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  • 1
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    Vectran Fiber Time-Dependent Behavior and Additional Static Loading Properties (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-11
    Description: Vectran HS appears from literature and testing to date to be an ideal upgrade from Kevlar braided cords for many long-term, static-loading applications such as tie-downs on solar arrays. Vectran is a liquid crystalline polymer and exhibits excellent tensile properties. The material has been touted as a zero creep product. Testing discussed in this report does not support this statement, though the creep is on the order of four times slower than with similar Kevlar 49 products. Previous work with Kevlar and new analysis of Vectran testing has led to a simple predictive model for Vectran at ambient conditions. The mean coefficient of thermal expansion (negative in this case) is similar to Kevlar 49, but is not linear. A positive transition in the curve occurs near 100 C. Out-gassing tests show that the material performs well within parameters for most space flight applications. Vectran also offers increased abrasion resistance, minimal moisture regain, and similar UV degradation. The effects of material construction appear to have a dramatic effect in stress relaxation for braided Vectran. To achieve the improved relaxation rate, upgrades must also examine alternate construction or preconditioning methods. This report recommends Vectran HS as a greatly improved replacement material for applications where time-dependent relaxation is a major factor.
    Keywords: Composite Materials
    Type: NASA/TM-2004-212773 , Rept-2005-00446-0
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Contamination of Critical Surfaces from NVR Glove Residues Via Dry Handling and Solvent Cleaning (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: Gloves are often used to prevent the contamination of critical surfaces during handling. The type of glove chosen for use should be the glove that produces the least amount of non-volatile residue (NVR). This paper covers the analysis of polyethylene, nitrile, latex, vinyl, and polyurethane gloves using the contact transfer and gravimetric determination methods covered in the NASA GSFC work instruction Gravimetric Determination and Contact Transfer of Non-volatile Residue (NVR) in Cleanroom Glove Samples, 541-WI-5330.1.21 and in the ASTM Standard E-1731M-95, Standard Test Method for Gravimetric Determination of Non-Volatile Residue from Cleanroom Gloves. The tests performed focus on contamination of critical surfaces at the molecular level. The study found that for the most part, all of the gloves performed equally well in the contact transfer testing. However, the polyethylene gloves performed the best in the gravimetric determination testing, and therefore should be used whenever solvent contact is a possibility. The nitrile gloves may be used as a substitute for latex gloves when latex sensitivity is an issue. The use of vinyl gloves should be avoided, especially if solvent contact is a possibility. A glove database will be established by Goddard Space Flight Center (GSFC) Code 541 to compile the results from future testing of new gloves and different glove lots.
    Keywords: Nonmetallic Materials
    Type: NASA/TM-2004-212752 , Rept-2004-01401-1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Determination of Fiber Volume in Carbon/Cyanate Ester Composites Using Thermogravimetric Analysis (TGA) (2007)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The resin content, and by extension the fiber volume, of carbon fiber/cyanate ester composite laminates are measured using thermogravimetric analysis (TGA). Conventional measurement involves acid digestion of the laminate to determine resin content. The mean difference between techniques is 0.03%. In addition to eliminating the hazards and environmental impact of standard acid digestion, the TGA technique allows quantification of errors associated with fiber volume measurements, e.g. incomplete resin removal or fiber degradation. An additional benefit of the TGA technique is a reduction in sample size requirements, allowing the examination of fiber volume changes in complex shapes.
    Keywords: Composite Materials
    Type: NASA/TM-2006-214143 , Rept-2006-01562-1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Analysis of Black Bearing Balls from a Space Shuttle Body Flap Actuator (2005)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A significantly deteriorated ball bearing mechanism from a body flap actuator on Space Shuttle OV-103 was disassembled and the balls submitted for analysis in conjunction with Return to Flight activities. The OV-103 balls, referred to as the "black balls", were subjected to X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) and Raman micro spectroscopy, surface profilometry, and optical and electron microscopy. The spectroscopic results in combination with microscopy analysis allowed a determination of the lubricant degradation pathway. The chemical attack mechanism does not adequately explain the unique visual appearance of the black balls. Numerous efforts have unsuccessfully focused on duplication of the phenomena causing this unique surface structure and appearance of the black balls. Further detail will be presented supporting these conclusions along with plausible explanations of the unique black appearance to the balls.
    Keywords: Metals and Metallic Materials
    Type: WTC2005-63539 , WTC2005 World Tribology Congress III; Sep 12, 2005 - Sep 16, 2005; Washington, DC; United States
    Format: application/pdf
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  • 5
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    Non-Volatile Residue (NVR) Contamination from Dry Handling and Solvent Cleaning (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This slide presentation reviews the testing for Non-Volatile Residue contamination transferred to surfaces from handling and solvent cleaning. Included in the presentation is a list of the items tested, formal work instructions dealing with NVR. There is an explanation of the Gravimetric determination method used to test the NVR in a variety of items, i.e., Gloves, Swabs, Garments, Bagging material, film and Wipes. Another method to test for contamination from NVR is the contact transfer method. The use of this method for testing gloves, garments, bagging material and film is explained. Certain equations use in NVR analysis and the use of a database for testing of NVR in consumables are reviewed.
    Keywords: Chemistry and Materials (General)
    Type: 2009 Contamination, Coatings, and Materials Workshop; Jul 23, 2009; Greenbelt, MD; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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