2024 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2024): AM of Composites and Other Materials III
Program Organizers: Joseph Beaman, University of Texas at Austin
Wednesday 8:00 AM
August 14, 2024
Room: Salon A
Location: Hilton Austin
Session Chair: Emmanuel Bamido, University of Texas at Austin
8:00 AM
Fabrication of Elastomeric Shape-Stabilized Phase Change Materials through Vat Photopolymerization: Yiqun Fu1; Timothy Long2; Christopher Williams1; 1Virginia Tech; 2Arizona State University
Shape-stabilized phase change materials (ss-PCMs) offer excellent thermal energy storage/release capabilities through a phase transition without deformation of the part shape. Additive manufacturing (AM) presents a promising solution to fabricate complex ss-PCM geometries designed for effective energy management. However, most of the AM fabricated ss-PCMs are brittle and suffer from compromised thermal performance. Here, we present vat photopolymerization (VP) of an elastomeric ss-PCM, in which part geometry is defined by photocuring an acrylic scaffold around latex particles that are suspended in the resin. A thermal post-process coalesces the particles forming a semi-interpenetrating network. In this work, we demonstrate fabrication of intricate geometries of styrene-isoprene-styrene block copolymers supported ss-PCMs (SIS-ss-PCM) with polyethylene glycol (PEG) as encapsulated PCM. The effects of PEG loading on thermal performance and mechanical properties of the SIS-ss-PCM are investigated. The SIS-ss-PCMs with 20 wt. % PEG exhibit latent heat of 32.14 J/g and enthalpy efficiency of 99.81%.
8:20 AM
Development of a Low-viscosity, UV-curable PDMS Formulation for Vat Photopolymerization: Hongtao Song1; Roxana Carbonell1; Martha Leach1; Carolyn Seepersad1; 1Georgia Insitute of Technology
Polydimethylsiloxane (PDMS) elastomers are silicone rubbers widely used in industrial and academic applications. Increasing levels of research have focused on adopting PDMS to Vat Photopolymerization (VPP) in recent years. Unfilled PDMS exhibits relatively low mechanical strength and stiffness. Adding reinforcement particles enhances its mechanical properties, but it also results in greatly increased resin viscosity, which raises serious challenges in printing with the resin in Vat Photopolymerization. The mechanical properties of PDMS are governed by the average molecular weight (Mn), the concentration of crosslinking chemical bonds, and the concentration of the reinforcement fumed silica nanoparticles. This work investigates the influence of the previously mentioned factors on the resultant mechanical properties. The results offer guidelines for designing UV-curable PDMS formulations with desired mechanical properties while maintaining a relatively low viscosity for ease of operation.
8:40 AM
Bead-weaved Layered Prints for Improved Interlayer Adhesion in Additive Manufacturing: Arianna Villegas1; 1W.M. Keck Center for 3D Innovation
Additive manufacturing (AM) with polymers is widely adopted in industries such as aerospace, automotive, healthcare, and consumer products, due to benefits like rapid prototyping, diverse materials, cost efficiency, and complex manufacturing capabilities. AM's quick, economical approach eliminates tooling and minimizes waste, promoting sustainability and reducing inventory through on-demand production. However, polymer AM faces challenges with interlayer adhesion, impacting mechanical properties. This has spurred research into improving interlayer bonding in Fused Deposition Modeling (FDM), leading to innovations like bead-weaved layered prints. These techniques aim to leverage AM's anisotropic mechanical properties by aligning material deposition with expected strain fields using multi-axis 3D printing. We propose testing two hypotheses: 1) Bead weaving will change the shear and tensile stresses in AM parts, enhancing structural integrity. 2) Alternating deposition patterns will reduce stress concentrations at interfaces, achieving uniform mechanical properties, thus broadening the practical applications of polymer-based AM.
9:00 AM Cancelled
Development of Lithium-Based Solid-State Electrolytes Using Direct-Ink Write Process: John Obielodan1; Jacob Ferguson1; Zhezhen Fu2; 1University of Wisconsin-Platteville; 2Pennsylvania State University Harrisburg
Solid-state electrolytes are being developed for the solid-state batteries using Direct-Ink Write process. In this work, colloidal pastes of ceramic type Li-garnet solid-state electrolyte (Li6.75La3Zr1.75Ta0.25O12) in photocurable resin were used to 3D print test samples. The pastes demonstrated promising printing behaviors that allow the fabrication of various structures. The samples were sintered at temperatures between 1100oC and 1250oC for durations ranging from 2 to 6 hours. X-ray diffraction shows that they maintain single cubic Li-garnet phase. They were densifiable to high relative densities based on SEM observations. The ionic conductivities of the samples were obtained. The results shows that 3D printing is a promising route for fabricating solid-state electrolytes for solid-state batteries.
9:20 AM
Functional Nanomaterial Inks for 3D-Printed Electronics via a Scalable Continuous-Flow Synthesis Method: Robyn Worsley1; Anil Bastola1; Richard Hague1; Christopher Tuck1; Edward Lester1; 1University of Nottingham
The fabrication of electronic devices and embedded circuitry components requires functional materials beyond those typically used in 3D-printing for rapid prototyping and the production of end-use structural parts. For ink-based additive manufacturing, this functionality is often achieved through electronically-active nanofillers dispersed within solvents or polymeric resins. Continuous-flow hydro- and solvothermal production methods generate a wide variety of functional nanomaterials; the particles are suspended in solution and delivered at scale, with a high degree of control over product characteristics, rendering this synthesis approach complementary to functional ink formulation work. Here, a counter-current nozzle reactor within a bench-scale sub/supercritical continuous-flow system is used to synthesise a range of nanoparticles with desirable electronic properties, including magnetic and dielectric materials. In-flow surface functionalisation is explored, enabling immediate and stable dispersion of the synthesised particles within various solvents and UV-curable resins. The resultant inks were successfully printed using both material jetting and vat photopolymerisation techniques.
9:40 AM
Granulation of Fine Eggshell Powder into Granules for Binder Jetting Additive Manufacturing of Carbon-Capture Components: Md Shakil Arman1; Fahim Khan1; Mostafa Meraj Pasha1; Jackson Sanders1; Zhijian Pei1; 1Texas A&M University
This study aims to compare the properties of granulated eggshell powder with raw eggshell powder to produce carbon-capture components using binder jetting additive manufacturing for fighting global warming. Uneven powder spreading is a common problem in powder bed additive manufacturing that affects the overall quality of printed parts. Granulating the powder can enhance its flowability, making it easier to dispense and spread evenly across the build platform. For the first time, we will prepare the granulated eggshell powder by spray freeze drying and study the effects of its parameters (solid loading, spraying pressure, etc.) on the properties (granule size and flowability) of the resulting granulated powder. Specific surface area and pore size distribution of the granulated and raw eggshell powder will be measured and compared by BET N2 Isotherm process. From this data an initial observation of the carbon capture capacity can be made.
10:00 AM Cancelled
Microstructure, Mechanical Properties, and Oxidation Resistance of NiCoCrAlFe High Entropy Alloy Manufactured via Laser Directed Energy Deposition: Fan Zhou1; Xingru Tan1; Zhichao Liu1; 1West Virginia University
In this study, high entropy alloy (HEA) composed of five elements (Al, Co, Cr, Fe, Ni) with different proportions was manufactured by laser directed energy deposition. The microstructure, mechanical properties, and oxidation resistance of those printed HEA parts were investigated. Firstly, ten different elemental compositions were selected by machine learning based on the simulated oxidation resistance performance. Then pure element powers were mixed by ball milling according to the chosen proportions. After optimizing the printing parameters, block samples were fabricated and then characterized by optical microscopy, scanning electron microscopy, X-Ray diffraction analysis, hardness testing, and oxidation resistance evaluation. The experimental oxidation results are consistent with the simulation and the superior oxidation resistance performance of additive manufactured HEA is comparable to the existing commercial materials.
10:20 AM Break
10:40 AM
Rapid 3D Printing of Electro-Active Hydrogels: Wenbo Wang1; Xiangfan Chen1; 1Arizona State University
Electroactive hydrogels (EAH) have gained prominence for their unique ability to change shape or size under an electric field, finding applications in biosensors and soft actuators. This study focuses on a tunnelable EAH tailored for high-resolution 3D printing via the micro continuous liquid interface production (µCLIP) process. The resin formulations mainly involve acrylic acid (AA) and 4-hydroxybutyl acrylate (4-HBA). AA, with its carboxyl groups, introduces electroactuation, generating osmotic pressure in the hydrogel matrix. This results in swelling, inducing bending towards the cathode, accentuating the material's responsiveness. In contrast, 4-HBA offers mechanical resilience, providing an elastic backbone, and ensuring the hydrogel's applicability. Our results illustrate the hydrogel's strength, flexibility, and bending capabilities across varied compositions and electric field strengths. Notably, the µCLIP process enabled the 3D printing of our EAH into sophisticated structures. The combination of AA's electro-responsive traits with 4-HBA's durability has birthed a material with vast practical implications.
11:00 AM
Spreadability of Raw Sand in Binder Jet Additive Manufacturing: Examining Feasibility Using Numerical Methods: Ibrahim Al Qabani1; Goldberg Karin2; Hossein Taheri3; Drew Snelling3; Rafael Quirino3; Genevieve Baudoin2; Scott Thompson1; 1University of Missouri; 2Kansas State University; 3Georgia Southern University
In binder jet additive manufacturing (BJAM), the consistency and homogeneity of the deposited powder layer directly influence the density and dimensional accuracy of the green part. This study investigates the printability of unrefined sand using roller spreading. The Discrete Element Method (DEM) was used to simulate the BJAM process to evaluate powder bed homogeneity and density under various operating conditions. Utilizing high-performance computing and graphics processing unit (GPU) clusters, highly-resolved simulations were performed with up to 300,000 grains. DEM simulations were executed by reconstructing particle shapes using two-dimensional images obtained through experiments. Numerical results indicate that peak powder bed density occurs at lower translational velocities, coinciding with a minimal fraction standard deviation. Powder layer thicknesses exceeding 200 micrometers were found to prevent particle jamming and subsequent void spaces across the deposited layer. This study shifts focus from high-quality foundry sand to raw earth sand for potential use in remote BJAM.
11:20 AM
3D Printing Tris 2-Isocyanurate Triacrylate with Cyanate Ester Resins for Interpenetrating Networks to Enhance Thermo-mechanical Properties: Saqlain Zaman1; Sergio Favela1; Nicolas Herrera1; Yirong Lin1; 1University of Texas at El Paso
Cyanate ester (PT-30) resin boasts remarkable thermal and mechanical properties, including a high heat distortion temperature and glass transition temperature (Tg), along with exceptional mechanical characteristics. Similarly, the homopolymer of tris(2-hydroxyethyl)isocyanurate triacrylate (T-acrylate) exhibits a superior Tg compared to other acrylates. By combining PT-30 and T-acrylate, interpenetrating polymer network (IPN) is formed through dual curing mechanisms. A formulated ink comprising PT-30, T-acrylate, photoinitiator, and rheological additive underwent UV light and thermal curing. Characterization via Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Mechanical Analysis (DMA), Thermo Gravimetric Analysis (TGA), and tensile testing confirmed the successful IPN formation, enhancing mechanical properties and elevating the Tg. The study underscores the viability of Ink Extrusion 3D printing with cyanate ester resin and T-acrylate, offering high-performance structural solutions applicable in aerospace, defense, and microelectronics, with structures exhibiting ~80% tensile strength retention at 200°C and a high Tg of 349±3°C.
11:40 AM
Effect of Aging on the Mechanical Properties of Methacrylate 3D Printed Parts: Christian Rivera1; C. Hasbrouck1; Joseph Fisher1; Joseph Bartolai1; Simon Miller1; 1Applied Research Labotory
The effects of natural and artificial aging processes on the mechanical properties of commercially available methacrylate photopolymer parts are explored in this paper. The specimens are produced with GreyPro resin on a FormLabs Form 3L stereolithography (SLA). A design of experiments was developed and the specimens were evaluated for: time elapsed since printing (green, 1 and 3 months), storage condition (ambient laboratory environment, darkened container), and aging process (ambient laboratory lighting, manufacturer suggested post-cure). The mechanical properties were characterized using uniaxial quasi-static tensile and microhardness testing to evaluate the experimental design. Additional microhardness maps were developed through the cross-section of bisected cubes to evaluate the depth-of-cure and spatial gradients due to the aging process. After statistical evaluation, preliminary results highlight the time, storage, and aging sensitivities of SLA-printed methacrylate photopolymer parts’ mechanical properties in both bulk (tensile) and local (microhardness) – discussion on the variance of properties will be discussed.