Materials Literature
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The dynamic shear deformation and fracture characteristics of PC/ABS blend and ABS copolymer with regard to the relation between mechanical properties and strain rate, are studied experimentally using a torsional split Hopkinson bar at room temperature under strain rates ranging from 8 × 102 s-1 to 3.4 × 103 s-1. Frac…
In this work are described the syntheses of p-sexiphenyl and p-octiphenyl starting from 4-bromo-p-terphenyl and 4-bromo-p-quaterphenyl, respectively, by using a nickel complex in the presence of bipyridine with DMF as solvent. This type of synthesis was shown to give an improved yield as well as easy preparation and p…
Nonlinear dielectric spectroscopy in frequency domain has been applied to antiferroelectric liquid crystals in various smectic phases including antiferroelectric SmC A *, SmC FI2 * and incommensurate SmCα* phases. We have observed different characteristic third-order nonlinear dielectric spectra ϵη3* in respective pha…
We investigated second-order nonlinear optical properties of non-centrosymmetric crystals built of oblate, trigonal molecules: triphenylamine and adducts(complexes)of arsenic triiodide with sulfur, AsI3 · 3S8, and antimony triiodide with sulfur, SbI3 · 3S8. The efficiency of powder second-harmonic generation(SHG)in tr…
SiC-SiC ceramic matrix composites (CMCs) manufactured by the melt-infiltration (MI) process are leading candidates for many hot-section turbine engine components. A collaborative program between Goodrich Corporation and NASA-Glenn Research Center is aimed at determining and optimizing woven SiC/SiC CMC performance and…
The photochemical isomerization of pyrazoles was studied using ab initio methods. The singlet excited singlet state can evolve to give the Dewar isomer and the corresponding triplet state. The latter shows a lower energy and probably can be obtained with higher efficiency. The triplet state can evolve to give the corr…
In this work, a novel procedure for manufacturing an electret was designed, and the relationship between the surface voltage and other variables elucidated. The charge decay of the nonwoven electret over six weeks was also investigated. The new process quickly charges the dielectric to a voltage of between 10 and 30 k…
Seeded growths of faujasite and zeolite A were investigated by atomic force microscopy (AFM). For seeded growth, clear aluminosilicate solutions (90Na2O:xAl2O3:9SiO2:5760H2O, where x = 0.1–1.0), which are useful for faujasite or zeolite A growth on seeded faujasite or zeolite A, respectively, were prepared at 353 K. C…
Crystalline As2S3 (orpiment) is a layered-structure semiconductor whose optical properties, under ambient conditions, are determined by its diperiodic layer symmetry. We have investigated the effec...
New conjugated aryl-substituted poly(azomethine)s, termed poly(ketanil)s, have been synthesised from 1,4-phenylenediamine (or 3,3′,5,5′-tetramethylbenzidine) and two different diketones via polycondensation with the goal to obtain new materials with tunable spectroscopic properties. It is demonstrated that both the ab…
Tellurite glasses containing CuO with the nominal composition (CuO) x (TeO 2 ) 1− x , where x = 0.1, 0.2, 0.3, 0.4 and 0.5, have been prepared and investigated by x-ray photoelectron spectroscopy (XPS). The core level binding energies of Cu 2p, Te 3d, and O 1s in these glasses have been measured. The appearance of a s…
I am part of all that I have met; Yet all experience is an arch wherethro’ Gleams the untravell’d world, whose margin fades For ever and for ever when I move. How dull it is to pause, to make an end, To rust unburnish’d, not to shine in use! As tho ’ to breath were life. Life piled on life Were all too little and of o…
Small light‐weight satellites and space vehicles under development for future NASA missions have reduced thermal mass and are strongly affected by changes in orbital conditions, resulting in large temperature variations. Restrictions on payload weight and volume limit the usefulness of many thermal control technologie…
Surfactants have been tried as inhibitors of pitting corrosion of various materials such as stainless steels and aluminum alloys. In order to understand the structure-performance relationship in pitting inhibition, surfactants of different charged headgroups, i.e. , anionic sodium dodecylsulfate (SDS), cationic dodecy…
A series of polymer electrolytes, based on ionic liquid (EMIm) 3 PO 4 , and the polymers PAN, PVdF, PVdF-HFP, PVA and PEO were prepared as thin-foils, using the casting technique. The composite electrolytes showed conductivity at a level of ca. 10 mS/cm, apart from the system PEO-(EMIm) 3 PO 4 . The electrochemical st…
In the last 10 years the electron backscatter diffraction (EBSD) technique has developed into a powerful tool for the crystallographic analysis of materials in the scanning electron microscope. In particular the emergence of computer algorithms for the fully automated analysis of diffraction patterns has pushed the te…
The role of nonhydrodynamic relaxing processes in collective dynamics of pure liquids is studied within a generalized collective modes approach. A five-variable model of generalized hydrodynamics is solved analytically in long-wavelength limit. Among five collective modes we found three hydrodynamic and two relaxing k…
5,10,15,20-Tetrakis-[3α-(2,3,4,6-tetra- O -benzyl-β-D-glucopyranosyl)-5β-cholan-24-yl]porphyrin and 5,10,15,20-tetrakis-[3α-(2,3,4,6-tetra- O -benzyl-β-D-galactopyranosyl)-5β-cholan-24-yl]porphyrin were synthesized by condenzation of the respective steroid aldehydes and pyrrole-1-yl magnesium bromide.
The kinetic mechanism of the reaction between three kinds of silica glasses and HF acid solution was investigated systematically. The results indicate that the reaction rate is controlled by the chemical reaction, and depends on the breaking of the siloxane bonds in ≡Si-O-Si≡ network structure. The main factors influe…
This study is concerned with the split Hopkinson bar method for tension test of strip specimens. The split Hopkinson bar method (SHB) has been used for impact tests such as compression and shearing, and is currently modified for tension test. It is demanded that the impact tensile behaviour of high-tensile strength st…