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  • 1
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    Improved high-temperature resistant matrix resins (1989)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A study was performed with the objective of developing matrix resins that exhibit improved thermo-oxidative stability over state-of-the-art high temperature resins for use at temperatures up to 644 K (700 F) and air pressures up to 0.7 MPa (100 psia). The work was based upon a TRW discovered family of polyimides currently licensed to and marketed by Ethyl Corporation as EYMYD(R) resins. The approach investigated to provide improved thermo-oxidative properties was to use halogenated derivatives of the diamine, 2, 2-bis (4-(4-aminophenoxy)phenyl) hexafluoropropane (4-BDAF). Polyimide neat resins and Celion(R) 12,000 composites prepared from fluorine substituted 4-BDAF demonstrated unexpectedly lower glass transition temperatures (Tg) and thermo-oxidative stabilities than the baseline 4-BDAF/PMDA polymer.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-CR-180826 , NAS 1.26:180826
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Intersubband Transitions in InAs/AlSb Quantum Wells (2003)
    In:  CASI
    Details
    Publication Date: 2019-08-16
    Description: We have studied intersubband transitions in InAs/AlSb quantum wells experimentally and theoretically. Experimentally, we performed polarization-resolved infrared absorption spectroscopy to measure intersubband absorption peak frequencies and linewidths as functions of temperature (from 4 K to room temperature) and quantum well width (from a few nm to 10 nm). To understand experimental results, we performed a self-consistent 8-band k-p band-structure calculation including spatial charge separation. Based on the calculated band structure, we developed a set of density matrix equations to compute TE and TM optical transitions self-consistently, including both interband and intersubband channels. This density matrix formalism is also ideal for the inclusion of various many-body effects, which are known to be important for intersubband transitions. Detailed comparison between experimental data and theoretical simulations is presented.
    Keywords: Electronics and Electrical Engineering
    Type: MRS Fall Meeting; Jan 01, 2003; Boston, MA; United States
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    NASA TECHNICAL REPORTS
  • 3
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    Microscopic Modeling of Intersubband Resonances in InAs/AlSb Quantum Wells (2003)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: Linear absorption spectra from intersubband resonance in InAs/AlSb quantum wells are analyzed theoretically using the intersubband semiconductor Bloch equation approach. Our model goes beyond the Hartree-Fock approximation and treats particle-particle correlations under the second Born approximation. Electron-electron and -LO phonon scatterings from such a treatment describe intrinsic line broadening to the intersubband resonance. Electron subbands are determined self-consistently with a spurious-state-free 8-band k.p Hamiltonian under the envelope function approximation. To compare with experimental measurements, we also included line broadening due to electron-interface roughness scattering. Excellent agreement was achieved for temperature-dependent absorption spectra in the mid-infrared frequency range, after taking into careful account the interplay of material parameters, nonparabolicity in bandstructure, and many-body effects.
    Keywords: Solid-State Physics
    Type: 11th International Conference on Narrow Gap Semiconductors; Jun 16, 2003 - Jun 20, 2003; Buffalo, NY; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    TRW A-type polyimide resin for filament winding (1974)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Studies were conducted to select a TRW A-type polyimide resin that would be suitable for fabrication of filament wound reinforced plastics structures. Several different formulations were evaluated after which the P105AC formulation was selected as the most promising. Procedures were developed for preparing P105AC/S-glass roving prepreg and for fabricating filament wound structural composites. Composites were fabricated and then tested in order to obtain tensile and shear strength information. Small, closed-end cylindrical pressure vessels then were fabricated using a stainless steel liner and end-fittings with a P105AC/S-glass polar-wound overwrap. These pressure vessels were cured in an air circulating oven without augmented pressure. It was concluded upon completion of this study that the P105AC resin system is suitable for filament winding; that low void content, high strength composites are obtained by the filament winding process; and that augmented pressure is not required to effect the fabrication of filament wound P105AC composites.
    Keywords: MATERIALS, NONMETALLIC
    Type: National Symposium and Exhibition; Apr 23, 1974 - Apr 25, 1974; Buena Park, CA
    Format: text
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    NASA TECHNICAL REPORTS
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