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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Characterization of anisotropic mechanical properties of polymer composites from a hybrid additive manufacturing-compression molding process using x-ray computer tomography

In this study, anisotropic stiffness tensors were reconstructed based on fiber orientation distributions obtained from X-ray computer tomography (xCT). A preform was manufactured via a big area additive manufacturing (BAAM) system with carbon fiber (CF) filled acrylonitrile butadiene styrene (ABS). The tailored preform from additive manufacturing (AM) was used in the compression molding (CM) process to produce a low-void high-performance thermoplastic composite panel. An xCT technique was employed to detect the fiber orientations in CF/ABS composites manufactured via three different methods: AM from BAAM, extrusion compression molding (ECM), and AM-CM. The anisotropic stiffness tensor was obtained from the composite panel manufactured via the three manufacturing methods (AM, ECM, and AMCM). A micromechanics theory was used to obtain the orthotropic stiffness tensors of the composite panels and compared with the experimental values. The predicted stiffness tensors of AM and AM-CM composite panels were used to study the deformation characteristics of a steering wheel during airbag deployment by performing finite element analysis (FEA). The approach developed in this study can be utilized for evaluating high-performance composites.

Pokkalla, Deepak↗
DOE OSTI2017

Charging and Release Mechanisms of Flexible Macromolecules in Droplets

We study systematically the charging and release mechanisms of a flexible macromolecule, modeled by poly(ethylene glycol) (PEG), in a droplet by using molecular dynamics simulations. We compare how PEG is solvated and charged by sodium Na{sup +} ions in a droplet of water (H{sub 2}O), acetonitrile (MeCN), and their mixtures. Initially, we examine the location and the conformation of the macromolecule in a droplet bearing no net charge. It is revealed that the presence of charge carriers do not affect the location of PEG in aqueous and MeCN droplets compared with that in the neutral droplets, but the location of the macromolecule and the droplet size do affect the PEG conformation. PEG is charged on the surface of a sodiated aqueous droplet that is found close to the Rayleigh limit. Its charging is coupled to the extrusion mechanism, where PEG segments leave the droplet once they coordinate a Na{sup +} ion or in a correlated motion with Na{sup +} ions. In contrast, as PEG resides in the interior of a MeCN droplet, it is sodiated inside the droplet. The compact macro-ion transitions through partially unwound states to an extended conformation, a process occurring during the final stage of desolvation and in the presence of only a handful of MeCN molecules. For charged H{sub 2}O/MeCN droplets, the sodiation of PEG is determined by the H{sub 2}O component, reflecting its slower evaporation and preference over MeCN for solvating Na{sup +} ions. We use the simulation data to construct an analytical model that suggests that the droplet surface electric field may play a role in the macro-ion–droplet interactions that lead to the extrusion of the macro-ion. This study provides the first evidence of the effect of the surface electric field by using atomistic simulations. .

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2018

Enhanced strength and toughness in ultra-fine grained 99.9% copper obtained by cryo-hydrostatic extrusion

Highlights: • Cryo-HE can increase the yield strength of Cu by more than threefold. • In cryo-HE of Cu, the grain refinement is stronger by 30% than in room-HE. • Cryo-HE with post-annealing effectively creates a bimodal microstructure in Cu. • Short-term post-annealing applied to cryo-HE-treated Cu can double its ductility. • Grain refinement with recrystallization results in a slight increase of Cu toughness. - Abstract: Ultrafine grained 99.9% Cu with enhanced strength and toughness was produced by hydrostatic extrusion conducted at the temperature of liquid nitrogen. The cryo-extruded Cu has a tensile yield strength of 490 MPa, hardness of 145 HV0.2, and tensile fracture toughness of 39.5 MPa m{sup 1/2}, which means that their values increased by 380%, 185% and ~10%, respectively, compared to those of the starting material. The significant strengthening is due to the strong grain refinement to 320 nm and the high energy of defects stored during the processing at liquid nitrogen temperature. The short term post deformation annealing doubles the ductility of material even by above 10% of the elongation to fracture at a slight expense of the yield strength (485 MPa). The observed behavior of Cu can be explained in terms of its low stacking fault energy, the susceptibility to dynamic recrystallization within the working zone of the extrusion die, and the triaxial strain components with the very large strain gradients, combined with the significant adiabatic heating effect active during the hydrostatic extrusion. The better homogeneity of the grain refinement and the higher efficiency of the distribution of defects and of the energy storage accompanied by the decreased dislocation mobility during the cryo hydrostatic extrusion contributed to the higher strength.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Design, fabrication, simulation, and testing of additively manufactured lattice-based copper heat sinks

Here, this study investigates the potential advantages of lattice structure-based bound metal material extrusion (MEX) 3D printing for fabricating high-performance copper heat sinks. Copper powder-filled polymer filaments, with a copper content of > 90 wt.%, were developed specifically for the bound metal MEX 3D printing process. Three types of structures—planar, strut, and surface lattices—were 3D printed to facilitate efficient heat transfer pathways within the heat sinks. Subsequent post-processing steps, including polymer removal and sintering, were performed to achieve dense copper parts. Hot isostatic pressing was further employed to enhance the sintered density from 93 to 98%. Finite element analysis (FEA) simulations were conducted to assess the heat transfer efficiency of the designs, and heat transfer experiments were performed using a custom setup to validate the simulation results. Additionally, this research explores the use of extended hold times during pre-sintering and a reduced atmosphere to enhance the %IACS values (electrical conductivity) and thermal performance of the bound metal MEX 3D printed copper heat sinks. The investigation combines experimental analysis, including simulations and heat transfer experiments, to gain insights into the structure-material property relationships and optimize the thermal performance of the printed heat sinks.

Ajjarapu, Kameswara Pavan Kumar [Oak Ridge Nationa↗
DOE OSTI2023

Recycled Glass Polypropylene Composites from Transportation Manufacturing Waste

In recent years there has been growing interest in developing recycling technologies for composites manufacturing scrap, process waste and end-of-life parts. The focus of this work was to establish processing routes and mechanical property bounds for glass-polypropylene (PP-GF) scrap from the production of parts for truck trailers, automobiles, and rail cars. This study considered PP-GF scrap and demonstrated extrusion-compression molding (ECM) as a viable route for the closed-loop manufacture of composite parts. The results were promising in terms of the strength and modulus retention of the PP-GF recyclate. The tensile strength and modulus was the highest for 50% and 66% recycled content, compared with 100% and 83% recycle content. The flexural strength and modulus of the 100% and 83% recycled compositions was higher than the 66% and 50% recycled content, respectively. The impact energy absorption of the PP-GF recyclate at at all fiber loadings was superior in absorbing energy compared with the incumbent (benchmark) plywood. This work is useful to designers seeking to incorporate recycled materials in their products.

Vaidya, Uday↗
DOE OSTI2022

Hybrid Curve Fitting For Reducing Motion Commands In Object Construction

Existing slicing software for additive manufacturing typically requires a triangulated mesh as its input. Triangulated meshes are approximate representations of exact CAD models. Despite the loss in dimensional accuracy, triangulated meshes are used because they are computationally easier to cross-section and offset than the exact geometry in CAD format. When a triangulated object is prepared, the resulting machine instructions include only linear motion commands. Numerous modern motion controllers can move in arc and spline motions; however, the absence of slicing software that supports curvature prevents these commands from being leveraged. To address this limitation, this paper presents a method for the hybrid reconstruction of arcs and splines as a post-processing step to traditional slicing. This method can greatly reduce the number of motion commands required to construct an object by printing smooth curved surfaces. This concise representation of tool-pathing allows for more even extrusion and is computed without a major impact on slicing time.

Wade, Charles↗
DOE OSTI2024

Towards a quantitative understanding of bonding in supersonic single particle impacts: A three-dimensional FIB-SEM exploration

Particle bonding is crucial to coating quality in cold spray, but it has been a challenge to accurately quantify bonding even in single particle impacts. This paper uses FIB-SEM to explicitly map the particle-substrate interface for Cu-on-Cu single microparticle impacts in a full 3D rendering that spans a wide range of impact velocities. This approach permits a detailed quantification of the total bonding area and all of its associated components. In addition to revealing why prior 2D characterization efforts have missed important details about impact bonding, these data quantitatively reveal the evolution of bonding from its onset at the “critical velocity” V cr (where bonding is generally poor, ∼6 %) to its peak at around 1.3‧V cr (where almost 90 % of the particle bonds). Further increase in the velocity to 1.5‧V cr and beyond finds the onset of hydrodynamic penetration and a decrease in bonding. These data then support the development of a simple analytical model based on oxide rarefication and extrusion of bare metal through gaps in the oxide layer as driving the development of bonding. As a result, the model reproduces the experiments and provides guidance on optimization of bonding as a function of material and process parameters.

Analytical methods↗
DOE OSTI2018

Preparation of cupric sulfate-based self-emulsifiable nanocomposites and their application to the photothermal therapy of colon adenocarcinoma

Highlights: • CuSO{sub 4} nanocomposites (NCs) were fabricated by hot-melt extrusion method. • Dispersion of CuSO{sub 4} in NCs was identified by several solid-state studies. • CuSO{sub 4} NCs exhibited improved photothermal therapeutic efficacies in Caco-2 cells. Nanocomposites (NCs) of cupric sulfate monohydrate (CuSO{sub 4}) were fabricated by hot-melt extrusion (HME) system equipped with twin screws. Micron-sized bulk powder of CuSO{sub 4} was dispersed in the mixture of surfactants (Span 80 and Tween 80) and hydrophilic polymer (polyethylene glycol (PEG) 6000) by HME process. Reduction of surface tension by surfactants and homogeneous dispersion in hydrophilic polymer along with HME technique were introduced to prepare CuSO{sub 4} NCs. Dispersion of CuSO{sub 4} NCs exhibited approximately 204 nm hydrodynamic size, unimodal size distribution, and positive zeta potential values. Encapsulation of CuSO{sub 4} in CuSO{sub 4} NCs and the physicochemical interactions between CuSO{sub 4} and pharmaceutical excipients were investigated by solid-state studies. Of note, CuSO{sub 4} NCs group exhibited higher antiproliferation efficacies, compared with bulk CuSO{sub 4}, in Caco-2 (human adenocarcinoma) cells at 75 and 100 μg/mL CuSO{sub 4} concentrations (p < 0.05). Also, near-infrared laser irradiation to CuSO{sub 4} NCs group elevated the antiproliferation efficacies, compared with non-irradiation group, in Caco-2 cells. After intravenous injection in mice, CuSO{sub 4} NCs did not show severe in vivo toxicities. Developed CuSO{sub 4} NCs can be one of promising candidates of photothermal therapeutic agents for colon cancers.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

RFA for Solar/Geothermal Hybrid Thermal Energy Storage Modeling: Cooperative Research and Development Final Report, CRADA Number CRD-16-646

Hyperlight Energy is an innovative concentrated solar power (CSP) company whose business charter is to commercialize a disruptively low-cost, CSP collector system that is ultimately for providing heat for solar thermal/geothermal hybrid power plants, process heat applications (e.g., enhanced oil recovery), and solar thermal power generation. Hyperlight's CSP collector system utilizes a linear Fresnel reflector (LFR) configuration. This LFR configuration consists of mirrors mounted in low-cost, precision plastic extrusions, which are integrated into raft assemblies and floated on low-cost, sealed waterbeds. Hyperlight's CSP collector technology has been developed under private equity investment, government grant and commercial funding. Hyperlight has been awarded a 1.5-million DOE COLLECTS contract with an additional 1.6 million in matched funds from private investment and the California Energy Commission. This DOE project will support the final steps of product development for bulk commercialization and deployment of the Hyperlight CSP collector system. The work will culminate in a final operational deployment at a commercially relevant site. Several such site options are currently under evaluation, including two geothermal sites. Hyperlight identified a very low-cost way to put renewable energy electrons on the grid at peak times, upgrading underutilized geothermal plants with Hyperlight's low cost CSP and thermal energy storage (TES). While Hyperlight's CSP collector work is maturing quickly for commercial pilot launch, an optimal TES system for solar thermal/geothermal hybridization needs to be evaluated and ultimately developed so Hyperlight can develop commercial retrofit projects at a scale of hundreds of megawatts of renewable energy power output at sites across the United States, followed by greenfield projects in a multi-GW sized market.

15 GEOTHERMAL ENERGY↗
DOE OSTI2012

Direct Solid-State Conversion of Recyclable Metals and Alloys

Friction Stir Extrusion (FSE) is a novel energy-efficient solid-state material synthesis and recycling technology capable of producing large quantity of bulk nano-engineered materials with tailored, mechanical, and physical properties. The novelty of FSE is that it utilizes the frictional heating and extensive plastic deformation inherent to the process to stir, consolidate, mechanically alloy, and convert the powders, chips, and other recyclable feedstock materials directly into useable product forms of highly engineered materials in a single step (see Figure 1). Fundamentally, FSE shares the same deformation and metallurgical bonding principles as in the revolutionary friction stir welding process. Being a solid-state process, FSE eliminates the energy intensive melting and solidification steps, which are necessary in the conventional metal synthesis processes. Therefore, FSE is highly energy-efficient, practically zero emissions, and economically competitive. It represents a potentially transformational and pervasive sustainable manufacturing technology for metal recycling and synthesis. The goal of this project was to develop the technological basis and demonstrate the commercial viability of FSE technology to produce the next generation highly functional electric cables for electricity delivery infrastructure (a multi-billion dollar market). Specific focus of this project was to (1) establish the process and material parameters to synthesize novel alloys such as nano-engineered materials with enhanced mechanical, physical, and/or functional properties through the unique mechanical alloying capability of FSE, (2) verifying the expected major energy, environmental, and economic benefits of FSE technology for both the early stage 'showcase' electric cable market and the anticipated pervasive future multi-market applications across several industry sectors and material systems for metal recycling and sustainable manufacturing.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2024

Toward Multiscale, Multimaterial 3D Printing

Biological materials and organisms possess the fundamental ability to self-organize, through which different components are assembled from the molecular level up to hierarchical structures with superior mechanical properties and multifunctionalities. These complex composites inspire material scientists to design new engineered materials by integrating multiple ingredients and structures over a wide range. Additive manufacturing, also known as 3D printing, has advantages with respect to fabricating multiscale and multi-material structures. The need for multifunctional materials is driving 3D printing techniques toward arbitrary 3D architectures with the next level of complexity. In this paper, the aim is to highlight key features of those 3D printing techniques that can produce either multiscale or multimaterial structures, including innovations in printing methods, materials processing approaches, and hardware improvements. Several issues and challenges related to current methods are discussed. Ultimately, the authors also provide their perspective on how to realize the combination of multiscale and multimaterial capabilities in 3D printing processes and future directions based on emerging research.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Direct writing of PVBVA/Ti 3 C 2 T x (MXene) triboelectric nanogenerators for energy harvesting and sensing applications

Triboelectric nanogenerators (TENGs) have gained recognition for their potential to convert mechanical energy into electrical energy, making them attractive for applications in healthcare, robotics, and human-device interfaces. However, many TENG devices rely on fluorinated polymers for high charge generation and involve complex fabrication processes, which limit their practicality and environmental sustainability. Here, we developed an eco-friendly composite of poly (vinyl butyral-co-vinyl alcohol-co-vinyl acetate) (PVBVA) and Ti 3 C 2 T x MXene for extrusion printing onto aluminum foil substrates, enabling the additive manufacturing of TENGs. Experimental results indicate that integrating 5.5 mg mL -1 of MXene (P-MX 5.5) into PVBVA resulted in a power density of 760 mW·m -2 , with simultaneous improvements in open-circuit voltage (129 %) and short-circuit current (250 %), demonstrating enhanced charge transfer efficiency. Beyond aluminum foil-based devices, we further explored the fully printed P-MX 5.5 TENG by utilizing silver ink electrodes, eliminating the need for aluminum foil. This fully printed, flexible TENG was successfully used for real-time human motion sensing, demonstrating its ability to detect activities such as walking, running, knee bending, and jumping. Collectively, our additively manufactured and sustainable PVBVA-MXene TENG composites, including both aluminum-based and fully printed versions, show promise for future energy harvesters, sensors, wearable electronics, healthcare, and robotic applications.

Additive manufacturing↗
DOE OSTI2018

Mechanical and degradation property improvement in a biocompatible Mg-Ca-Sr alloy by thermomechanical processing

Magnesium-based alloys have attracted interest as a potential material to comprise biomedical implants that are simultaneously high-strength and temporary, able to provide stabilization before degrading safely and able to be excreted by the human body. Many alloy systems have been evaluated, but this work reports on improved properties through hot extrusion of one promising alloy: Mg-1.0 wt% Ca-0.5 wt%Sr. This alloy has previously demonstrated promising toxicity and degradation properties in the as-cast and rolled conditions. In the current study extrusion causes a dramatic improvement in the mechanical properties in tension and compression, as well as a low in vitro degradation rate. Microstructure (texture, second phase distribution, and grain size), bulk mechanical properties, flow behavior, degradation in simulated body fluid, and effect on osteoblast cyctotoxicity are evaluated and correlated to extrusion temperature. In conclusion, maximum yield strength of 300 MPa (above that of annealed 316 stainless steel) with 10% elongation is observed, making this alloy competitive with existing implant materials.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Structural stability of thin overhanging walls during material extrusion additive manufacturing of thermoset-based ink

Recent developments have enabled material extrusion additive manufacturing of thermoset-based composite inks on the large scale. In addition, printing out-of-plane components is of broad interest to the polymer material extrusion community. Here, we address some of the challenges associated with both large-scale and out-of-plane thermoset material extrusion additive manufacturing by studying the height at which thin overhanging walls collapse. Walls at a range of overhang angles were printed until they collapsed. An optical camera captured the profile of each wall throughout the print, allowing the collapse height to be identified and the geometric fidelity to the programmed angle to be evaluated. Using previously measured rheological properties, predictive models were generated to approximate the collapse height and profile of the deflected walls. First, an analytical model was created to predict the height at which the walls would yield. The analytical model assumes the walls exhibit a perfectly linear profile; however, experiments proved this assumption to be false. Therefore, a finite element simulation was developed to account for the elastic deflection that occurs during printing. The finite element simulation predicts both the yield height and the deflected profile after the deposition of each layer. For the properties of the thermoset ink used here, the yield height predicted by the analytical model and finite element simulation are virtually identical. These predictions match experimental data reasonably well, but minor errors are observed. Accounting for the fully plastic moment appears to explain the small mismatch between experimental data and predictions. Additionally, the finite element simulation provides an excellent prediction of the deflected profile before the wall begins to collapse. Finally, by demonstrating that the collapse height and deflected profile of thin overhanging walls can be predicted, this work illustrates how the soft viscoelastic properties of thermoset-based composite inks limit the scale of a key feature required to print some nonplanar components. It also provides a basis to tailor in-process curing systems to suppress deflection and collapse of thin overhanging walls.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Fused filament fabrication of thermoplastic polyurethane composites with microencapsulated phase-change material

Here, the present study examines the thermal energy storage (TES) effectiveness and printability of microencapsulated phase-change material (MEPCM) combined with thermoplastic polyurethane (TPU) for fused filament fabrication (FFF). Two formulations were assessed: 24D MEPCM, which changes phase at 24 ° C, compounded with TPU pellets and 43D MEPCM, which changes phase at 43 ° C, integrated with TPU powder. These combinations are designed to evaluate the effectiveness of the form of the TPU (pellets versus powder) in the FFF process. The investigation includes a comprehensive analysis of thermal characteristics, encompassing phase-change temperature, latent heat of fusion, thermal conductivity, and thermal decomposition, which are assessed through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Additionally, mechanical properties, including stress-strain behavior, are examined to evaluate material suitability for TES applications, while microstructural visualization is used to provide deeper insights into material performance, structural integrity, and the quality of printed components. The 24D MEPCM and TPU pellets formulation experienced a significant loss of approximately 39.6% of PCM during filament extrusion and printing, resulting in a reduced effective latent heat. Therefore, further characterization of the pellet formulation was discontinued due to excessive leakage. In contrast, the 43D MEPCM and TPU powder formulation demonstrated minimal PCM loss, with the 60 wt.% composition achieving an effective latent heat of 132 J/g. This value represents the highest effective latent heat currently documented in the literature for PCM-polymer-composite materials produced using an FFF-based additive manufacturing process.

25 ENERGY STORAGE↗
DOE OSTI2014

Deformation Behavior of Solid-Solution-Strengthened Mg-9wt%Al Alloy: In-Situ Neutron Diffraction and Elastic-Viscoplastic Self-Consistent Modeling

In situ neutron diffraction and elastic viscoplastic self-consistent (EVPSC) modeling have been employed to understand the deformation mechanisms of the loading unloading process under uniaxial tension in a solid-solution-strengthened extruded Mg 9 wt.% Al alloy. The initial texture measured by neutron diffraction shows that the {00.2} basal planes in most grains are tilted around 20 30 from the extrusion axis, indicating that basal slip should be easily activated in a majority of grains under tension. Non-linear stress strain responses are observed during unloading and reloading after the material is fully plastically deformed under tension. In situ neutron diffraction measurements have also demonstrated the non-linear behavior of lattice strains during unloading and reloading, revealing that load redistribution continuously occurs between soft and hard grain orientations. The predicted macroscopic stress strain curve and the lattice strain evolution by the EVPSC model are in good agreement with the experimental data. The EVPSC model provides the relative activities of the available slip and twinning modes, as well as the elastic and plastic strains of the various grain families. It is suggested that the non-linear phenomena in the macroscopic stress strain responses and microscopic lattice strains during unloading and reloading are due to plastic deformation by the operation of basal a slip in the soft grain orientations (e.g. {10.1}, {11.2} and {10.2} grain families).

Lee, Sooyeol↗
DOE OSTI2023

Strength-conductivity synergy via lean alloy design: A study on novel solid stir extrusion of an Al-2Cu-0.1 Nb-0.15Zr (~wt.%) alloy

Aluminum alloys find wide applications in power and transmission cables, and electrical conductors due to their advantageous properties of high electrical conductivity, and lower cost per unit. However, the lower tensile strength compared to copper poses a challenge for the mechanical stability of aluminum-based cables. In this study, we addressed this issue by adopting a process-based alloy design approach, creating a lean alloy with a dilute composition of Al-2Cu-0.1 Nb-0.15Zr (~wt.%). Here, the alloy was processed using a friction stir based novel SolidStir® (SSE) technique, followed by low-temperature aging. The resulting aluminum wire exhibited improved strength (240 MPa) while simultaneously enhancing electrical conductivity (64%IACS). The study employed computational simulations (Thermocalc) and experimental techniques (differential scanning calorimetry and transmission electron microscopy) to thoroughly investigate the microstructure. Microstructural examinations revealed that the precipitation kinetics in SSE and SSE+aged conditions played a significant role in enhancing strength and electrical conductivity. These findings demonstrate the successful achievement of high strength and high electrical conductivity in aluminum wire through a lean alloy design approach.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Coarse-Grained Simulations of Polyrotaxane Hydrogels under Quiescent and Shear Conditions

Cyclodextrin-based polyrotaxanes (PR) form hydrogels in water through cyclodextrin (CD) aggregation and crystallization. These networks can break under shear flows, making them versatile platforms for extrusion-based 3D printing. To optimize the material properties of 3D-printed PR gels, a microscopic understanding of the structural evolution during 3D printing is necessary. Here, we employ coarse-grained (CG) simulations to reveal the PR assembly process at the molecular level. Our simulations reproduce the experimental crystal morphologies of PR at varying concentrations and chain lengths under quiescent conditions. Using nonequilibrium simulations, we show shear flow ruptures crystalline domain connectivity in PR gels and stacks the lamellae in the gradient direction, allowing the materials to flow during 3D printing. After the cessation of flow, the anisotropic crystal alignment and absence of available dangling PR diminish the intercrystal connectivity. The printed materials are therefore mechanically weaker than the pristine hydrogels, in agreement with experimental results. Nonetheless, by relating the microscopic structural evolution with viscoelastic properties of PR gels and solutions, we elucidate how flow conditions and sample composition affect the 3D printing performance of PR hydrogels.

Smith, Cameron D. [Dartmouth College, Hanover, NH ↗