Materials Literature
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The paper presents the results of ultrasonic and microwave dielectric investigations of the ferroelectric PbHPO4 in the vicinity of phase transition temperature. The largest anomaly of ultrasonic velocity and attenuation appears when ultrasonic wave propagates along the b-axis of the crystal. The ultrasonic velocity a…
A new approach to inhomogeneous layer synthesis is proposed that differs from the classical Fourier transform methods. This approach, based on the wave-number discretization of the continuous Q function, is described together with the relationship between the smoothness of the inhomogeneous layer’s refractive-index pr…
The reaction mechanisms and kinetics of endcapped ethynyl polyethers were studies in the temperature range 150-220C. The results obtained by ' 3 C and 'H NMR, FrTIR, HPLC and DSC indicate reactivity differences and competing reactions. These materials were cured and their thermal properties evaluated.
Dielectric, piezoelectric and pyroelectric response of selected compositions from this solid solution system have been investigated as a function of PT and BT content for compositions near the morphotropic phase boundary (PMT-PT). The dielectric constant and loss of poled samples were determined. Pyroelectric coeffici…
Single crystals of KBa 2 V 2 O 7 Cl were prepared by crystallization from flux. The transparent crystals crystallize with hexagonal symmetry, space group D 4 6h -P6 3 /mmc, a = 5.7688, c = 15.0762 Å. Z = 2. KBa 2 V 2 O 7 Cl is characterized by V 2 O 7 double tetrahedra and a statistical distribution of K + and Ba 2+ s…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA Mild and General Approach to the Preparation and Trapping of Highly Reactive FormylsilanesAlan R. Katritzky, Zhijun Yang, and Qingmei HongCite this: J. Org. Chem. 1994, 59, 17, 5097–5099Publication Date (Print):August 1, 1994Publication History Published online1 May 2002Pu…
Abstract The degradation of a branched perfluoropolyalkylether (PFPAE) fluid with anhydrous AlCl 3 , in the absence of oxygen, has been re‐examined with emphasis on understanding the nature of the volatile products formed. GC/FTIR and GC/MS have been employed for identification of a number of compounds in the complex…
In situ x-ray photoelectron spectroscopy has been used to analyze the nature and extent of damage to the Si(100) surfaces bombarded with xenon ions in the energy range 0.25–2 keV. Dramatic changes in the Si 2p core levels were found upon ion bombardment. A curve-fitting analysis of the core level shows that an amorpho…
Abstract A technique for anodic composite-plating was developed. By this technique, PTFE composite-plated hydrophobic β-PbO2 electrodes were prepared, and their electrochemical properties as anodes were preliminarily examined.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChain Conformations of Homopolymers Dissolved in a Microdomain of Diblock CopolymerYushu Matsushita, Naoya Torikai, Yasuhiro Mogi, Ichiro Noda, and Charles C. HanCite this: Macromolecules 1994, 27, 16, 4566–4569Publication Date (Print):August 1, 1994Publication History Publi…
Abstract Aromatic poly(ether‐ketone‐amide)s were prepared by the palladium‐catalyzed polycondensation of aromatic dibromides containing ether ketone units, aromatic diamines, and carbon monoxide. Polymerizations were carried out in N , N ‐dimethylacetamide (DMAc) in the presence of palladium catalyst, triphenylphosphi…
Abstract This paper reports a temperature‐programmed desorption mass spectrometry method for determining the nature, number and distribution, according to relative strength, of acid sites in solid catalysts. By using pyridine as the titrant, the overall, Brönsted (B) and Lewis (L) acidities are determined. The Brönste…
Flavocytochrome b2 from Saccharomyces cerevisiae acts physiologically as an L-lactate dehydrogenase. Although L-lactate is its primary substrate, the enzyme is also able to utilize a variety of other (S)-2-hydroxy acids. Structural studies and sequence comparisons with several related flavoenzymes have identified the…
Abstract A series of new poly(arylene ether phenyl‐s‐triazine)s was prepared by the nucleophilic aromatic substitution polymerization of the potassium salt of bisphenols with 2,4‐bis (halophenyl)‐6‐phenyl‐s‐triazine in N ‐methyl‐2‐pyrrolidone at elevated temperature. The polymers with inherent viscosities exceeding 0.…
We reexamine the problem of a nematic fluid trapped between two concentric cylinders with different anchoring conditions on each of the cylinders. If the splay constant ${\mathit{K}}_{\mathit{s}}$ is less than the bend constant ${\mathit{K}}_{\mathit{b}}$, the director varies monotonically between the plates. If, howe…
ADVERTISEMENT RETURN TO ISSUEPREVArticleRole of Entanglements on the Fracture Toughness of Incompatible Polymer InterfacesV. Janarthanan, Richard S. Stein, and Paul D. GarrettCite this: Macromolecules 1994, 27, 17, 4855–4858Publication Date (Print):August 1, 1994Publication History Published online1 May 2002Published…
We investigate the moiré fringe pattern of two concentric-circle gratings with the aim of measuring the relative two-dimensional planar displacement induced between the gratings. In the first stage we give a comprehensive mathematical approach for the analysis of fringe patterns. Then we suggest a fast computational m…
We present the first small angle neutron scattering studies on liquid crystal polymer composite systems, where small amounts of polymers are dispersed in liquid crystals. A recent study (A. Jákli, D. R. Kim, L. C. Chien and A. Saupe, 1992, Appl. Phys. 72, 3161) showed that even 1 wt% of polymer can induce phase separa…
Abstract In this paper, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD) were used to study the structure and compatibilization of poly(propylene) (PP)/nylon‐12 (PA 12) blends. The compatibilization of maleated PP(PP‐MA) and graft copolymer (PP‐MA‐ g ‐…
The chemical and physical properties of AgelessR oxygen absorber, a commercial oxygen scavenger, are described. The active ingredient in Ageless is finely divided iron, but the key to its use as a practical method of removing oxygen is the method of preparation, additives and packaging. Criteria for museum use are put…