DIW Printer Fabricating ~100% pure CNC 3D structure without any polymer or cross-linker Air Compressor Stage y movement control Syringe with CNC x, z-movement control Potential application in patterned CNC scaffold for tissue engineering Biocompatible Biodegradable Limited Cytotoxicity Bottle Layer G-code Middle Layer G-code Image from Wake Forest Institute for Regenerative Medicine 15
DIW 3D Printer 11.8 wt% CNC in water Target structure: Honeycomb 20 wt% CNC in water 16
Porosity and SEM Analysis 20 wt% CNC in water Target structure: 1 cm 3 cube Resultant Porosity: 82 % 200 µm 10 µm 3D structure with high porosity can be successfully printed 2 µm 200 nm 17
1 cm 1 cm 1 cm 5 mm 18
Potential to include functionality to DIW Printed CNC Structures Can easily introduce colors to DIW 3D printed CNC structures Potentially replacing coloring with sizing agents or silver nanoparticle and fabricate CNC 3D structure with hydrophobicity or conductivity Multi-material DIW 3D printing 19
Conclusion and Future Work Conclusion Modified Base polymer is more compatible with CNC CNC compatibility and dispersibility was improved Young s modulus and ultimate strength of composite was enhanced Nearly pure CNC 3D structures with high porosity was printed Complex CNC 3D structures can be printed via DIW Future Work Functionalizing CNC DIW 3D Printing with CNF Increase DIW print resolution for final product with smoother surfaces Resolve structure cracking during freeze drying Multi-material DIW 3D printing Incorporate functionality into CNC structure Such as hydrophobicity or conductivity 20
Acknowledgment Funding provided by Georgia Tech Renewable Bioproducts Institute Professor H. Qi s research group Professor Y. Deng s research group Professor H. Qi Professor Y. Deng 21
Composite Thermal Stability Characterization through TGA Pure CNC T onset T max degradation Pure FDCNC 295 C 307 C Modified Base Ink 367 C 409 C 0.2 wt% FDCNC 370 C 409 C 0.5 wt% FDCNC 371 C 409 C 1.0 wt% FDCNC 373 C 411 C 2.0 wt% FDCNC 374 C 410 C 5.0 wt% FDCNC ~ 333 C 415 C Composite with increasing CNC content Adding CNC did not adversely affect thermal mechanical properties S1
First Derivative Curve from TGA S2