790 research outputs found
Acetylene terminated aspartimides and resins therefrom
Acetylene terminated aspartimides are prepared using two methods. In the first, an amino-substituted aromatic acetylene is reacted with an aromatic bismaleimide in a solvent of glacial acetic acid and/or m-cresol. In the second method, an aromatic diamine is reacted with an ethynyl containing maleimide, such an N-(3-ethynyl phenyl) maleimide, in a solvent of glacial acetic acid and/or m-cresol. In addition, acetylene terminated aspartimides are blended with various acetylene terminated oligomers and polymers to yield composite materials exhibiting improved mechanical properties
N-(3-ethynylphenyl)maleimide
Acetylene terminated aspartimides are prepared using two methods. In the first, an amino-substituted aromatic acetylene is reacted with an aromatic bismaleimide in a solvent of glacial acetic acid and/or m-cresol. In the second method, an aromatic diamine is reacted with an ethynyl containing maleimide, such as N-(3-ethynylphenyl) maleimide, in a solvent of glacial acetic acid and/or m-cresol. In addition, acetylene terminated aspartimides are blended with various acetylene terminated oligomers and polymers to yield composite materials exhibiting improved mechanical properties
Polyimides with improved compression moldability
The semicrystalline polyimide prepared by reaction of 3,3',4,4' benzophenonetetracarboxylic (BTDA) and 1,3-bis(4-aminophenoxy 4' benzoyl) benzene (1,3-BABB) is modified so that it can be more readily processed to form adhesive bonds, moldings, and composites. The stoichiometric ratio of the two monomers, BTDA and 1,3-BABB is controlled so that the intermediate polyamide acid is of a calculated molecular weight. A polyimide acid with excess anhydride groups is then reacted with the stoichiometrically required amount of monofunctional aromatic or aliphatic amine required for complete endcapping. The stoichiometrically offset, encapped polyimide is processed at lower temperatures and pressures than the unmodified high molecular weight polyimide with the same repeat unit, and exhibits an improved melt stability
In-flight calibration of the high-gain antenna pointing for the Mariner Venus-Mercury 1973 spacecraft
The methods used to in-flight calibrate the pointing direction of the Mariner Venus-Mercury 1973 spacecraft high gain antenna and the achieved antenna pointing accuracy are described. The overall pointing calibration was accomplished by performing calibration sequences at a number of points along the spacecraft trajectory. Each of these consisted of articulating the antenna about the expected spacecraft-earth vector to determine systematic pointing errors. The high gain antenna pointing system, the error model used in the calibration, and the calibration and pointing strategy and results are discussed
Improving Literacy Rates For Students With Dyslexia in a Rural School District
This applied research study aimed to improve literacy rates for students identified as having dyslexic tendencies in the Lynn County School District (LCSD). The need to improve literacy rates of students with dyslexia in the Reaching Reading Success Program was identified through Mississippi K-3 Assessment Support System data. Using the two elements found in the program evaluation, accurate identification of dyslexic students and multisensory interventions the study sought to improve the literacy rates for students with dyslexia in kindergarten. Assessment, survey, and interview data were used in this applied research study to determine success. The findings indicated early identification, multi-sensory remediation, and organizational learning does improve literacy rates for students with dyslexic characteristics in kindergarten
Crushed Rock Bases
Prepared in cooperation with the US Department of Transportation, Federal Highway Administration.
Gradations containing high, medium, and low percentages of fines were evaluated by laboratory tests and by behavioral responses in situ. Significant differences in strength parameters were not found. Differences in densities were not significant
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