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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 1,387 records · Page 77
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Ultrafast Laser Welding and Terahertz Time-domain Spectroscopy of Soda Lime Silicate Glass

Joining and welding techniques of similar and dissimilar materials have reached their limits due to the inflexibility of adapting dielectric materials, e.g., glasses and ceramics, reproducibility for transparent materials, and cycle process time. The ability to join pieces of glasses using laser irradiation allows rapid processing of vacuum insulating glass (VIG) for a widening range of commercial energy-efficient applications. We have used a 1064-nm laser wavelength with 15 picoseconds pulse width and a 155-kHz repetition rate to weld commercial plate glass pieces. The welded samples were characterized via x-ray fluorescence (XRF), time-of-flight secondary ion mass spectrometry (TOF–SIMS), polarimetry, and terahertz time-domain spectroscopy (THz-TDS) to determine the integrity of the weld and chemical changes in the welded areas. Our data shows no significant changes in glass chemistry and structure on average over nano- to micro-scales occurred from the welding process within the limits of the characterization tools. Our results demonstrate successful welding of glass plates without significant changes in the glass chemistry, structure, or properties in the laser-modified region or strains in the bulk glass.

Matthies, Kathleen [ORNL] (ORCID:0009000213135441)↗
DOE OSTI2020

Spectral Radiative Properties of Ceramic Particles for Concentrated Solar Thermal Energy Storage Applications

This work investigates the spectral radiative properties of ceramic particles using a monochromator and a Fourier-transform infrared spectrometer (FTIR) with integrating spheres at wavelengths from 0.38 μm to 15 μm. Particles are encased between two transparent windows to obtain the directional-hemispherical reflectance of the particle bed. Two types of commercially available particles with three different sizes are examined. Integration over the solar spectrum reveals that the solar absorptance of the particle beds is between 0.940 and 0.957. The total emittance at 1000 K is also estimated by assuming the spectral emittance is independent of temperature. The optical constants of particles are modeled with effective medium approaches, considering the optical properties of individual constituent materials. The absorptance of the particle is estimated using the effective optical constants and compared with that of the particle bed from the measurement. Finally, this work facilitates the characterization of radiative properties of particles with a windowed method and provides a modeling scheme for approximating the radiative properties of composite ceramic materials.

14 SOLAR ENERGY↗
DOE OSTI2022

Portable C++ Code that can Look and Feel Like Fortran Code with Yet Another Kernel Launcher (YAKL)

This paper introduces the Yet Another Kernel Launcher (YAKL) C++ portability library, which strives to enable user-level code with the look and feel of Fortran code. The intended audience includes both C++ developers and Fortran developers unfamiliar with C++. The C++ portability approach is briefly explained, YAKL’s main features are described, and code examples are given that demonstrate YAKL’s usage. YAKL fills a niche capability important particularly to scientific applications seeking to port Fortran code quickly to a portable C++ library. YAKL places heavy emphasis on simplicity, readability, and productivity with performance mainly emphasizing Graphics Processing Units (GPUs). Central to YAKL’s ability to allow Fortran-like user-level code are three features: (1) a multi-dimensional Array class that allows Fortran behavior; (2) a limited library of Fortran intrinsic functions; and (3) an efficient pool allocator that transparently enables cheap frequent allocations and deallocations of YAKL Arrays. While YAKL allows Fortran-style code, it also allows Arrays that exhibit C-like behavior as well, including row-major index ordering and lower bounds of “0”. YAKL currently supports CPUs, CPU threading, and Nvidia, AMD, and Intel GPUs.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

Influence of γ-Irradiation on the Optical Properties of the Polyimide–YBa{sub 2}Cu{sub 3}O{sub 6.7} System

Influence of γ-irradiation on the optical properties of a polyimide film and its polymer compositions with fillers of a dispersed powder of a high-temperature superconductor ҮBa{sub 2}Cu{sub 3}O{sub 6.7} (YBaCuO) with concentrations of 0.05, 0.10, and 0.50 wt.% was studied. It was established that γ-irradiation with a dose up to 600 kGy does not affect the transparency of polyimide films in the visible region of the spectrum. However, at irradiation doses of 250 and 600 kGy, a weakly expressed fine structure appears in the spectra of polyimide films in the range of 220–300 nm due to the contribution of the resulting diene structures to the optical transmission and the increased content of oxygen atoms. The YBaCuO filler and γ-irradiation cause the polyimide transition from the amorphous state to the crystalline state, which is manifested in a sharp change in the spectrum in the range of ~2.3–3.9 eV. A significant increase in the extinction coefficient was found in the composite containing 0.50 wt.% of the filler that is associated with an increase in the radius of action of structurally active fillers on the macromolecules of the matrix.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Optical Properties of Amorphous Perfluorinated Polymers in the Terahertz Range

Novel amorphous perfluorinated polymers are synthesized and characterized using terahertz (THz) and x-ray spectra. The polymerization of such polymers in which all H atoms are replaced by F is examined. Their optical properties in the THz range show a record low index of refraction for solids in this range. The minimal possible index of refraction for such polymers is estimated. These materials are demonstrated to be highly transparent. The position of a weak absorption maximum in the range 1–2 THz is compared with the characteristic distance between the polymer structural elements that is obtained from an x-ray diffraction analysis of these materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Nanosecond Surface Microdischarges in Multilayer Structures

Multilayer structures in which nanosecond surface microdischarges are generated have been developed, fabricated, and investigated. In these structures, layers are made in the form of thin transparent films, and a plasma discharge channel is formed in thin spacings between the layers. Passage of the discharge channel from one layer into the neighboring layer is implemented via pre-fabricated microholes. Images of microdischarges were obtained which confirmed that their plasma channels are formed according to the route assigned by the holes. The route may follow a fairly complex scheme and have self-intersection points and portions in which the electrons are bound to move in opposition to the electric field. In studying the shape of channels in multilayer strictures, the authors have found a new physical effect which lies in the azimuthal self-orientation of the discharge channel as it passes from one microhole to another.

42 ENGINEERING↗
DOE OSTI2018

Two Photon Spectroscopy Can Serve as a Marker of Protein Denaturation Pathway

Rhodamine group of molecules are widely used dyes for imaging of biological molecules. Application of these dyes however includes a limitation that these molecules absorb in the visible range of the spectrum, which does not fall in the ‘biologically transparent window’ (BTW). Two photon absorption (TPA) process could come up with an alternate solution to this as these dyes could be excited in the near infrared (NIR) window to extract similar information. To validate this we have investigated TPA cross section (TPACS, σ{sub 2}) of two rhodamine dyes, namely Rhodamine 6G (R6G), Rhodamine B (RhB), site selectively bound with a model protein, bovine serum albumin (BSA), by exciting at 800 nm. Two photon spectroscopy and imaging confirms the binding of the dye to the protein. The decreases in TPACS with increasing temperature at a fixed BSA concentration excellently follows the temperature induced structural transition of BSA as the protein transforms from a molten globule to unfolded conformation beyond 60 °C, which has previously been established through circular dichroism (CD) measurements. The thus established resemblance in TPACS and CD measurement trends thus strongly affirms the suitability of TPA process in protein imaging and as an alternative marker to tracking its conformational transformations using NIR radiation.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2017

Scatter Signal Elimination by Localized Primary Modulation in Industrial Computed Radiography

In industrial computed radiography, same as the other projection imaging systems, quantitative integrated information of total beam path including the object is carried by primary part of the beam. It is well known that the accuracy of the image useful data carried by the primary part degrades by scattered part of the beam. In order to have the beam path quantitative information accurately, it is essential to obtain the primary part of the total signal purely. In current study, a practical approach using localized primary modulation has been proposed to extract the primary signal. A semi-transparent beam attenuation grid was used as the beam intensity modulator. Efficiency and accuracy of the approach was practically validated through thickness measurement of metallic planar steps as an illustrative example. Simplified practical implementation and availability of the required accessories are some of advantages of the proposed approach. The results are indicative of the fact that this approach can also be applied as a new technique in thickness measurement, yielding a noticeable accuracy improvement in the most radiography methods. A procedure is included to explain the approach implementation for thickness measurement in computed radiography systems. The procedure overcomes some practical limitations and difficulties of the approach adaptation for computed radiography.

42 ENGINEERING↗
DOE OSTI2017

Study of Optical Properties of Polymeric Materials Subjected to Degradation

Results of a study on polyethylene, polyvinyl chloride, latex and polypropylene films by photocolorimetry are described. The polymeric films were subjected to destructive environmental factors as ozone, ultra-violet irradiation and γ-radiation. It is shown that these factors can lead to a reduction or an increase of transparency. This fact is due to the mechanisms of crosslinking, crystallization and destruction of macromolecules. Correlation between the photocolorimetry data and distributions of relaxation times of a nuclear magnetic resonance of protons in different sites of the polymeric network received earlier is established.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Antibacterial and Structural Properties and Printability of Starch/Clay/Polyethylene Composite Films

A composite of thermoplastic starch (TPS), low-density polyethylene (LDPE) and citric acid-modified montmorillonite (CMMT) was prepared in a twin screw extruder for packaging film application. Starch was first converted to the thermoplastic state by using sorbitol and water. Composite films were produced on a chill roll system and then were modified for printability by grafting of acrylonitrile onto the starch backbone. Antimicrobial property and printability of the films were studied from which the sample with the highest antimicrobial property and the best printability was selected. This optimal sample was then characterized by Fourier transform infrared, thermal gravimetric analysis, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. The composite film showed a matrix/dispersed morphology in which LDPE formed a continuous phase and TPS/CMMT nanocomposite particles appeared as dispersed phase. Biodegradability, water absorption, oxygen permeability, tensile strength and transparency of optimal film were also studied. The results indicated very good properties of the produced composite film for packaging application. Graphical Abstract: .

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Nanocomposites of Waterborne Polyurethane Reinforced with Cellulose Nanocrystals from Sisal Fibres

Cellulose nanocrystals (CNC) were isolated from sisal fibres and were incorporated in the form of an aqueous suspension to a waterborne polyurethane (WBPU) synthesized from components derived from natural sources using an aliphatic diisocyanate. Transparent nanocomposite films with different CNC contents were prepared using a casting method. The morphology, thermal behaviour and mechanical properties of the nanocomposite films were characterized. Homogeneous distribution of CNC in the WBPU, even at high CNC contents was observed, resulting in an increase of 100% in modulus for systems with 5 and 10 wt% of CNC, with high elongations around 650%.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A Novel Packaging Film from Cassava Starch and Natural Rubber

Currently, there is an environmental pollution problem generated in part by packaging materials produced from non-biodegradable synthetic polymers made from petroleum. However, these can be replaced with biodegradable materials made from cassava starch (CS) and natural rubber (NR). In the work described, a novel biopolymer film was obtained from the CS and NR using glycerol (GE) as a plasticizer in a water-based system. The physical properties of an 95/5 CS/NR blend films with the addition of NR and with varying GE contents were studied based on their swelling ratio, moisture content, moisture absorption, mechanical properties and biodegradability in soil. The results showed that the moisture content and moisture absorption tended to be directly proportional to the GE content, while the moisture content and moisture absorption of the sample decreased as a function of the NR content. The swelling ratio of the 95/5 CS/NR blend slightly decreased as a function of the NR and GE content. Surprisingly, the best swelling ratio of 350% was found at 10% NR. The elongation at break of the CS/NR blend was improved by the addition of GE. The contact angle of the 95/5 CS/NR blend decreased as a function of the GE. With increased NR in the composite, an increasing, trend in the contact angle was found. Further, the 95/5 CS/NR blend exhibited good transparency when it was applied as a coating to delay the ripening of bananas, the results were positive. Moreover, the film showed decomposition well in natural soil.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

RF Plasma Polymerization of Orange Oil and Characterization of the Polymer Thin Films

The present study describes an environmentally friendly approach to fabricate hydrocarbon-rich polymer thin films from a bio-renewable precursor, orange oil, cold extracted from orange peels using radio frequency plasma polymerization. The polymer thin films fabricated at different RF power level (10–75 W) were characterized with variable angle spectroscopic ellipsometry, UV–visible spectroscopy, Fourier transform infrared spectroscopy and atomic force microscopy. Optical characterization showed that independent of deposition power films exhibited good transparency (~ 90%) in the visible region and a refractive index of 1.55 at 500 nm. The optical band gap measured around 3.60 eV and falls within the insulating region. The atomic force microscopic images revealed that the surface is pinhole-free in nature and smooth at nanoscale, with average surface roughness dependent on the deposition power. Film hardness increased from 0.50 to 0.78 GPa as applied power increased from 10 to 75 W.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Properties of Poly(Vinyl Alcohol)/Chitosan Nanocomposite Films Reinforced with Oil Palm Empty Fruit Bunch Amorphous Lignocellulose Nanofibers

The objective of this study was to investigate the properties of poly(vinyl alcohol)/chitosan nanocomposite films reinforced with different concentration of amorphous LCNFs. The properties analyzed were morphological, physical, chemical, thermal, biological, and mechanical characteristics. Oil palm empty fruit bunch LCNFs obtained from multi-mechanical stages were more dominated by amorphous region than crystalline part. Varied film thickness, swelling degree, and transparency of PVA/chitosan nanocomposite films reinforced with amorphous part were produced. Aggregated LCNFs, which reinforced PVA/chitosan polymer blends, resulted in irregular, rough, and uneven external surfaces as well as protrusions. Based on XRD analysis, there were two or three imperative peaks that indicated the presence of crystalline states. The increase in LCNFs concentration above 0.5% to PVA/chitosan polymer blends led to the decrease in crystallinity index of the films. A noticeable alteration of FTIR spectra, which included wavenumber and intensity, was obviously observed along with the inclusion of amorphous LCNFs. That indicated that a good miscibility between amorphous LCNFs and PVA/chitosan polymer blend generated chemical interaction of those polymers during physical blending. Reinforcement of PVA/chitosan polymer blends with amorphous LCNFs influenced the changes of T{sub g} (glass transition temperature), T{sub m} (melting point temperature), and T{sub max} (maximum degradation temperature). Three thermal phases of PVA/chitosan/LCNFs nanocomposite films were also observed, including absorbed moisture evaporation, PVA and chitosan polymer backbone structural degradation and LCNFs pyrolysis, and by-products degradation of these polymers. The addition of LCNFs 0.5% had the highest tensile strength and the addition of LCNFs above 0.5% decreased the strength. The incorporation of OPEFB LCNFs did not show anti-microbial and anti-fungal properties of the films. The addition of amorphous LCNFs 0.5% into PVA/chitosan polymer blends resulted in regular and smooth external surfaces, enhanced tensile strength, increased crystallinity index, and enhanced thermal stability of the films.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Photo-Stabilisation and UV Blocking Efficacy of Coated Macro and Nano-Rutile Titanium Dioxide Particles in Paints and Coatings

Surface treated macro and nanoparticle TiO{sub 2} samples have been prepared, characterised and their efficiency as UV blockers evaluated in clear coatings and paints. The particle size of the ‘base’ TiO{sub 2} has been optimised to block UV radiation and the surface treatment developed to deactivate the photocatalytic activity of the surface of the TiO{sub 2} particles. The resultant UV blockers have been evaluated in both solvent and water-based clear coatings. Nanoparticle TiO{sub 2} has been prepared from ‘seed’ and the particle size was controlled by calcination. It was found that the choice of particle size is a compromise between UVA absorption, UVB absorption, visible transmission and photoactivity. It has been demonstrated that TiO{sub 2} with a crystallite size of 25 nm yields a product with the optimum properties. A range of dispersants was successfully used to disperse and mill the TiO{sub 2}. Both organic and inorganic dispersants were used; 2-amino-2-methyl-1-propanol and 1-amino-2-propanol (MIPA) and P{sub 2}O{sub 5} and Na{sub 2}SiO{sub 3} respectively. The surface of the nano-TiO{sub 2} was coated with mixed oxides of silicon, aluminium, zirconium and phosphorous. Addition of the resultant coated nano-rutiles to an Isocyanate Acrylic clear coating prolonged the lifetime of that coating compared to the blank. Generally, a surface treatment based on SiO{sub 2}, Al{sub 2}O{sub 3} and P{sub 2}O{sub 5} was more successful than one based on ZrO{sub 2}, Al{sub 2}O{sub 3} and P{sub 2}O{sub 5}. Higher addition levels of the surface treatment were beneficial for protecting the polymeric coating. The UV blocker products were also evaluated in a water-based acrylic, first a water-based dispersion of the UV blocker was prepared before addition to the acrylic. The dispersions and resultant acrylic thin films were evaluated using UV/Vis spectroscopy and durability assessed. The ratio of absorbance at 300:500 nm for the water-based dispersion was shown to be a good predictor of both the transparency of the resultant acrylic thin film and the durability of that film, in terms of weight loss. Macro grade titanium dioxide pigments were also prepared and coated with treatments of silica, alumina and siloxane and their photo-stabilising activity in alkyd paint film assessed and found to be directly related to the electron–hole pair mobility and trapping as determined by micro-wave spectroscopy.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Nanocomposites Based on Poly(lactic acid) and Bacterial Cellulose Acetylated by an α-Hydroxyacid Catalyzed Route

Poly(lactic acid) (PLA) nanocomposite films reinforced with acetylated bacterial cellulose nanoribbons were prepared by solvent casting. Acetylation of bacterial cellulose (BC) was performed by an innovative and sustainable direct solvent-free route catalyzed by citric acid. The effect of derivatization and its extent on the morphological, optical, thermal and mechanical properties of the nanocomposites was analyzed. Data collected from the above studies showed that acetylation of BC nanoribbons clearly improved the nanofibers dispersion in the PLA matrix with respect to unmodified BC, which in turn resulted in increased transparency and mechanical properties of the nanocomposites produced.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Effect of Natural Glyceryl Tributyrate as Plasticizer and Compatibilizer on the Performance of Bio-Based Polylactic Acid/poly(3-hydroxybutyrate) Blends

Bio-based poly(lactic acid)/poly(3-hydroxybutyrate) (PLA/PHB) films were melt-blended with a natural hydrophobic plasticizer (glyceryl tributyrate, TB) at three different concentrations (10, 15 and 20% by weight per 100 parts of the blends) to study the effect of TB on the final properties of the materials. The pursued aim was to obtain a material with potential use in the packaging industry. Two different PLA/PHB ratios were used, 70/30 and 60/40, respectively. A full characterization of the developed blends was carried out, including the morphological, thermal, mechanical and barrier properties. The thermal test revealed the immiscibility between PLA and PHB by showing two glass transition temperatures for the blends and biphasic melt. Mechanical tests showed the increased in the elongation at break as the plasticizer content in films increased. The incorporation of PHB crystals in the PLA matrix displayed an improvement in the water barrier properties of materials. Finally, formulations PLA/PHB-TB with 15 wt% of plasticizer presented the best combination of properties suitable for the intended use in films manufacturing, showing toughness and ductility, good water barrier properties and transparency with slightly amber color.

36 MATERIALS SCIENCE↗
DOE OSTI2019

A Review on Material and Antimicrobial Properties of Soy Protein Isolate Film

In twenty first century, there is an increasing demand for packed food which requires packaging films. At present, these packaging films are processed from synthetic polymers such as polyethylene, polypropylene and many other synthetic polymers. But we need to start using soy protein as sustainable antimicrobial film that can be used for packaging purposes. There is abundance and high availability of soy protein isolate (SPI) as by-product from industries, such as food processing or biodiesel production. Soy based films from renewable resources can offer a more suitable alternative to films fabricated from synthetic materials. Soy based films in presence of additives such as acidic compounds, nanoparticles and natural compounds have good mechanical properties and are transparent in nature. In addition, soy based film in presence of 2,2-diphenyl-2-hydroxyethanoic acid and copper phosphate can give lotus-like structure as evidenced from morphological studies. Also the manufacturing process (solution casting and compression molding) of SPI film in the presence or absence of additives is very easy and commercially feasible. It is worth noting that SPI films can be produced at laboratory scale by both casting and compression molding methods. In this review paper, we have focused on the material properties as well as antimicrobial properties of SPI based films in the presence of natural and synthetic additives as reported in the last 20 years.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗