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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Adhesive evaluation of thin films of LARC-TPI and LARC-TPI with 5 mol % ODA

A commercially available LARC-TPI film and an experimentally prepared film of LARC-TPI with 5 mol % of 4,4'-oxydianiline (ODA), designated as LARC-TPI/ODA in the report, supplied by Mitsui Toatsu Chemicals, Incorporated (MTCI), Japan, were evaluated as thermoplastic adhesive films for bonding Ti-6Al-4V. The LARC-TPI/ODA had been shown by MTCI to possess more flow than thermoplastic LARC-TPI and was, therefore, evaluated and compared to the LARC-TPI. Lap shear strength was used to evaluate the materials as adhesives. They were characterized after fracture by determining the glass transition temperature, Tg. The mode of failure was also reported. Thermal exposure at 204C for 500 and 1000 hrs and a 72-hour water-boil were conducted on lap shear specimens prepared with the two adhesive films. Lap shear tests were conducted at RT, 177C, 204C, and 232C before and after exposures.

Progar, D. J.↗
NASA NTRS1990

Biaxial extrusion of polyimide LARC-TPI and LARC-TPI blends

Biaxial films of polyimide LARC-TPI and LARC-TPI/liquid crystal polymer Xydar were extruded directly from the melt for the first time via an innovative extrusion technique. Three types of films, neat LARC-TPI, LARC-TPI/10 wt pct and 30 wt pct blends were processed as a part of this NASA-funded program. Processability was greatly enhanced by incorporating Xydar. The coefficient of thermal expansion was reduced from 34 ppm/C for the neat LARC-TPI to 15 ppm/C for the 10 wt pct Xydar blend and ultimately down to 1 to 3 ppm/C for the 30 wt pct blend films in the direction of extrusion. The maximum improvement in stiffness was realized by incorporating 10 wt pct Xydar (2.8 GPa up to 4.9 GPa). Tensile strength, however, experienced a drop as a result of Xydar addition, probably caused by inefficient mixing of the two phases.

Haghighat, R. Ross↗
NASA NTRS1985

Adhesive evaluation of LARC-TPI and a water-soluble version of LARC-TPI

The results of a study to evaluate two Langley Research Center thermoplastic polimide (TPI) materials, identified as TPI/MTC for the material from Mitsui Toatsu Chemicals Inc. and TPI/H2O for the material from United Technologies Research Center, as high temperature thermoplastic adhesives and primers for bonding titanium (6AL-4V) adherends are discussed. A limited characterization of the materials was performed using a Diffuse Reflectance-Fourier Transform Infrared Spectroscopy (DR-FTIR) technique. Thermomechanical Analysis (TMA) and torsional braid techniques were used to determine glass transition temperature. The adhesive's strength, as determined by simple lap shear tests, as used to evaluate the effects of long term thermal exposure (up to 1000 hrs) at 204 deg C and a 72-hour water-boil.

Progar, D. J.↗
NASA NTRS1986

Adhesive evaluation of LARC-TPI and a water-soluble version of LARC-TPI

The results of a study to evaluate two Langley Research Center thermoplastic polimide (TPI) materials, identified as TPI/MTC for the material from Mitsui Toatsu Chemicals Inc. and TPI/H2O for the material from United Technologies Research Center, as high temperature thermoplastic adhesives and primers for bonding titanium (6AL-4V) adherends are discussed. A limited characterization of the materials was performed using a Diffuse Reflectance-Fourier Transform Infrared Spectroscopy (DR-FTIR) technique. Thermomechanical Analysis (TMA) and torsional braid techniques were used to determine glass transition temperature. The adhesive's strength, as determined by simple lap shear tests, was used to evaluate the effects of long term thermal exposure (up to 1000 hrs) at 204 deg C and a 72-hour water-boil.

Progar, D. J.↗
NASA NTRS1990

Improved melt flow and physical properties of Mitsui Toatsu's LARC-TPI 1500 series polyimide

The basic thermal properties and melt behavior of an improved form of LARC-TPI polyimide, LARC-TPI 1500, are investigated and compared with those of LARC-TPI 1000 and 2000. The LARC-TPI 1500 powders are thermally stable and melt processable. The absolute molecular weight of the polymer varies from 20,000 to 30,000, indicating recurring unit numbers of about 40-60. The melt flow properties of LARC-TPI 1500 are comparable to those of other engineering plastics, such as PEEK, PSU, and PES. The flexural modulus of injection molded parts of LARC-TPI 1500 is the highest among commercial thermoplastic polymers.

Ohta, Masahiro↗
NASA NTRS1980

Study of catalyst cured LaRC-160/Celion 6000 composites

LaRC 160 polyimide was modified with a high temperature peroxide catalyst, USP-138, in an attempt to reduce the final cure temperature to below 316 C. This effort was directed at obtaining a material for 177 C use that would cure at similar temperatures to a high performance epoxy while still maintaining the good moisture resistance of a polymide material. Attempts to prepare a laminate made from Celion 6000 fiber and 5% catalyzed LaRC 160 resin gave a material with minimal properties after curing at 193 C. Acceptable properties were not obtained until a final cure temperature of 260 C was used. A control laminate containing no catalyst and cured under the same conditions had only half the level of shear strength. The catalyzed LaRC 160 prepreg was also used to examine the possibility of shortening the conventional LaRC 160 cure at 316 C. Maximum properties were obtained using a 2.5% catalyzed product with a final cure temperature of 316 C held for fifteen minutes. Differences in properties between catalyzed and uncatalyzed product disappeared, however, when the cure time at 316 C was extended to 45 minutes.

Edelman, R.↗
NASA NTRS1984

LaRC local area networks to support distributed computing

The Langley Research Center's (LaRC) Local Area Network (LAN) effort is discussed. LaRC initiated the development of a LAN to support a growing distributed computing environment at the Center. The purpose of the network is to provide an improved capability (over inteactive and RJE terminal access) for sharing multivendor computer resources. Specifically, the network will provide a data highway for the transfer of files between mainframe computers, minicomputers, work stations, and personal computers. An important influence on the overall network design was the vital need of LaRC researchers to efficiently utilize the large CDC mainframe computers in the central scientific computing facility. Although there was a steady migration from a centralized to a distributed computing environment at LaRC in recent years, the work load on the central resources increased. Major emphasis in the network design was on communication with the central resources within the distributed environment. The network to be implemented will allow researchers to utilize the central resources, distributed minicomputers, work stations, and personal computers to obtain the proper level of computing power to efficiently perform their jobs.

Riddle, E. P.↗
NASA NTRS1990

Evaluation of two bisimide additives in LARC-TPI adhesive

The processability of aromatic polyimides can be improved by the addition of bis (amide) acids or bisimides to LARC-TPI. These low molecular weight additives apparently lower the melt viscosity of aromatic polyimides without affecting the glass transition temperature. Well-consolidated, fiber reinforced composites were fabricated using this technology. LARC-TPI can be processed as a thermoplastic polyimide to form high strength bonds, however, this is generally accomplished by processing at relatively high bonding pressures. An adhesive investigation is presented on the effects of two bisimide additives to LARC-TPI in an attempt to improve the bonding process by lowering the viscosity of the material to achieve improved bond strength properties. Apparently, the high flow which is exhibited by the additives when they melt, tended to be masked by the more viscous LARC-TPI.

Progar, Donald J.↗
NASA NTRS1995

Development of LaRC (TM): IA thermoplastic polyimide coated aerospace wiring

NASA Langley has invented LaRC(exp TM) IA and IAX which are thermoplastic polyimides with good melting, thermal and chemical resistance properties. It was the objective of this contract to prepare and extrude LaRC (exp TM) polyimide onto aircraft wire and evaluate the polymers performance in this critical application. Based on rheology and chemical resistance studies at Imitec, LaRC (exp TM) IAX melts readily in an extruder, facilitating the manufacture of thin wall coatings. The polyimide does not corode the extruder, develop gel particles nor advance in viscosity. The insulated wire was tested according to MiL-W-22759E test specifications. The resulting wire coated with LaRC (exp TM) IAX displayed exceptional properties: surface resistance, non blocking, non burning, hot fluid resistance, impulse dielectric, insulation resistance, low temperature flexibility, thermal aging, wire weight, dimensions, negligible high temperature shrinkage and stripability. The light weight and other properties merit its application in satellites, missiles and aircraft applications. The extruded IAX results in a polyimide aircraft insulation without seams, outstanding moisture resistance, continuous lengths and abrasion resistance.

Keating, Jack↗
NASA NTRS1995

Troika partnership model for licensing NASA-LaRC technologies

The Technology Applications (TAG) Group at NASA Langley Research Center has currently more than 100 technologies that are ripe for commercialization. These technologies are categorized by various sectors including: Energy and the Environment; Materials and Structures; Manufacturing; Information and Communications; Transportation, and Medical/Sensor/ Instrumentation. A requirement that TAG has placed on all technologies ready for licensing is that there will be some university involvement in the technology transfer or knowledge transfer process. This model involves the troika of government (LaRC), industry and university. A number of variations on the Troika Partnership Model (TPM) were developed as a part of this ASEE Fellowship. Furthermore, five technologies were identified - three of which industrial interests have been matched: LaRC-SI, a thermoplastic that can be used as a coating; Variable Geometry Truss Manipulator Arm that can be used for nuclear waste clean -up and as scaffolding; and ADAPT (Approach to Data Management, Archive Protection, and Transmission) is a technology that could be used for a variety of multi-tasking operations over the Internet. The aim of this work was to initiate a Space Act Agreement (SAA) for at least one of these technologies using one of the options of the TPM. A preliminary partnership agreement using the SAA is currently being negotiated with NASA-LaRC, VPI and Virginia Power for the LaRC-SI thermoplastic that will be used as a coating.

Maclin, Arlene P.↗
NASA NTRS1995

Langley Research Center - Soluble Imide (LaRC-SI)

This report is about experimenting and developing uses for the new thermal plastic developed by Dr. Robert Bryant called the 'Langley Research Center - Soluble Imide' (LaRC-SI). The three developments are: the use of the LaRC-SI as a dielectric for thin film sensors, as an adhesive to place diamonds on surfaces to increase thermal conductivity, and as an intermediate layer to allow the placement of metal on aluminum nitride. The LaRC-SI was developed by Dr. Robert G. Bryant, a chemical engineer at NASA Langley Research Center. The unique properties of this material is that it is an amorphous thermoplastic. This means that it can be reformed at elevated temperature and pressures. It can be applied in the form of a spray, spin, dip coating, paint, or spread with a doctors blade. The LaRC-SI has excellent adhesive and dielectric properties. It can also be recycled. Potential applications for this material are resin for mechanical parts such as gears, bearings and valves, advanced composites like carbon fiber, high strength adhesives, thin film circuits, and as a dielectric film for placing electrical components on conductive materials.

Stang, David↗
NASA NTRS1999

Preliminary Statistical Analysis of the 1995 Evaluation by NASA LaRC of the IAI Automatic Balance Calibration Machine

The NASA Langley Research Center (LARC) participated in a national cooperative evaluation of the Israel Aircraft Industries (IAI) automatic balance calibration machine at Microcraft, San Diego in September 1995. A LaRC-designed six-component strain gauge balance was selected for test and calibration during LaRC's scheduled evaluation period. Eight calibrations were conducted using three selected experimental designs. Raw data were exported to LaRC facilities for reduction and statistical analysis using the techniques outlined in Tripp and Tcheng (1994). This report presents preliminary assessments of the results, and compares IAI calibration results with manual calibration results obtained at the Modern Machine and Tool Co., Inc. (MM & T). Newport News, VA. A more comprehensive report is forthcoming.

Tcheng, Ping↗
NASA NTRS2011

Commercialization of LARC (TradeMark) -SI Polyimide Technology

LARC(TradeMark)-SI, Langley Research Center- Soluble Imide, was developed in 1992, with the first patent issuing in 1997, and then subsequent patents issued in 1998 and 2000. Currently, this polymer has been successfully licensed by NASA, and has generated revenues, at the time of this reporting, in excess of $1.4 million. The success of this particular polymer has been due to many factors and many lessons learned to the point that the invention, while important, is the least significant part in the commercialization of this material. Commercial LARC(TradeMark)-SI is a polyimide composed of two molar equivalents of dianhydrides: 4,4 -oxydiphthalic anhydride (ODPA), and 3,3 ,4,4 -biphenyltetracarboxylic dianhydride (BPDA) and 3,4 -oxydianiline (3,4 -ODA) as the diamine. The unique feature of this aromatic polyimide is that it remains soluble after solution imidization in high-boiling, polar aprotic solvents, even at solids contents of 50-percent by weight. However, once isolated and heated above its T(sub g) of 240 C, it becomes insoluble and exhibits high-temperature thermoplastic melt-flow behavior. With these unique structure property characteristics, it was thought this would be an advantage to have an aromatic polyimide that is both solution and melt processable in the imide form. This could potentially lead to lower cost production as it was not as equipment- or labor-intensive as other high-performance polyimide materials that either precipitate or are intractable. This unique combination of properties allowed patents with broad claim coverage and potential commercialization. After the U.S. Patent applications were filed, a Small Business Innovation Research (SBIR) contract was awarded to Imtec, Inc. to develop and supply the polyimide to NASA and the general public. Some examples of demonstration parts made with LARC(TradeMark)-SI ranged from aircraft wire and multilayer printed-circuit boards, to gears, composite panels, supported adhesive tape, composite coatings, cookware, and polyimide foam. Even with its unique processing characteristics, the thermal and mechanical properties were not drastically different from other solution or meltprocessable polyimides developed by NASA. LARC(TradeMark)-SI risked becoming another interesting, but costly, high-performance material.

Bryant, Robert G.↗
NASA NTRS2013

Out of the Autoclave Fabrication of LaRC[TradeMark] PETI-9 Polyimide Laminates

The NASA Langley Research Center developed polyimide system, LaRC PETI-9, has successfully been processed into composites by high temperature vacuum assisted resin transfer molding (HT-VARTM). To extend the application of this high use temperature material to other out-of-autoclave (OOA) processing techniques, the fabrication of PETI- 9 laminates was evaluated using only a vacuum bag and oven cure. A LaRC PETI-9 polyimide solution in NMP was prepared and successfully utilized to fabricate unidirectional IM7 carbon fiber prepreg that was subsequently processed into composites with a vacuum bag and oven cure OOA process. Composite panels of good quality were successfully fabricated and mechanically tested. Processing characteristics, composite panel quality and mechanical properties are presented in this work. The resultant properties are compared to previously developed LaRC material systems processed by both autoclave and OOA techniques including the well characterized, autoclave processed LaRC PETI-5.

Cano, Robert J.↗
NASA NTRSDate not supplied

Shock-Wave/Boundary-Layer Interaction (SWBLI) Experiments in the Presence of Transition-to-Turbulence on a Flat Plate Model in the NASA LaRC 31-Inch Mach 10 Air Tunnel

Historically, there have been a limited number of studies involving Transitional Shock-Wave/Boundary-Layer Interactions (XSWBLI) in hypersonic flows, the majority of which have been performed at Mach Numbers of 7.5 and below. Additionally, there have been even fewer such experiments which incorporate non-intrusive and optical diagnostics. NASA Langley Research Center (NASA LaRC), in collaboration with The University of Texas at San Antonio (UTSA) and The University of Tennessee Space Institute (UTSI), is currently planning and preparing for a series of experimental aerodynamic tests using the NASA LaRC 31-inch Mach 10 Air Tunnel. The experiments will primarily focus on studying the dynamics of Shock-Wave/Boundary-Layer Interactions (SWBLI) in the presence of transition (XSWBLI) and turbulence (SWTBLI) on a large, flat plate model at a freestream Mach number of 10. Besides continued interest in understanding the flow at high Mach numbers, executing such tests at Mach 10 avoids some known concerns and will aid in solving new problems. XSWBLI are a highly unsteady phenomena and the generation of XSWBLI at lower Mach numbers can prove to be a significant challenge. This concern will be somewhat mitigated in the Mach 10 flow, as boundary layers become increasingly stabilized, but some difficulty in achieving transition is still expected. Modelling SWBLI in the presence of transitional and turbulent boundary layers has also proven to be difficult, so a high-Mach number experiment which applies non-intrusive and optical diagnostics will aid in solving a unique problem as well as advancing the understanding and characterization of an aerodynamic surface at Mach 10.The NASA LaRC 31-inch Wind Tunnel incorporates a test section having a cross-section of 31-inches × 31-inches and provides optical access to the test section via three (3) ultra-violet (UV) transmitting windows on the top, side, and bottom. The Mach 10 operating conditions will consist of pressures (P0) ranging from 2.4 to 10MPa (348 to 1,450 psi) at a temperature (T0) of 1,000 K (1,800 °R). The NASA LaRC 31-inch wind tunnel will deliver 1-minute blow-down runs, of which 30-45 seconds will be consumed to reach the aforementioned test conditions. The pump down time between runs will be approximately 45-60 minutes, which will provide for 6-10 test runs per day over the course of a weeklong entry. The proposed flat plate model will be constructed of stainless steel with geometry consisting of a10-inch × 30-inch upper surface and a 2-inch thickness. The model will be designed to support multiple leading-edge inserts in order to examine blunt, round, and sharp leading edges at Mach 10. Adjustments will be made to manage boundary layer thickness as well as the strength and size of the shock interaction region for each test. Measurements and diagnostics will be performed though high-speed Schlieren, on-body high-speed pressure transducers, IR thermography, and oil flow visualization. Hypersonic vehicle applications have and will continue to emerge at the forefront of aerospace. The NASA-UTSA-UTSI team realizes the value of characterizing SWBLI, XSWBLI, and SWTBLI behaviors well beyond single-digit hypersonic Mach numbers. As hypersonic vehicle speed capabilities continue to increase, measurement and diagnostic methods for Mach numbers of 10 and beyond will provide the foundation for a firm understanding of flow field behavior which will directly influence the advancement of technologies towards the design and manufacturing of high-speed aerodynamic surfaces, controls, thermal protection systems, acoustic treatments, and structural components. The use of non-intrusive and optical diagnostic methods in such experimentation is pivotal in developing the visualization and empirical data necessary to advance the aforementioned technology areas.

Shockwave/Boundary-Layer Interactions↗
NASA NTRS1980

LARC-13 adhesive development

A LARC-13 type adhesive system was developed and property data obtained that demonstrated improved thermomechanical properties superior to base LARC-13 adhesive. An improved adhesive for 589 K (600 F) use was developed by physical or chemical modification of LARC-13. The adhesive was optimized for titanium and composite bonding, and a compatible surface preparation for titanium and composite substrates was identified. The data obtained with the improved adhesive system indicated it would meet the 589 K (600 F) properties desired for application on space shuttle components. Average titanium lap shear data were: (1) 21.1 MPa (3355 psi) at RT, (2) 13.0 MPa (1881 psi) at 600 F, and (3) 16.4 MPa (2335) after aging 125 hours at 600 F and tested at 600 F.

Hill, S. G.↗
NASA NTRS1982

LARC-TPI: A multi-purpose thermoplastic polyimide

A linear thermoplastic polyimide, LARC-TPI, was characterized and developed for a variety of high temperature applications. In its fully imidized form, this material can be used as an adhesive for bonding metals such as titanium, aluminum, copper, brass, and stainless steel. LARC-TPI was evaluated as a thermoplastic for bonding large pieces of polyimide film to produce flexible, 100 void-free laminates for flexible circuit applications. The development of LARC-TPI as a potential molding powder, composite matrix resin, high temperature film and fiber is also discussed.

St.clair, A. K.↗
NASA NTRS1985

Users guide: The LaRC human-operator-simulator-based pilot model

A Human Operator Simulator (HOS) based pilot model has been developed for use at NASA LaRC for analysis of flight management problems. The model is currently configured to simulate piloted flight of an advanced transport airplane. The generic HOS operator and machine model was originally developed under U.S. Navy sponsorship by Analytics, Inc. and through a contract with LaRC was configured to represent a pilot flying a transport airplane. A version of the HOS program runs in batch mode on LaRC's (60-bit-word) central computer system. This document provides a guide for using the program and describes in some detail the assortment of files used during its operation.

Bogart, E. H.↗