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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Effects of PLA/PHB Blend Ratio and Wood Flour Loading on the Melt Rheology and Thermomechanical Properties of Biobased Polymer Composites

The development of sustainable, biobased polymer composites is crucial for reducing supply chain dependence on fossil fuels. A major challenge lies in understanding and predicting the processability of these sustainable material alternatives, which directly impacts large-scale manufacturing. Here, this study systematically investigates the effect of poly(lactic acid) (PLA)/polyhydroxybutyrate (PHB) blend ratios and wood flour (WF) loadings on the thermal, rheological, and mechanical properties of the composites. Composites were prepared via melt compounding and characterized by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), oscillatory shear melt rheology, tensile testing, and scanning electron microscopy. Results showed that increasing the PHB content lowered the glass transition temperature, while higher PHB and WF loadings decreased thermal stability. Complex viscosity decreased with increasing PHB in 0 and 10% WF, whereas it increased in 20% and 30% WF for PHB-rich blends (80/20 and 70/30 PLA/PHB) due to stronger filler interactions with flexible PHB chains. At 30% WF, PHB-containing composites also showed elastic dominance with G′ higher than G″. This behavior was confirmed by van Gurp–Palmen plots, where the phase angle decreased with increasing PHB and WF loadings. WF addition also shifted Cole–Cole plots away from semicircular terminal relaxation, while time–temperature superposition validity was maintained, confirming that polymer chain dynamics continue to dominate melt behavior. Young’s modulus increased with WF loading, while tensile strength and toughness decreased due to weaker interfacial adhesion between the matrix and the filler. Interestingly, 10% WF systems containing PHB exhibited the highest toughness among all of the filled systems, indicating synergistic reinforcement from WF fillers and PHB-induced ductility. Overall, melt rheology effectively captured the internal structure and stiffness of the composites as the formulation changed, reinforcing the concept that the PLA/PHB ratio and WF content can be tuned to adjust melt elasticity and balance mechanical property trade-offs for targeted applications.

melt rheology↗
DOE OSTI2016

Mechanical Response of DNA–Nanoparticle Crystals to Controlled Deformation

The self-assembly of DNA-conjugated nanoparticles represents a promising avenue toward the design of engineered hierarchical materials. By using DNA to encode nanoscale interactions, macroscale crystals can be formed with mechanical properties that can, at least in principle, be tuned. Here we present in silico evidence that the mechanical response of these assemblies can indeed be controlled, and that subtle modifications of the linking DNA sequences can change the Young’s modulus from 97 kPa to 2.1 MPa. We rely on a detailed molecular model to quantify the energetics of DNA–nanoparticle assembly and demonstrate that the mechanical response is governed by entropic, rather than enthalpic, contributions and that the response of the entire network can be estimated from the elastic properties of an individual nanoparticle. The results here provide a first step toward the mechanical characterization of DNA–nanoparticle assemblies, and suggest the possibility of mechanical metamaterials constructed using DNA.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

High-Spatial-Resolution Quantitative Chemomechanical Mapping of Organic Composite Cathodes for Sulfide-Based Solid-State Batteries

Understanding the chemo-mechanical behaviors of electrodes, particularly at the electrode/electrolyte interfaces, is critical for improving the performance of all-solid-state batteries. However, due to the instability of electrolyte materials under ambient conditions, such characterizations are challenging, particularly for sulfide-based all-solid-state batteries. Herein, by combining time-of-flight secondary-ion mass spectroscopy (ToF-SIMS) and in-SEM nanoindentation measurements, a systematic quantitative investigation of the chemo-mechanical behaviors of pyrene-4,5,9,10-tetraone (PTO) /Li 6 PS 5 Cl composite cathodes is carried out. Chemical and quantitative mechanical information of the composite cathode were collected with high spatial resolution after developing and implementing an air-free characterization protocol. By directly connecting the Young’s modulus and hardness with the Li distribution in the composite cathode, a comprehensive chemo-mechanical mapping of the PTO/ Li 6 PS 5 Cl composite cathode has been established. Furthermore, this work improves our knowledge of the critical chemo-mechanical phenomena that occur at the cathode/electrolyte interfaces in all-solid-state batteries.

25 ENERGY STORAGE↗
DOE OSTI2024

Ductile Glassy Polymer Networks Capable of Large Plastic Deformation and Heat-Induced Elastic Recovery

Many thermoplastic polymers are ductile by combining strength and large deformations. These deformations are irreversible - known as plastic deformation. Elastomers can deform reversibly but have low strength. To this end, we developed glassy and ductile polyamide networks capable of large plastic deformation (>200% strain) and high strength (~50 MPa tensile strength and ~1500 MPa Young’s modulus), similar to those of polyolefins and Nylon-66. We discovered that hydrogen bonding between meta-phthalamide groups was essential to the ductility. Since these polyamide networks are covalently bonded, we demonstrated their unique durability by repeatable elastic recovery at elevated temperatures, exhibiting indifferent tensile properties in each cycle. Furthermore, when we fixed the strain during the elastic recovery, these polyamide networks actuated stresses of 9–18 MPa, among the highest reported in shape-memory polymer actuators. Here, we envision these ductile, glassy polymer networks as promising alternatives to ductile thermoplastics, given the combined benefit of ductility and durability.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Stereolithography 3D Printing of Lignin-Reinforced Composites with Enhanced Mechanical Properties

Due to the availability, biodegradability, and biological effects, lignin has emerged as an interesting alternative to petroleum-based compounds for developing sustainable chemicals, materials, and composites. In this study, lignin at various concentrations was incorporated into methacrylate resin via solution blending to fabricate lignin-reinforced composites using stereolithography apparatus three-dimensional printing. Softwood kraft lignin in the amounts of 0.2, 0.4, 0.5, 0.8, and 1.0 wt % in the methacrylate resin was used as a printing ink, and the gel contents and relative contents of the residual resin in the printed samples with various lignin concentrations were measured. The effects of the lignin on the ultimate mechanical properties of the non-postcured and postcured printed composites were determined. The tensile testing results revealed that the incorporation of lignin in the composite increased the tensile strength by 46–64% and Young’s modulus by 13–37% for the postcured printed composites compared with that of the control sample (no lignin added). Employing a 0.4 wt % softwood kraft lignin, the tensile strength of the postcured printed composite reached the highest value of 49.0 MPa, which was a 60% increase in comparison to that of the control sample with 30.7 MPa. Scanning electron microscopy images of the fracture samples illustrated that the lignin-incorporated composites exhibited a rougher fracture surface that can presumably dissipate the stress, which could be a contributing factor for the mechanical enhancement.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Feasibility of Algal Biochar, a Byproduct of Biofuel Production, as a Supplemental Cementitious Material

Algal biochar, as the solid residue of biofuel production from algal biomass, is reported to explore disposition options, aiming to lessen the liability or obstacles to biofuel production processes. However, landfills and open combustion lead to adverse environmental impacts. One way to add value to such wastes is to use them as admixtures in cementitious construction materials. This study aims to investigate the feasibility of algae-derived biochar as supplementary cementitious materials (SCM) at different water contents and mixture ratios. Algal biochar-cement composites were prepared with different algal biochar content as well as different water-to-cement (w/c) ratios, and the surface area, morphology, elemental, and mineralogical composition were characterized. To compensate for the high-water absorption of algal biochar, a small concentration of a superplasticizer was used since higher w/c ratios negatively impact strength. The mechanical performance of algal biochar-cement composites is compared with control composites using commercial silica fume as a typical commercial SCM. The findings suggest that algal biochar is a promising candidate to replace commercial SCM, like silica fume, since algal biochar-cement composites can reach comparable compressive strength and Young’s modulus to commercial pozzolan-cement materials with the same w/c ratio, though at later curing times, 33 days. Although the tensile strength of algal biochar-cement composites is statistically similar at 7 days, it is significantly lower at later curing times, and further investigation is required to improve this property. Algal biochar-based cement binders showed comparable embodied carbon to silica fume-based cement binders based on a cradle-to-gate lifecycle analysis. However, the ability of algal biochar to absorb large volumes of CO 2 over short periods of time, as measured in this study, makes this novel SCM an excellent alternative to reduce the embodied carbon of concrete structures cradle-to-grave at 1/10 of the cost. In conclusion, valorization of algae-derived solid waste provides great potential to reduce embodied carbon and brings credit to biofuel production and concrete-based construction.

algae-derived↗
DOE OSTI2019

Strong and Tough Cellulose Nanofibrils Composite Films: Mechanism of Synergetic Effect of Hydrogen Bonds and Ionic Interactions

Cellulose nanofibrils (CNFs) have been exploited for different applications, such as nanocomposites, gas separation, flexible electronics, and fuel cells, due to their unique properties. To fulfill different demands regarding the utilization of CNFs, one critical step is to develop strong and tough CNF composites. In this study, facile synthesis of strong and tough nanocellulose films was demonstrated using a strategy that employs the synergetic effect of hydrogen bonds and ionic interactions in the films. With the addition of chitosan (CS) and copper ion (Cu 2+ ), the tensile strength and Young’s modulus of the newly developed film (CNF-CS-Cu) increased by 104% and 75%, respectively; more impressively, the toughness of CNF-CS-Cu improved by 560% compared to pure CNF. The hydrogen bonds and ionic interactions in the films were verified by attenuated total reflectance infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Results confirmed that the combination of hydrogen bonds and ionic interactions could yield much better performance in nanocellulose films. The development of facile, low-cost, scalable, and ecofriendly processing methods and formulations for the fabrication of strong nanocellulose-based films are essential and would significantly impact widespread utilization of such materials for a variety of applications requiring high performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

The Complicated Link Between Material Properties and Microfracture Density for an Underground Explosion in Granite

Geophysical techniques are often implemented as quick and inexpensive ways to locate and characterize fractures in the subsurface, which is important for a number of geoscience fields. Seismic velocities are the most widely used proxies for identification of fractures, but the correlation is not always well-defined. In this study we present material property data: unconfined compressive strength (UCS), bulk density (ρ), Young's modulus (E), Poisson's ratio (ν), P wave velocity (V p ), and S wave velocity (V s ), in conjunction with microfracture densities measured on samples of granite collected before and after underground chemical explosions. Results indicate the relationship between fractures and material properties is complex, even in this single-lithology environment. We interpret that this complexity arises from varying fracture mechanisms (e.g. dilation-inducing fractures vs compression-inducing fractures) in different parts of the core, due to differences in stress conditions. Additional complexity may result from chemical interactions between the fresh fractures and the fluids in the area. Water content appears to have a significant, if not dominant, role in the unconfined compressive strength (UCS) of the samples. We suggest caution when using elastic property measurements as a proxy for fracturing in areas of explosion-induced damage, or in other areas where a variety of mechanisms induce fracturing.

58 GEOSCIENCES↗
DOE OSTI2024

Experimental Observation of a New Attenuation Mechanism in hcp ‐Metals That May Operate in the Earth's Inner Core

Abstract Seismic observations show the Earth's inner core has significant and unexplained variation in seismic attenuation with position, depth and direction. Interpreting these observations is difficult without knowledge of the visco‐ or anelastic dissipation processes active in iron under inner core conditions. Here, a previously unconsidered attenuation mechanism is observed in zinc, a low pressure analog ofhcp‐iron, during small strain sinusoidal deformation experiments. The experiments were performed in a deformation‐DIA combined with X‐radiography, at seismic frequencies (∼0.003–0.1 Hz), high pressure and temperatures up to ∼80% of melting temperature. Significant dissipation (0.077 ≤ Q −1 (ω) ≤ 0.488) is observed along with frequency dependent softening of zinc's Young's modulus and an extremely small activation energy for creep (⩽7 kJ mol −1 ). In addition, during sinusoidal deformation the original microstructure is replaced by one with a reduced dislocation density and small, uniform, grain size. This combination of behavior collectively reflects a mode of deformation called “internal stress superplasticity”; this deformation mechanism is unique to anisotropic materials and activated by cyclic loading generating large internal stresses. Here we observe a new form of internal stress superplasticity, which we name as “elastic strain mismatch superplasticity.” In it the large stresses are caused by the compressional anisotropy. If this mechanism is also active inhcp‐iron and the Earth's inner‐core it will be a contributor to inner‐core observed seismic attenuation and constrain the maximum inner‐core grain‐size to ≲10 km.

Geochemistry & Geophysics↗
DOE OSTI2024

The Effect of Intracrystalline Water on the Mechanical Properties of Olivine at Room Temperature

Abstract The effect of small concentrations of intracrystalline water on the strength of olivine is significant at asthenospheric temperatures but is poorly constrained at lower temperatures applicable to the shallow lithosphere. We examined the effect of water on the yield stress of olivine during low‐temperature plasticity using room‐temperature Berkovich nanoindentation. The presence of water in olivine (1,600 ppm H/Si) does not affect hardness or yield stress relative to dry olivine (≤40 ppm H/Si) outside of uncertainty but may slightly reduce Young’s modulus. Differences between water‐bearing and dry crystals in similar orientations were minor compared to differences between dry crystals in different orientations. These observations suggest water content does not affect the strength of olivine at low homologous temperatures. Thus, intracrystalline water does not play a role in olivine deformation at these temperatures, implying that water does not lead to weakening in the coldest portions of the mantle.

58 GEOSCIENCES↗
DOE OSTI2016

Heterogeneous silicon mesostructures for lipid-supported bioelectric interfaces

Silicon-based materials have widespread application as biophysical tools and biomedical devices. Here we introduce a biocompatible and degradable mesostructured form of silicon with multi-scale structural and chemical heterogeneities. The material was synthesized using mesoporous silica as a template through a chemical vapour deposition process. It has an amorphous atomic structure, an ordered nanowire-based framework and random submicrometre voids, and shows an average Young’s modulus that is 2–3 orders of magnitude smaller than that of single-crystalline silicon. In addition, we used the heterogeneous silicon mesostructures to design a lipid-bilayer-supported bioelectric interface that is remotely controlled and temporally transient, and that permits non-genetic and subcellular optical modulation of the electrophysiology dynamics in single dorsal root ganglia neurons. Our findings suggest that the biomimetic expansion of silicon into heterogeneous and deformable forms can open up opportunities in extracellular biomaterial or bioelectric systems.

Jiang, Yuanwen↗
DOE OSTI2018

Designable and dynamic single-walled stiff nanotubes assembled from sequence-defined peptoids

Despite recent advances in assembly of organic nanotubes, conferral of sequence-defined engineering and dynamic response characteristics to the tubules remains a challenge. Here we report a new family of highly-designable and dynamic single-walled nanotubes assembled from sequence-defined peptoids through a unique “rolling-up and closure of nanosheet” mechanism. During the assembly process, amorphous spherical particles of amphiphilic peptoid oligomers (APOs) crystallized to form well-defined nanosheets which were then folded to form single-walled peptoid nanotubes (SW-PNTs). These SW-PNTs undergo a pH-triggered, reversible contraction-expansion motion. By varying the number of hydrophobic residues of APOs, we demonstrate the tuning of PNT wall thickness and diameter, and mechanical properties. AFM-based mechanical measurements indicate that PNTs are highly stiff (Young’s Modulus ~13-17 GPa), comparable to the stiffest known biological materials. We further demonstrate that the precise incorporation of functional groups within PNTs and the application of functional PNTs in water decontamination. We believe these SW-PNTs can provide a robust platform for development of biomimetic materials tailored to specific applications.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Microscopic mechanisms of deformation transfer in high dynamic range branched nanoparticle deformation sensors

Nanoscale stress sensing is of crucial importance to biomechanics and other fields. An ideal stress sensor would have a large dynamic range to function in a variety of materials spanning orders of magnitude of local stresses. In this, we show that tetrapod quantum dots (tQDs) exhibit excellent sensing versatility with stress-correlated signatures in a multitude of polymers. We further show that tQDs exhibit pressure coefficients, which increase with decreasing polymer stiffness, and vary >3 orders of magnitude. This high dynamic range allows tQDs to sense in matrices spanning >4 orders of magnitude in Young's modulus, ranging from compliant biological levels (~100 kPa) to stiffer structural polymers (~5 GPa). We use ligand exchange to tune filler-matrix interfaces, revealing that inverse sensor response scaling is maintained upon significant changes to polymer-tQD interface chemistry. We quantify and explore mechanisms of polymer-tQD strain transfer. An analytical model based on Mori-Tanaka theory presents agreement with observed trends.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Mechanically rigid supramolecular assemblies formed from an Fmoc-guanine conjugated peptide nucleic acid

The variety and complexity of DNA-based structures make them attractive candidates for nanotechnology, yet insufficient stability and mechanical rigidity, compared to polyamide-based molecules, limit their application. Here, we combine the advantages of polyamide materials and the structural patterns inspired by nucleic-acids to generate a mechanically rigid fluorenylmethyloxycarbonyl (Fmoc)-guanine peptide nucleic acid (PNA) conjugate with diverse morphology and photoluminescent properties. The assembly possesses a unique atomic structure, with each guanine head of one molecule hydrogen bonded to the Fmoc carbonyl tail of another molecule, generating a non-planar cyclic quartet arrangement. This structure exhibits an average stiffness of 69.6 ± 6.8 N m –1 and Young’s modulus of 17.8 ± 2.5 GPa, higher than any previously reported nucleic acid derived structure. This data suggests that the unique cation-free “basket” formed by the Fmoc-G-PNA conjugate can serve as an attractive component for the design of new materials based on PNA self-assembly for nanotechnology applications.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

High-performance 2D electronic devices enabled by strong and tough two-dimensional polymer with ultra-low dielectric constant

As the feature size of microelectronic circuits is scaling down to nanometer order, the increasing interconnect crosstalk, resistance-capacitance (RC) delay and power consumption can limit the chip performance and reliability. To address these challenges, new low-k dielectric (k < 2) materials need to be developed to replace current silicon dioxide (k = 3.9) or SiCOH, etc. However, existing low-k dielectric materials, such as organosilicate glass or polymeric dielectrics, suffer from poor thermal and mechanical properties. Two-dimensional polymers (2DPs) are considered promising low-k dielectric materials because of their good thermal and mechanical properties, high porosity and designability. Here, we report a chemical-vapor-deposition (CVD) method for growing fluoride rich 2DP-F films on arbitrary substrates. We show that the grown 2DP-F thin films exhibit ultra-low dielectric constant (in plane k = 1.85 and out-of-plane k = 1.82) and remarkable mechanical properties (Young’s modulus > 15 GPa). We also demonstrated the improved performance of monolayer MoS 2 field-effect-transistors when utilizing 2DP-F thin films as dielectric substrates.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Fundamental electronic structure and multiatomic bonding in 13 biocompatible high-entropy alloys

High-entropy alloys (HEAs) have attracted great attention due to their many unique properties and potential applications. The nature of interatomic interactions in this unique class of complex multicomponent alloys is not fully developed or understood. We report a theoretical modeling technique to enable in-depth analysis of their electronic structures and interatomic bonding, and predict HEA properties based on the use of the quantum mechanical metrics, the total bond order density (TBOD) and the partial bond order density (PBOD). Application to 13 biocompatible multicomponent HEAs yields many new and insightful results, including the inadequacy of using the valence electron count, quantification of large lattice distortion, validation of mechanical properties with experiment data, modeling porosity to reduce Young’s modulus. This work outlines a road map for the rational design of HEAs for biomedical applications.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Probing phonon focusing, thermomechanical behavior, and moiré patterns in van der Waals architectures using surface acoustic waves

Surface acoustic waves (SAWs) propagate along solid-air, solid-liquid, and solid-solid interfaces. Their characteristics depend on the elastic properties of the solid. Combining transmission electron microscopy (TEM) experiments with molecular dynamics (MD) simulations, we probe atomic environments around intrinsic defects that generate SAWs in vertically stacked two-dimensional (2D) bilayers of MoS 2 . Our joint experimental-simulation study provides insights into SAW-induced structural and dynamical changes and thermomechanical responses of MoS 2 bilayers. Using MD simulations, we compute mechanical properties from the SAW velocity and thermal conductivity from thermal diffusion of SAWs. The results for Young’s modulus and thermal conductivity of an MoS 2 monolayer are in good agreement with experiments. The presence of defects, such as nanopores which generate SAWs, reduces the thermal conductivity of 2D-MoS 2 by an order of magnitude. We also observe dramatic changes in moiré patterns, phonon focusing, and cuspidal structures on 2D-MoS 2 layers.

36 MATERIALS SCIENCE↗