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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

2-Aminoanthracene Crystallization in Its Compatible Polystyrene Block: RAFT Synthesis and Enhanced Charge Retention in Pentacene Transistor Gate Dielectrics

We synthesized polystyrene-block-polyanthrylaminomethylstyrene (PS-b-PAAS) via RAFT reaction and side chain modification where the PAAS block is 50%. By blending 2-aminoanthracene (2AA) with PS-b-PAAS, the co-aggregation behavior of the PAAS block and 2AA within the thin film was observed by optical microscopy (OM) and x-ray diffraction. At 5 and 10 wt% of 2AA within the thin film, OM results showed a clear morphological difference between PS matrix and PS-b-PAAS matrix. Differences in the 2AA excited state lifetime in these matrices were also established using transient absorption spectroscopy (TAS). Blends were used as gate dielectrics in pentacene transistors. We compared characteristic voltage (Vc, an indicator of threshold voltage) before and after charging of PS-b-PAAS blended with unsubstituted PS and both polymers individually blended with 2AA. For blended PS-b-PAAS and PS, as the concentration of PS-b-PAAS increases, the decreased Vc especially with negative charging of the pentacene indicated a larger concentration of charge carriers induced by the dielectric film. The charging experiments also revealed that the unique structure formed by the 2AA/PS-b-PAAS blend significantly affected the charge storage capability of the organic field-effect transistors (OFET). Furthermore, this work demonstrates the novel co-aggregation structure in the dielectrics, and furthermore its impact on charge storage capability in pentacene OFETs.

36 MATERIALS SCIENCE↗
NASA NTRS1988

Effects Of Radiation On Insulators

Report presents data on responses of electrically insulating thermosetting and thermoplastic polymers to radiation. Lowest-threshold-dose (LTD) levels and 25-percent-change levels presented for such properties as tensile strength and electrical resistivity. Data on radiation-induced outgassing also given.

Bouquet, Frank L.↗
NASA NTRS1993

Reversible non-volatile switch based on a TCNQ charge transfer complex

A solid-state synaptic memory matrix (10) having switchable weakly conductive connections at each node (24) whose resistances can be selectably increased or decreased over several orders of magnitude by control signals of opposite polarity, and which will remain stable after the signals are removed, comprises an insulated substrate (16), a set of electrical conductors (14) upon which is deposited a layer (18) of an organic conducting polymer, which changes from an insulator to a conductor upon the transfer of electrons, such as polymerized pyrrole doped with 7,7,8,8-tetracyanoquinodimethane (TCNQ), covered by a second set of conductors (20) laid at right angles to the first.

Nagasubramanian, Ganesan↗
NASA NTRS1995

Radiation Effects in Photonic Modulator Structures

%T Radiation Effects in Photonic Modulator Structures%A Charles Barnes%A Roger Greenwell%J SPIE, Photonics for Space Environments%C Orlando, Florida, U.S.A.%D April 18-20, 1995%K Radiation%K Photonic Modulator Structures%U http://techreports.jpl.nasa.gov/1995/95-1057.pdfA review is given of the effects of radiation on various photonic modulator materials and devices including polymer-based structures, insulator-based devices, semiconductor-based devices and spatial light modulators. We conclude by providing recommendations for further work in the area of radiation effects in photonic modulators.!

Photonic↗
NASA NTRS1988

SRM (Solid Rocket Motor) propellant and polymer materials structural modeling

The following investigation reviews and evaluates the use of stress relaxation test data for the structural analysis of Solid Rocket Motor (SRM) propellants and other polymer materials used for liners, insulators, inhibitors, and seals. The stress relaxation data is examined and a new mathematical structural model is proposed. This model has potentially wide application to structural analysis of polymer materials and other materials generally characterized as being made of viscoelastic materials. A dynamic modulus is derived from the new model for stress relaxation modulus and is compared to the old viscoelastic model and experimental data.

Moore, Carleton J.↗
DOE OSTI2022

Thermal conductivity of multilayer polymer-nanocomposite thin films

The development of electrical insulators that are thermally conducting is critical for thermal management applications in many advanced electronics and electrical devices. Here, we synthesized polymer nanocomposite (PNC) films composed of polymers [polyethylenimine, poly(vinylamine), poly(acrylic acid), and poly(ethylene oxide)] and dielectric fillers (montmorillonite clay and hexagonal boron nitride) by layer-by-layer technique. The cross-plane thermal conductivity (k⊥) of the film was measured by the 3ω method. The effect of various factors such as film growth, filler type, filler volume fraction, polymer chemical structures, and temperature on the thermal conductivity is reported. The k⊥ of PNCs with thickness from 37 nm to 1.34 μm was found to be in the range of 0.11 to 0.21 ± 0.02 W m−1 K−1. The k⊥ values were found to be lower than the constituent polymer matrix. The experimental result is compared with existing theoretical models of nanocomposite systems to get insight into heat transfer behavior in such layered films composed of dielectrics and polymers.

Physics↗
DOE OSTI2022

The effect of barrier films and exposure on the aging of vacuum insulation panels with fumed silica cores

Vacuum insulation panels have very low thermal conductivities compared to conventional insulation materials. The reduction of the core pressure significantly lowers gas phase conduction and overall thermal conductivity. As a consequence, increases in gas pressure can significantly increase thermal conductivity of the VIP. In addition, the thermal conductivity of the core is sensitive to moisture content. For vacuum insulation panels with fumed silica cores, work shows that the measured thermal conductivity increases by 0.5 x 10-3 W/mK per mass percent increase in water content [1]. This is significant since the thermal conductivity of vacuum insulation panels with fumed silica cores is in the range of 0.004 W/mK. This work investigates the long-term behavior of vacuum insulation panels comprised of fumed silica cores with polymer (ethylene vinyl alcohol) and metalized (aluminized) barrier films exposed to different exposure conditions: ambient conditions; exterior conditions in a mixed humid climate; and 24oC and 80 percent relative humidity. Results show that the increase in thermal conductivity is more pronounced for vacuum insulation panels made using polymer barrier films compared to the same panel protected by a metalized film. The increase is more pronounced when exposed to high relative humidity, 80 percent. After almost two years exposure, the decrease in thermal conductivity for vacuum insulation panels protected by a metalized barrier films are between 4 and 11 percent depending on exposure condition. The smallest decrease is for ambient conditions where the largest decrease is for exposure to 80 percent relative humidity. Similar behavior was observed for panels protected using polymer films, except the decrease in thermal conductivity was significantly higher, between approximately 20 and 60 percent, in the same order as for panels protected by metalized films. Measurements are ongoing with an attempt to develop a better relationship between these types of tests and vacuum insulation panel service life.

Aldykiewicz Jr, Antonio↗
NASA NTRS2010

Foam/aerogel composite materials for thermal and acoustic insulation and cryogen storage

The invention involves composite materials containing a polymer foam and an aerogel. The composite materials have improved thermal insulation ability, good acoustic insulation, and excellent physical mechanical properties. The composite materials can be used, for instance, for heat and acoustic insulation on aircraft, spacecraft, and maritime ships in place of currently used foam panels and other foam products. The materials of the invention can also be used in building construction with their combination of light weight, strength, elasticity, ability to be formed into desired shapes, and superior thermal and acoustic insulation power. The materials have also been found to have utility for storage of cryogens. A cryogenic liquid or gas, such as N.sub.2 or H.sub.2, adsorbs to the surfaces in aerogel particles. Thus, another embodiment of the invention provides a storage vessel for a cryogen.

Williams, Martha K.↗
NASA NTRS2011

Foam/Aerogel Composite Materials for Thermal and Acoustic Insulation and Cryogen Storage

The invention involves composite materials containing a polymer foam and an aerogel. The composite materials have improved thermal insulation ability, good acoustic insulation, and excellent physical mechanical properties. The composite materials can be used, for instance, for heat and acoustic insulation on aircraft, spacecraft, and maritime ships in place of currently used foam panels and other foam products. The materials of the invention can also be used in building construction with their combination of light weight, strength, elasticity, ability to be formed into desired shapes, and superior thermal and acoustic insulation power. The materials have also been found to have utility for storage of cryogens. A cryogenic liquid or gas, such as N.sub.2 or H.sub.2, adsorbs to the surfaces in aerogel particles. Thus, another embodiment of the invention provides a storage vessel for a cryogen.

Williams, Martha K.↗
NASA NTRS2007

Process for self-repair of insulation material

A self-healing system for an insulation material initiates a self-repair process by rupturing a plurality of microcapsules disposed on the insulation material. When the plurality of microcapsules are ruptured reactants within the plurality of microcapsules react to form a replacement polymer in a break of the insulation material. This self-healing system has the ability to repair multiple breaks in a length of insulation material without exhausting the repair properties of the material.

Parrish, Clyde F.↗
NASA NTRS2007

Process for Self-Repair of Insulation Material

A self-healing system for an insulation material initiates a self-repair process by rupturing a plurality of microcapsules disposed on the insulation material. When the plurality of microcapsules are ruptured reactants witlun the plurality of microcapsules react to form a replacement polymer in a break of the insulation material. This self-healing system has the ability to repair multiple breaks in a length of insulation material without exhausting the repair properties of the material.

Parrish, Clyde F.↗
NASA NTRS2012

Self-Healing Wire Insulation

A self-healing system for an insulation material initiates a self-repair process by rupturing a plurality of microcapsules disposed on the insulation material. When the plurality of microcapsules are ruptured, reactants within the plurality of microcapsules react to form a replacement polymer in a break of the insulation material. This self-healing system has the ability to repair multiple breaks in a length of insulation material without exhausting the repair properties of the material.

Parrish, Clyde F.↗
NASA NTRS1990

A brief survey of radiation effects on polymer dielectrics

Future space power needs are extrapolated to be at least three to four orders of magnitude more than is currently available. This long-term reliable power will be required on missions such as the Space Station, Pathfinder, Space Plane, and high-powered satellites, and for defense. Electrical insulation and dielectrics are the key electrical materials needed to support these power systems, where a single-point system failure could prove catastrophic or even fatal for the whole mission. Therefore, the impact of radiation, an environmental stress, on the properties and performance of insulation and dielectrics must be understood. The influence of radiation on polymer dielectrics, the insulating materials most commonly used for power transmission and storage, is reviewed. The effects of the type of radiation, dose, rate, and total exposure on the key electrical, mechanical, and physical properties of polymer dielectrics are described and explained.

Laghari, Javaid R.↗
NASA NTRS2017

Polymer Nanofiber Based Reversible Nano-Switch/Sensor Diode (Nanosssd) Device

A nanostructure device is provided and performs dual functions as a nano-switching/sensing device. The nanostructure device includes a doped semiconducting substrate, an insulating layer disposed on the doped semiconducting substrate, an electrode formed on the insulating layer, and at least one polymer nanofiber deposited on the electrode. The at least one polymer nanofiber provides an electrical connection between the electrode and the substrate and is the electroactive element in the device.

Miranda, Felix A.↗
NASA NTRS1988

Safety research of insulating materials of cable for nuclear power generating station

The polymers PE, EPR, PVC, Neoprene, CSP, CLPE, EP and other similar substances are frequently used as insulation and protective covering for cables used in nuclear power generating stations. In order to test these materials for flame retardation, environmental resistance, and cable specifications, they were given the cable normal test, flame test, chemical tests, and subjected to design analysis and loss of coolant accident tests. Material was collected on spark tests and actual experience standards were established through these contributions and technology was accumulated.

Lee, C. K.↗
NASA NTRS2018

Polymer Nanofiber Based Reversible Nano-Switch/Sensor Schottky Diode (Nanosssd) Device

A nanostructure device is provided and performs dual functions as a nano-switching/sensing device. The nanostructure device includes a doped semiconducting substrate, an insulating layer disposed on the doped semiconducting substrate, an electrode formed on the insulating layer, and at least one polymer nanofiber deposited on the electrode. The at least one polymer nanofiber provides an electrical connection between the electrode and the substrate and is the electroactive element in the device.

Miranda, Felix A.↗
DOE OSTI2020

Size Effects in the Thermal Conductivity of Amorphous Polymers

Manipulating thermal conductivity through nanoengineering is of critical importance to advance technologies, such as soft robotics, artificial skin, wearable electronics, batteries, thermal insulation, and thermoelectrics. Here, by examining amorphous polymers, including polystyrene, polypropylene, polyethylene, and ethylene vinyl alcohol, using molecular dynamics simulations, we find that the thermal conductivities of amorphous polymers can be reduced below their amorphous limit by size effects. Size-dependent thermal transport in amorphous materials is decomposed into crystalline, crystalline-to-amorphous, and amorphous regimes. In the amorphous regime, the mean free path of propagating heat carriers can range from tens of nanometers to more than 100 nm, contributing 16%–36% of the total thermal conductivity. A two-channel model that combines no size effect (i.e., difusons and locons) and size effect (i.e., propagons) is proposed to account for size-dependent thermal conductivity. We also find that the presence of charged molecules in polymers can significantly affect the thermal conductivity and its size effects due to electrostatic interactions. Overall, this work provides insights into the thermal conductivity of amorphous polymers that will have a broad impact on the nano- and chemical engineering of polymers for various energy-related applications.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Application of Poly(ether sulfone)‐Based Membranes in Clean Energy Technology

Abstract Poly(ether sulfone) (PES) is a kind of polymer materials with excellent electrical insulation and acid/alkali stability. PES can be operated at high temperature continuously for a long time and still maintain excellent property stability in the environments with rapidly changed temperature, namely, great thermostability. Moreover, PES has low molding shrinkage, good dimensional stability and excellent film‐forming characteristics. Compared with inorganic membranes, PES‐based membranes have lower cost, which have received more attention and wide recognition in the field of clean energy technologies in recent years, such as flow batteries, fuel cells, water treatment, and gas separation. Therefore, this review summarizes the research status and prospect of the utilization of PES‐based membranes in clean energy fields, in order to further promote their development and application.

Chemistry↗