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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 2005-2016 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyamides were prepared from linear, aliphatic dicarboxylic acids of six to twelve carbon atoms with 1,4-cyclohexanebis(methylamine), 1,4-cyclohexanebis (ethylamine), p-xylylenediamine, and p-phenylenebis(ethylamine). Melting points, glass transition temperatures, densities, and moisture regains were compared for the polymers to determine the relative effect of the cyclohexylene and phenylene linkages. While polyamides containing the trans-cyclohexylene group possessed higher glass transition temperatures than their aromatic counterparts, melting behavior was not as consistent. The odd-even rule, which states that polyamides with an even number of methylene linkages between the ring and the functional group melt higher than those with an odd number of such linkages, was violated in the cycloaliphatic systems. The Tg of ring-containing polyamide fibers was not dependent solely upon ring concentration, but was influenced by the molecular fit of the ringed intermediate in the polymer chains. Molecular fit appears to affect the Tg and melting point of alicyclic polyamides to a greater extent than the aromatic analogs. Differences in Tg, both within and among the polymer series, was not explained by either density or the degree of crystallinity.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 8 (1970), S. 3089-3111 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several series of nylon 66 copolyamides were prepared with up to 30 mole-% substitution of ringed comonomers of the type X-(CH2)n-R-(CH2)n-X, where n = 0, 1, or 2; X = -NH2 or —CO2H; and R = phenylene, cyclohexylene, or naphthyle. The ring structure was correlated with glass transition temperature and melting point. The important features of ring structure fall into the following categories: ring isomerism, aromaticity, diamine vs. diacid substitution, chain length, and ring substitution. Proper “fit” (isomorphism) of the comonomer into the nylon 66 chain appears to be the main criterion for ringed copolymers of high Tg and high melting point.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2019-06-28
    Description: The technological readiness of a long-life multipropellant resistojet for space station auxiliary propulsion is demonstrated. A laboratory model resistojet made from grain-stabilized platinum served as a test bed to evaluate the design characteristics, fabrication methods, and operating strategies for an engineering model multipropellant resistojet developed under contract by the Rocketdyne Division of Rockwell International and Technion Incorporated. The laboratory model thruster was subjected to a 2000-hr, 2400-thermal-cycle endurance test using carbon dioxide propellant. Maximum thruster temperatures were approximately 1400 C. The post-test analyses of the laboratory model thruster included an investigation of component microstructures. Significant observations from the laboratory model thruster are discussed as they relate to the design of the engineering model thruster.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-TM-89854 , E-3521 , NAS 1.15:89854 , AIAA PAPER 87-0993
    Format: application/pdf
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  • 4
    Publication Date: 2019-06-28
    Description: A self contained, single use hose and tubing cleaning module which utilizes available water supplies without requiring access to precision cleaning facilities is presented. The module is attached to the water source at the inlet side and to the hose or tubing to be cleaned at the outlet side. The water flows through a water purification zone, a detergent dispensing zone, a filtration zone before the detergent laden water flows into the tubing to clean the tubing walls. The module contains an embedded pad which is impregnated with a pH indicator to indicate to the user when the detergent has dissolved and rinsing of the tubing begins.
    Keywords: MECHANICAL ENGINEERING
    Format: application/pdf
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  • 5
    Publication Date: 2019-06-28
    Description: The document describes the NASA Standard Reference Model (NASREM) Architecture for the Space Station Telerobot Control System. It defines the functional requirements and high level specifications of the control system for the NASA space Station document for the functional specification, and a guideline for the development of the control system architecture, of the 10C Flight Telerobot Servicer. The NASREM telerobot control system architecture defines a set of standard modules and interfaces which facilitates software design, development, validation, and test, and make possible the integration of telerobotics software from a wide variety of sources. Standard interfaces also provide the software hooks necessary to incrementally upgrade future Flight Telerobot Systems as new capabilities develop in computer science, robotics, and autonomous system control.
    Keywords: MECHANICAL ENGINEERING
    Type: NASA-CR-185078 , NAS 1.26:185078 , PB89-193940 , NIST/TN-1235-89
    Format: application/pdf
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