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  • 1
    Electronic Resource
    Electronic Resource
    Mechanical Properties of LaRCTM-IA and ULTEM® Melt-Extruded Fibers and Melt-Pressed Films (1998)
    Springer
    Advanced performance materials 5 (1998), S. 193-200 
    Details
    ISSN: 1572-8765
    Keywords: melt-extrusion ; polyimide fibers ; tensile properties ; LaRCTM-IA ; ULTEM®
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract LaRCTM-IA, the polyimide prepared with 3,4′-oxydianiline (3,4′-ODA) and oxydiphthalic anhydride (ODPA), is useful as a film, coating, adhesive, and composite matrix. The high temperature capability and fire-resistance of polyimides also makes them attractive candidates for textile fibers for a variety of uses in the automotive, chemical, and aerospace industries. This research describes for the first time the melt-spinning of phthalic anhydride endcapped LaRCTM-IA and the effects of processing conditions on the mechanical properties of slightly-drawn fibers. Average draw ratios varied from 1 to 3.9. Tensile strengths ranged from 103 to 159 MPa; moduli ranged from 2.80 to 3.21 GPa; elongations at break ranged from 14 to 103%. For comparison, tensile properties of compression-molded films prepared at the same temperatures are also reported. Melt-extruded fibers and melt-pressed films of another thermoplastic, ULTEM®, were also fabricated. ULTEM® fibers exhibited tensile strengths ranging from 138 to 207 MPa for average draw ratios of 4.5 to 10.3. Moduli ranged from 2.70 to 3.22 GPa. Elongations at break ranged from 47 to 111%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008630431071
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Polyimide Fibers (1997)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A polyimide fiber having textile physical property characteristics and the process of melt extruding same from a polyimide powder. Polyimide powder formed as the reaction product of the monomers 3.4'-ODA and ODPA, and endcapped with phthalic anhydride to control the molecular weight thereof, is melt extruded in the temperature range of 340? C. to 360? C. and at heights of 100.5 inches, 209 inches and 364.5 inches. The fibers obtained have a diameter in the range of 0.0068 inch to 0.0147 inch; a mean tensile strength in the range of 15.6 to 23.1 ksi; a mean modulus of 406 to 465 ksi; and a mean elongation in the range of 14 to 103%.
    Keywords: Nonmetallic Materials
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    LaRC-ITPI/arylene ether copolymers (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: As part of an effort to develop high performance structural resins for aerospace applications, work has continued on block copolymers containing imide and arylene ether segments. The arylene ether block used in this study contains a bulky fluorene group in the polymer backbone while the imide block contains an arylene ketone segment similar to that in the arylene ether block and has been named LaRC-ITPI. A series of imide/arylene ether block and segmented copolymers were prepared and characterized. Films were prepared from these copolymers and mechanical properties were measured.
    Keywords: NONMETALLIC MATERIALS
    Type: NASA-TM-104099 , NAS 1.15:104099
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Vacuum powder injector and method of impregnating fiber with powder (1993)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A method and apparatus uniformly impregnate stranded material with dry powder such as low solubility, high melt flow polymer powder to produce, for example, composite prepregs. The stranded material is expanded in an impregnation chamber by an influx of air so that the powder, which may enter through the same inlet as the air, penetrates to the center of the stranded material. The stranded material then is contracted for holding the powder therein. The stranded material and powder may be pulled through the impregnation chamber in the same direction by vacuum. Larger particles of powder which do not fully penetrate the stranded material may be combed into the stranded material and powder which does not impregnate the stranded material may be collected and reused.
    Keywords: ENGINEERING (GENERAL)
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Modified LaRC(TM)-IA Polyimides (1994)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Modified versions of thermoplastic polyimide LaRC(TM)-IA incorporate various amounts of additional, rigid moieties into backbones of LaRC(TM)-IA molecules. Modified versions more resistant to solvents and exhibit higher glass-transition temperatures, yet retain melt-flow processability of unmodified LaRC(TM)-IA.
    Keywords: MATERIALS
    Type: LAR-15083 , NASA Tech Briefs (ISSN 0145-319X); 18; 9; P. 96
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Recent Advances in Thermoplastic Puncture-Healing Polymers (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The motivation for this work is to develop self-healing polymeric materials to enable damage tolerant systems, and to tailor puncture healing for use temperatures and applications. This will be a benefit in environments and conditions where access for manual repair is limited or impossible, or where damage may not be detected.
    Keywords: Nonmetallic Materials
    Type: NF1676L-10583 , LAR-17706,1 , AIAA Infotech at Aerospace 2010; Apr 20, 2010 - Apr 22, 2010; Atlanta, GA; United States
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    NASA TECHNICAL REPORTS
  • 7
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    Engineering Polymer Blends for Impact Damage Mitigation (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Structures containing polymers such as DuPont's Surlyn 8940, demonstrate puncture healing when impacted by a 9 millimeter projectile traveling from speeds near 300 meters per second (1,100 feet per second) to hypervelocity impacts in the micrometeoroid velocity range of 5 kilometers per second (16,000 feet per second). Surlyn 8940 puncture heals over a temperature range of minus 30 degrees Centigrade to plus 70 degrees Centigrade and shows potential for use in pressurized vessels subject to impact damage. However, such polymers are difficult to process and limited in applicability due to their low thermal stability, poor chemical resistance and overall poor mechanical properties. In this work, several puncture healing engineered melt formulations were developed. Moldings of melt blend formulations were impacted with a 5.56 millimeter projectile with a nominal velocity of 945 meters per second (3,100 feet per second) at about 25 degrees Centigrade, 50 degrees Centigrade and 100 degrees Centigrade, depending upon the specific blend being investigated. Self-healing tendencies were determined using surface vacuum pressure tests and tensile tests after penetration using tensile dog-bone specimens (ASTM D 638-10). For the characterization of tensile properties both pristine and impacted specimens were tested to obtain tensile modulus, yield stress and tensile strength, where possible. Experimental results demonstrate a range of new puncture healing blends which mitigate damage in the ballistic velocity regime.
    Keywords: Nonmetallic Materials; Space Transportation and Safety
    Type: NASA/TM-2016-219002 , L-20549 , NF1676L-20985
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Radial-Electric-Field Piezoelectric Diaphragm Pumps (2009)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: In a recently invented class of piezoelectric diaphragm pumps, the electrode patterns on the piezoelectric diaphragms are configured so that the electric fields in the diaphragms have symmetrical radial (along-the-surface) components in addition to through-the-thickness components. Previously, it was accepted in the piezoelectric-transducer art that in order to produce the out-of-plane bending displacement of a diaphragm needed for pumping, one must make the electric field asymmetrical through the thickness, typically by means of electrodes placed on only one side of the piezoelectric material. In the present invention, electrodes are placed on both sides and patterned so as to produce substantial radial as well as through-the-thickness components. Moreover, unlike in the prior art, the electric field can be symmetrical through the thickness. Tests have shown in a given diaphragm that an electrode configuration according to this invention produces more displacement than does a conventional one-sided electrode pattern. The invention admits of numerous variations characterized by various degrees of complexity. Figure 1 is a simplified depiction of a basic version. As in other piezoelectric diaphragm pumps of similar basic design, the prime mover is a piezoelectric diaphragm. Application of a suitable voltage to the electrodes on the diaphragm causes it to undergo out-of-plane bending. The bending displacement pushes a fluid out of, or pulls the fluid into, a chamber bounded partly by the diaphragm. Also as in other diaphragm pumps in general, check valves ensure that the fluid flows only in through one port and only out through another port.
    Keywords: Man/System Technology and Life Support
    Type: LAR-16363-1 , NASA Tech Briefs, May 2009; 24
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Electro-Active Device Using Radial Electric Field Piezo-Diaphragm for Control of Fluid Movement (2005)
    In:  CASI
    Details
    Publication Date: 2019-08-13
    Description: A fluid-control electro-active device includes a piezo-diaphragm made from a ferroelectric material sandwiched by first and second electrode patterns configured to introduce an electric field into the ferroelectric material when voltage is applied thereto. The electric field originates at a region of the ferroelectric material between the first and second electrode patterns, and extends radially outward from this region of the ferroelectric material and substantially parallel to the plane of the ferroelectric material. The piezo-diaphragm deflects symmetrically about this region in a direction substantially perpendicular to the electric field. An annular region coupled to and extending radially outward from the piezo-diaphragm perimetrically borders the piezo-diaphragm, A housing is connected to the region and at least one fluid flow path with piezo-diaphragm disposed therein.
    Keywords: Fluid Mechanics and Thermodynamics
    Format: text
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    NASA TECHNICAL REPORTS
  • 10
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    Nanotubular Toughening Inclusions (2015)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: Conventional toughening agents are typically rubbery materials or small molecular weight molecules, which mostly sacrifice the intrinsic properties of a matrix such as modulus, strength, and thermal stability as side effects. On the other hand, high modulus inclusions tend to reinforce elastic modulus very efficiently, but not the strength very well. For example, mechanical reinforcement with inorganic inclusions often degrades the composite toughness, encountering a frequent catastrophic brittle failure triggered by minute chips and cracks. Thus, toughening generally conflicts with mechanical reinforcement. Carbon nanotubes have been used as efficient reinforcing agents in various applications due to their combination of extraordinary mechanical, electrical, and thermal properties. Moreover, nanotubes can elongate more than 20% without yielding or breaking, and absorb significant amounts of energy during deformation, which enables them to also be an efficient toughening agent, as well as excellent reinforcing inclusion. Accordingly, an improved toughening method is provided by incorporating nanotubular inclusions into a host matrix, such as thermoset and thermoplastic polymers or ceramics without detrimental effects on the matrix's intrinsic physical properties.
    Keywords: Mechanical Engineering; Composite Materials; Structural Mechanics
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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