Materials Literature
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Low viscosity high birefringence nematic liquid crystalline compounds and mixtures are described. They belong to the families of 4'-alkyl-3-fluoro-4-isothiocyanatobiphenyls, 4"-alkyl-3,5-difluoro-4-isothiocyanatoterphenyls, 4'-alkyl-3-fluoro-4-isothiocyanatotolanes and 4'-(4-alkylphenyl)-3,5-difluoro-4-isothiocyanatot…
Abstract Lithium‐chromium ferrites Li 0.5 Fe 2.5– x Cr x O 4 (0 ≤ x ≤ 1.55) were studied using X‐ray diffraction, magnetization measurements and Mössbauer spectroscopy. X‐ray diffraction patterns show that all samples have cubic spinel structure. The temperature dependent magnetic measurements revealed that a magnetic…
Room temperature vulcanized silicone rubber (RTV SIR) coatings are employed in order to improve the pollution performance of high voltage ceramic insulators by imparting surface hydrophobicity. In this paper, the performance of three RTV SIR coatings containing different fillers is investigated in a salt-fog test. Alu…
A comparative study on acid and hydrothermal methods as ways to reduce interlamellar charge has been carried out on a vermiculite. This study showed that the application of the hydrothermal treatment as a previous step to pillaring the vermiculites, reported here for the first time, is a new route to obtain the porous…
Abstract The microstructural, rheological, and mechanical properties of polymer blends composed of continuous polypropylene (PP) and styrene‐butadiene rubber (SBR) phases are reported. Two series of materials are studied: a commercial SBR and PP fraction varied over 20–45 wt% and four custom synthesized SBR materials,…
Abstract Polyfuran (PFu), poly(2‐bromoaniline) (P2BrAn), and poly(2‐bromoaniline)/polyfuran (P2BrAn/PFu) composites were synthesized by coupling using various solvents and oxidants. 2‐Bromoaniline (2BrAn) was polymerized using FeCl 3 and (NH 4 ) 2 S 2 O 8 in aqueous HCl medium. PFu was synthesized using FeCl 3 and SbC…
Here we report the preparation of nanocrystalline silica capped yttrium silicate doped with cerium and a study on its photoluminescence (PL) properties. The preparation method presented is simple and unique and can easily be scaled up for bulk production. The material shows blue luminescence at room temperature, and i…
Angle-resolved photoemission spectroscopy shows that a Mott-Hubbard type metal-insulator transition occurs at the Rb adsorbed surface of the layered charge-density-wave compound 1T-TaS2. The transition is driven by adsorption induced modifications of the charge-density wave and of the interlayer coupling, leading to a…
The VUV excited luminescent properties of REBa3B9O18 (RE = Lu, Tb, Gd, Eu) were investigated. The bands near 160 nm in the VUV excitation spectra of those compounds are attributed to the host absorptions; at the same time, the energy of host absorption is shifted to a higher energy region with decreasing RE3+ radius.…
Abstract In an attempt to develop a desirable resin formulation for spilled oil absorption, segmented polyurethanes of various types and lengths of hard and soft segments have been synthesized and tested for X‐ray diffraction, thermal, mechanical, and dynamic mechanical properties in addition to oil and water absorpti…
The magnetic, resistive, and structural properties of $A$-site layer-ordered ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ba}}_{x}\mathrm{Mn}{\mathrm{O}}_{3}$ materials ($x=0.44$, 0.48, 0.5, and 0.52) have been investigated. Ferromagnetic properties have been observed for samples with $x<0.5$. Ferromagnetic and antife…
Abstract In this work, fluorine‐containing copolyimides were synthesized from 6FDA dianhydride and different ratios of BisAAF and PPD diamines. Properties, such as composition, viscosity, dielectric constant, glass‐transition temperature, thermal decomposition temperature, tensile characteristics, and transmittance, w…
A numerical simulation of the aircraft impact into the exterior columns of the World Trade Center (WTC) was done using LS-DYNA. For simplification, the fuselage was modeled as a thin-walled cylinder, the wings were modeled as box beams with a fuel pocket, and the engines were represented as rigid cylinders. The exteri…
Different characterization methods (optical microscopy, Karl Ficher titration (KF), XRPD, and solid-state FTIR) were used to identify the two polymorphs and one hydrate of stavudine. The two forms are monotropically related, and form 1 is the stable polymorph. The effects of solvent, impurities, supersaturation, and m…
Abstract We studied the condensing reaction of sebacic acid and glycerol and prepared biodegradable elastomers. Swelling experiments proved that the elastomers were crosslinked polyesters consisting of both insoluble parts (gel) and soluble parts (sol), but the content of sol was higher than gel. X‐ray diffraction ana…
Abstract This article describes the preparation, characterization, and properties of thermoplastic vulcanizate (TPV)/silica nanocomposites. The nanocomposites were prepared by the melt blending of TPV and maleic anhydride grafted polypropylene (mPP) into organically modified SiO 2 (m‐SiO 2 ), treated with n ‐hexadecyl…
Organoclays with thiol functionalities pending in the interlayer space were prepared by a single-template sol−gel synthesis. With magnesium nitrate, aluminum acetylacetonate, and mercaptopropyltrimethoxysilane involved, the reaction was established at room temperature. Characterizations were carried out using X-ray di…
We investigate the local proton dynamics in the proton conducting hydrated perovskite system $\mathrm{Ba}{\mathrm{In}}_{x}{\mathrm{Zr}}_{1\ensuremath{-}x}{\mathrm{O}}_{3\ensuremath{-}x∕2}\phantom{\rule{0.3em}{0ex}}(x=0.25\text{--}0.75)$ using infrared spectroscopy and first-principles calculations. We show that oxygen…
Abstract A series of La 0.6 Sr 0.4 Co 0.4 Fe 0.6 O 3‐δ (LSCF) perovskite‐type oxides were synthesized using a modified citrate process under various pH conditions (pH =1, 3, 5, 7, and 9, respectively). The effect of pH on the chelate process, crystal development, morphology, and oxygen permeability of LSCF oxides were…
We present a phenomenological theory of the uniaxial and biaxial nematic phases recently observed in bent-core mesogenic systems. To take into account the molecular anisotropy we introduce two types of symmetry transformation: "external" rotations which turn the molecules with respect to the laboratory axes and "inter…