2026 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2026): Engineering Printable Polymer Systems: Formulation, Rheology, and Process Windows
Program Organizers: David Leigh, University of Texas at Austin
Monday 1:30 PM
August 3, 2026
Room: Zlotnick Ballroom 2
Location: AT&T Center
1:30 PM
Developing Rheology Modified Resins for Inkjet Printing of Dicyclopentadiene: Benjamin Skultety1; Meghan Kiker1; Adam Cook1; Steven Digregorio1; Leah Appelhans1; 1Sandia National Laboratories, Albuquerque, NM
Material jetting is an additive manufacturing technique that can fabricate complex parts with multiple material compositions and high resolution. Formulation of inks for material jetting requires optimization of properties like density, viscosity, and surface tension for optimal droplet formation. Commonly, inks for material jetting will contain diluents to lower the viscosity. However, in some cases, such as dicyclopentadiene (DCPD), the neat monomer’s viscosity and surface tension are too low for optimal jetting. We explore different approaches to optimize DCPD inks in order to achieve an ink formulation suitable for jetting. We investigate approaches including the addition of low molecular weight liquid rubbers, the addition of DCPD oligomers synthesized via frontal ring-opening metathesis oligomerization (FROMO), and rapid viscosity modification, where a low loading of catalyst is added and then quenched, followed by a latent catalyst for polymerization during printing.
1:50 PM
Investigating the Reliable Jetting of High-viscosity Polymers Using Piezo-driven Jet Valve
: Mahjabin Moon1; Manas Vyas1; Danielle Miller1; Jonathan Boreyko1; Christopher Williams1; 1Virginia Tech
Inkjet-based material jetting additive manufacturing (MJT) enables high-resolution and high-throughput material deposition. However, stable droplet ejection of high-viscosity materials remains challenging due to difficulties in maintaining reliable jet formation and droplet detachment within the constraints of conventional piezoelectric drop-on-demand jet heads. In this study, the jetting behavior of truly high-viscosity (low-Z) materials is investigated using a piston-driven jet valve-based material jetting system. The inverse Ohnesorge number was used as a framework to evaluate printability by measuring viscosity and surface tension under printing-relevant conditions and correlating these properties with high-speed imaging of jet formation, ligament thinning, and droplet detachment. The results show that a combination of controlled heating, tuned pulse duration, and high-energy pulsed piston-driven actuation enables stable jetting of materials that are traditionally difficult to print, thereby demonstrating the potential of emerging piston-driven valve-based jetting systems for reliable deposition of high-viscosity materials.
2:10 PM
Coupled Effects of Nozzle Diameter and Temperature on the Printability of Carbon Black/LIR Sensor Inks in Direct Ink Writing: TANUBEN AMRUTBHAI CHAUDHARY1; Anahita Emami1; 1Texas State University
Direct ink writing is a useful method for making soft and flexible sensors, but good print quality depends on choosing the right printing settings. This study looks at how nozzle diameter and nozzle temperature work together during printing of a Carbon Black/LIR elastomer ink. The ink is designed for conductive rubber sensors, and the study focuses on line width, shape stability, and electrical behavior of the printed traces. By testing a small set of nozzle sizes and temperatures, we examine how these two settings affect ink flow, filament shape, and print consistency. The results are used to identify a practical printing window that gives stable deposition and reliable sensor paths. This work gives a simple process guide for printing carbon-filled elastomer sensors with better accuracy and repeatability.
2:30 PM
Dual-Component Direct Ink Write of Polyurethane Foams: McGinley Zastrow1; Daniel Rau1; 1University of Wyoming
We develop a novel dual-component direct ink write (DC-DIW) additive manufacturing (AM) process that mixes a two-part polyurethane foam in the nozzle during extrusion and selectively deposits the ink layer-by-layer to build 3D foam structures. Unique to this process, the material foams and expands 2-3x in size while simultaneously curing after deposition. This transient expansion and curing process is understood and controlled to produce high-quality 3D foam parts. We tune resin rheology through material formulation and investigate how it couples to printing behavior, foaming kinetics, cellular structure, and final mechanical properties. By balancing foaming kinetics and printability, we achieve high-fidelity AM while preserving the foam's inherent soft and elastic properties, producing parts with a compressive modulus below 100 kPa while maintaining highly elastic behavior. These advances work towards the AM of architected foams for impact protection, vibration damping, and thermal management applications.
2:50 PM
A Rheological Approach to Measuring Cure Depth of Soft Photopolymers: Daniel Rau1; CHARLES YEBOAH1; 1University of Wyoming
Vat photopolymerization (VP) builds 3D structures through the layer-by-layer photocuring of liquid photopolymer resins, and the accurate measurement of UV exposure versus cure depth is critical for high-fidelity printing. However, measuring the cure depth of soft resins is extremely difficult as conventional measurements deform the soft and thin films, corrupting the measurement. We advance a photorheology-based approach to measure the cure depth of soft elastomers under process-relevant UV irradiance and wavelengths. To ensure accuracy, we replace the conventional normal-force based measurements with a torque-based detection method to eliminate compression of the soft materials. Because photocuring behavior is highly dependent on the specific UV source used, we also explore using resin absorption and UV source spectra to translate curing behavior between different UV sources. Together, these advances help translate rheometer measurements of cure depth to printer-specific conditions, supporting reliable VP of soft photopolymers across a range of UV sources.
3:10 PM Break
3:30 PM
Optimizing Soft and Stretchable Elastomers for Vat Photopolymerization: Ram Mahato1; Daniel Rau1; 1University of Wyoming
Soft and stretchable photopolymer resins for vat photopolymerization (VP) are needed for soft robotics, flexible electronics, and biomedical devices, but their development is limited by both poor mechanical performance and printing quality. To address these challenges, we optimize an acrylate-based elastomeric resin through the systematic incorporation of multifunctional thiols and silicone-based additives. Thiol incorporation reduces modulus from 34 to 8.0 kPa while increasing elongation at break from 300% to over 1040%. However, the thiol-modified resins are very sticky resulting in high recoating forces that cause warping and print failure. Adding silicone-based additives reduces peel stresses during recoating by up to 53% and improves print quality. The optimized formulation containing both thiols and silicone-based additives achieves dimensional fidelity errors as low as 3%. Together, the additives provide independent control over mechanical properties and adhesion behavior to enable the reliable VP printing of highly stretchable elastomers with high geometric fidelity.
3:50 PM
Enabling Accessible Olefin Metathesis 3D Printing Using Photoacid Activated Catalysts: Meghan Kiker1; Hayden Fowler1; Alex Commisso1; Anna Vaisman2; Haley Jones3; Brianna Addison1; Zhenchuang Xu4; Asaf Nissenbaum5; Gabriel Lemcoff2; Leah Appelhans1; Samuel Leguizamon3; Yuval Vidavsky5; 1Sandia National Lab; 2Ben-Gurion University of the Negev; 3Savannah River National Lab; 4University of Illinois at Urbana-Champaign; 5Soreq Nuclear Research Center
Limited materials available for light-based additive manufacturing methods have driven research into new chemistries beyond commonly used acrylate-based resins. Recently developed photoinitiated ring-opening metathesis polymerization (photoROMP) is a promising technique due to its ability to produce a wide range of polymers with superior mechanical properties and chemical stability. However, current photoROMP resins typically exhibit short pot lives and longer activation times that make them challenging to implement for some additive manufacturing applications. In this work several acid-activated ruthenium catalysts were evaluated in dicyclopentadiene resins for digital light processing (DLP) vat photopolymerization 3D printing with commercially available PolCat identified as an ideal catalyst. In combination with a photoacid generator, PolCat was used to demonstrate long lived resins with low activation times, allowing for larger and complex prints with a wide array of material properties.
4:10 PM
High-Performance PAEK-PEI Blends investigated Using Active-Filament Mixing Fabrication: Joshua Green1; Daniel Hernandez1; Ian Rybak1; Joseph McKee1; 1University of Texas at El Paso
High-performance thermoplastics for high-temperature applications are in increasing demand, with polyetheretherketone (PEEK), a member of the polyaryletherketone (PAEK) family, among the most widely used. However, PAEK polymers remain difficult to process via additive manufacturing due to poor printability and weak interlayer adhesion. This study investigates blends of PAEK and polyetherimide-rich (PEI) thermoplastics fabricated using active filament mixing fabrication (AFMF), a modified fused filament fabrication technique that enables in situ material blending. Tensile specimens were printed in open air and tested parallel and perpendicular to the build direction. Compared to neat PEEK, optimized blends showed improved printability, enhanced tensile properties, reduced warping, and significantly improved interlayer adhesion. These results demonstrate the versatility of AFMF to investigate new blends of thermoplastics and indicates that such blends of PAEK and PEI-rich thermoplastics may be a useful formulation for overcoming the persistent challenges in printing high-performance thermoplastics.
4:30 PM
Development and Shape Memory Characterization of a High-Entropy & Biodegradable Polymer Blend for Fused Granulate Fabrication: Estefania Mireles Flores1; David Roberson1; 1University of Texas El Paso
This work details the development of a fully biodegradable, high-entropy polymer (HEP) blend for fused granulate fabrication (FGF) and 4D printing. Dynamic mechanical analysis (DMA) was employed to establish benchmarks for the material system, utilizing the glassy onset temperature and maximum tan δ temperature to determine approximate deformation and recovery temperatures. Thermomechanical cycling using a micro tensile tester equipped with a thermal chamber and a digital image correlation (DIC) system to capture localized strain data was used to determine critical parameters. A Python-based automation workflow was developed to process complex data from the DIC and tensile outputs. This pipeline enables the precise calculation of the shape recovery ratio (Rr), shape fixation ratio (Rf), and shape memory index (SMI). This research provides a scalable methodology for engineering high strength, “smart” biodegradable materials, contributing to the reduction of polymer waste through enhanced material durability and functional 4D printing performance.