NASA Scientific and Technical Aerospace Reports

local, intermediate, and long range structure in a series of mesophase systems and have constructed correlations between NMR
observables and molecular size, topology, and network structure. The goal of this research was the development of a strong
LLNL capability in the characterization of mesophased materials by NMR spectroscopy that will lead to a capability in
rational synthesis of such materials and a fundamental understanding of their structure-property relationships. We demonstrate
our progress towards attaining this goal by presenting NMR results on four mesophased model systems.
NTIS
Nuclear Magnetic Resonance; Molecular Structure; Optical Resonance
20040120980 NASA Kennedy Space Center, Cocoa Beach, FL, USA
Ferromagnetic Conducting Lignosulfonic Acid-doped Polyaniline Nanocomposites
Viswansthan, Tito, Inventor; Berry, Brian, Inventor; July 20, 2004; 13 pp.; In English
Patent Info.: Filed 16 Nov. 2001; US-Patent-6,764,617; US-Patent-Appl-SN-994996; US-Patent-Appl-SN-249563;
NASA-Case-KSC-12190-1; No Copyright; Avail: CASI; A03, Hardcopy
A conductive ferromagnetic composition of matter comprising sulfonated lignin or a sulfonated polyflavonoid, or
derivatives thereof, and ferromagnetic iron oxide particles is disclosed. Among the uses of the composition is to shield
electromagnetic radiation. The ferromagnetic iron oxide particles of the composition are surprisingly stable to acid, and are
easily and inexpensively formed from iron cations in solution.
Author
Nanocomposites; Ferromagnetic Materials; Sulfonic Acid
20040120987 NASA Langley Research Center, Hampton, VA, USA
Characterization of the Nonlinear Elastic Properties of Graphite/Epoxy Composites Using Ultrasound
Prosser, William H.; Green, Robert E., Jr.; Journal of Reinforced Plastics and Composites; March 1990; Volume 9,
pp. 162-173; In English; Original contains black and white illustrations
Contract(s)/Grant(s): NGT-21-001-802; Copyright; Avail: CASI; A03, Hardcopy
The normalized change in ultrasonic ‘natural’ velocity as a function of stress and temperature was measured in a
unidirectional laminate of T300/5208 graphite/epoxy composite using a pulsed phase locked loop ultrasonic interferometer.
These measurements were used together with the linear (second order) elastic moduli to calculate some of the nonlinear (third
order) moduli of this material.
Author
Elastic Properties; Graphite-Epoxy Composites; Nonlinearity; Ultrasonics; Characterization; Mechanical Properties
20040121063 NASA Langley Research Center, Hampton, VA, USA
Effect of Stress on Energy Flux Deviation of Ultrasonic Waves in Ultrasonic Waves in GR/EP Composites
Prosser, William H.; Kriz, R. D.; Fitting, Dale W.; Proceedings of the IEEE 1990 Ultrasonic Symposium; [1990], pp. 961-964;
In English; Original contains black and white illustrations; Copyright; Avail: CASI; A01, Hardcopy
Ultrasonic waves suffer energy flux deviation in graphite/epoxy because of the large anisotropy. The angle of deviation
is a function of the elastic coefficients. For nonlinear solids, these coefficients and thus the angle of deviation is a function of
stress. Acoustoelastic theory was used to model the effect of stress on flux deviation for unidirectional T300/5208 using
previously measured elastic coefficients. Computations were made for uniaxial stress along the x3 axis fiber axis) and the x1
axis for waves propagating in the x1x3 plane. These results predict a shift as large as three degrees for the quasi-transverse
wave. The shift in energy flux offers new nondestructive technique of evaluating stress in composites.
Author
Ultrasonic Radiation; Transverse Waves; Graphite-Epoxy Composites
20040121068 NASA Langley Research Center, Hampton, VA, USA
Tensile Stress Acoustic Constants of Unidirectional Graphite/Epoxy Composites
Prosser, W. H.; Journal of Reinforced Plastics and Composites; March 1990; Volume 9, pp. 127-133; In English; Original
contains black and white illustrations; Copyright; Avail: CASI; A02, Hardcopy
Previously, the stress acoustic constants (SAC’s) of unidirectional graphite/epoxy composites were measured to determine
the nonlinear moduli of this material. These measurements were made under compressive loading in order to obtain the
sufficient number of values needed to calculate these moduli. However, because their strength in tension along fiber directions
can be several times greater, most composites are used under tensile loading. Thus, it is important to characterize the nonlinear
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