Chemical modification and printability of shear-thinning hydrogel inks for direct-write 3D printing

Polymer ◽  
2018 ◽  
Vol 152 ◽  
pp. 42-50 ◽  
Author(s):  
Patrick T. Smith ◽  
Amrita Basu ◽  
Abhijit Saha ◽  
Alshakim Nelson
Keyword(s):  
3D Printing ◽  
Chemical Modification ◽  
Shear Thinning ◽  
Direct Write

Direct-print photopolymerization for 3D printing

2017 ◽  
Vol 23 (2) ◽  
pp. 337-343 ◽  
Author(s):  
Morteza Vatani ◽  
Jae-Won Choi
Keyword(s):  
3D Printing ◽  
Shear Thinning ◽  
Direct Write ◽  
Content Type ◽  
3D Structures ◽  
Standard Guideline ◽  
Original Contribution ◽  
Printing System ◽  
Shape Retention

Purpose This work aims to present a guideline for ink development used in extrusion-based direct-write (DW) (also referred to as direct-print [DP]) technique and combine the extrusion with instant photopolymerization to present a solvent-free DP photopolymerization (DPP) method to fill the gap between 3D printing and printing multi-functional 3D structures. Design/methodology/approach A DP process called DPP was developed by integration of a screw-driven micro-dispenser into XYZ translation stages. The process was equipped with direct photopolymerization to facilitate the creation of 3D structures. The required characteristics of inks used in this technique were simulated through dispersion of fumed silica particles into photocurable resins to transform them into viscoelastic inks. The characterization method of these inks and the required level of shear thinning and thixotropic properties is presented. Findings Shear thinning and thixotropic properties are necessary components of the inks used in DPP process and other DP techniques. These properties are desirable to facilitate printing and filament shape retention. Extrusion of viscoelastic inks out of a nozzle generates a filament capable of retaining its geometry. Likewise, instant photopolymerization of the dispensed filaments prevents deformation due to the weight of filaments or accumulated weight of layers. Originality/value The DPP process with material-reforming methods has been shown, where there remain many shortcomings in realizing a DP-based 3D printing process with instant photopolymerization in existing literature, as well as a standard guideline and material requirements. The suggested method can be extended to develop a new commercial 3D printing system and printable inks to create various functional 3D structures including sensors, actuators and electronics, where nanoparticles are involved for their functionalities. Particularly, an original contribution to the determination of a rheological property of an ink is provided.

3D printing of spent coffee ground derived biochar reinforced epoxy composites

2021 ◽  
pp. 002199832110022
Author(s):  
Ahmed Alhelal ◽  
Zaheeruddin Mohammed ◽  
Shaik Jeelani ◽  
Vijaya K Rangari
Keyword(s):  
3D Printing ◽  
Flexural Modulus ◽  
Flexural Properties ◽  
Direct Write ◽  
Thermal And Mechanical Properties ◽  
Spent Coffee Grounds ◽  
Coffee Grounds ◽  
Spent Coffee Ground ◽  
Coffee Ground ◽  
3D Printed

Semi-crystalline carbon biochar is derived from spent coffee grounds (SCG) by a controlled pyrolysis process at high temperature/pressure conditions. Obtained biochar is characterized using XRD, SEM, and TEM techniques. Biochar particles are in the micrometer range with nanostructured morphologies. The SCG biochar thus produced is used as reinforcement in epoxy resin to 3 D print samples using the direct-write (DW) method with 1 and 3 wt. % loadings. Rheology results show that the addition of biochar makes resin viscous, enabling it to be stable soon after print; however, it could also lead to clogging of resin in printer head. The printed samples are characterized for chemical, thermal and mechanical properties using FTIR, TGA, DMA and flexure tests. Storage modulus improved with 1 wt. % biochar addition up to 27.5% and flexural modulus and strength increased up to 55.55% and 43.30% respectively. However, with higher loading of 3 wt. % both viscoelastic and flexural properties of 3D printed samples drastically reduced thus undermining the feasibility of 3D printing biochar reinforced epoxies at higher loadings.

scholarly journals Progress in Starch-Based Materials for Food Packaging Applications

2022 ◽  
Vol 3 (1) ◽  
pp. 136-177
Author(s):  
Lucia García-Guzmán ◽  
Gustavo Cabrera-Barjas ◽  
Cintya G. Soria-Hernández ◽  
Johanna Castaño ◽  
Andrea Y. Guadarrama-Lezama ◽  
...  
Keyword(s):  
3D Printing ◽  
Chemical Modification ◽  
Shelf Life ◽  
Food Packaging ◽  
Environmentally Friendly ◽  
High Demand ◽  
Promising Alternative ◽  
Recent Developments ◽  
Single Use ◽  
Processing Techniques

The food packaging sector generates large volumes of plastic waste due to the high demand for packaged products with a short shelf-life. Biopolymers such as starch-based materials are a promising alternative to non-renewable resins, offering a sustainable and environmentally friendly food packaging alternative for single-use products. This article provides a chronology of the development of starch-based materials for food packaging. Particular emphasis is placed on the challenges faced in processing these materials using conventional processing techniques for thermoplastics and other emerging techniques such as electrospinning and 3D printing. The improvement of the performance of starch-based materials by blending with other biopolymers, use of micro- and nano-sized reinforcements, and chemical modification of starch is discussed. Finally, an overview of recent developments of these materials in smart food packaging is given.

scholarly journals Printable Alginate Hydrogels with Embedded Network of Halloysite Nanotubes: Effect of Polymer Cross-Linking on Rheological Properties and Microstructure

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4130
Author(s):  
Svetlana A. Glukhova ◽  
Vyacheslav S. Molchanov ◽  
Boris V. Lokshin ◽  
Andrei V. Rogachev ◽  
Alexey A. Tsarenko ◽  
...  
Keyword(s):  
3D Printing ◽  
Rheological Properties ◽  
Shear Thinning ◽  
Halloysite Nanotubes ◽  
Polymer Chains ◽  
Cross Linking ◽  
Saxs Data ◽  
Nanocomposite Hydrogels ◽  
Embedded Network ◽  
The Cross

Rapidly growing 3D printing of hydrogels requires network materials which combine enhanced mechanical properties and printability. One of the most promising approaches to strengthen the hydrogels consists of the incorporation of inorganic fillers. In this paper, the rheological properties important for 3D printability were studied for nanocomposite hydrogels based on a rigid network of percolating halloysite nanotubes embedded in a soft alginate network cross-linked by calcium ions. Particular attention was paid to the effect of polymer cross-linking on these properties. It was revealed that the system possessed a pronounced shear-thinning behavior accompanied by a viscosity drop of 4–5 orders of magnitude. The polymer cross-links enhanced the shear-thinning properties and accelerated the viscosity recovery at rest so that the system could regain 96% of viscosity in only 18 s. Increasing the cross-linking of the soft network also enhanced the storage modulus of the nanocomposite system by up to 2 kPa. Through SAXS data, it was shown that at cross-linking, the junction zones consisting of fragments of two laterally aligned polymer chains were formed, which should have provided additional strength to the hydrogel. At the same time, the cross-linking of the soft network only slightly affected the yield stress, which seemed to be mainly determined by the rigid percolation network of nanotubes and reached 327 Pa. These properties make the alginate/halloysite hydrogels very promising for 3D printing, in particular, for biomedical purposes taking into account the natural origin, low toxicity, and good biocompatibility of both components.

scholarly journals Liquid Metal Direct Write and 3D Printing: A Review

2020 ◽  
pp. 2000070
Author(s):  
Taylor V. Neumann ◽  
Michael D. Dickey
Keyword(s):  
3D Printing ◽  
Liquid Metal ◽  
Direct Write

Fabrication of a conductive composite structure with enhanced stretchability using direct-write 3D printing

2019 ◽  
Vol 6 (8) ◽  
pp. 085319
Author(s):  
Bijan Nasri-Nasrabadi ◽  
Akif Kaynak ◽  
Scott D Adams ◽  
Pejman Heidarian ◽  
Abbas Z Kouzani
Keyword(s):  
3D Printing ◽  
Composite Structure ◽  
Direct Write ◽  
Conductive Composite

scholarly journals Tunable structural color of bottlebrush block copolymers through direct-write 3D printing from solution

2020 ◽  
Vol 6 (24) ◽  
pp. eaaz7202 ◽  
Author(s):  
Bijal B. Patel ◽  
Dylan J. Walsh ◽  
Do Hoon Kim ◽  
Justin Kwok ◽  
Byeongdu Lee ◽  
...  
Keyword(s):  
3D Printing ◽  
Self Assembly ◽  
Three Dimensional ◽  
Size Control ◽  
Functional Materials ◽  
Domain Size ◽  
Direct Write ◽  
Processing Scheme ◽  
Solvent Vapor ◽  
Robust Processing

Additive manufacturing of functional materials is limited by control of microstructure and assembly at the nanoscale. In this work, we integrate nonequilibrium self-assembly with direct-write three-dimensional (3D) printing to prepare bottlebrush block copolymer (BBCP) photonic crystals (PCs) with tunable structure color. After varying deposition conditions during printing of a single ink solution, peak reflected wavelength for BBCP PCs span a range of 403 to 626 nm (blue to red), corresponding to an estimated change in d-spacing of >70 nm (Bragg- Snell equation). Physical characterization confirms that these vivid optical effects are underpinned by tuning of lamellar domain spacing, which we attribute to modulation of polymer conformation. Using in situ optical microscopy and solvent-vapor annealing, we identify kinetic trapping of metastable microstructures during printing as the mechanism for domain size control. More generally, we present a robust processing scheme with potential for on-the-fly property tuning of a variety of functional materials.

Integrating helicoid channels for passive control of fiber alignment in direct-write 3D printing

2021 ◽  
pp. 102419
Author(s):  
Nava Raj Khatri ◽  
Md. Nurul Islam ◽  
Peng-Fei Cao ◽  
Rigoberto C. Advincula ◽  
Wonbong Choi ◽  
...  
Keyword(s):  
3D Printing ◽  
Passive Control ◽  
Direct Write ◽  
Fiber Alignment
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