Materials Literature
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It is demonstrated from an i.r. study of the adsorption of formic acid on a Co/SiO2 catalyst that the adsorbates on the SiO2 surface and on the cobalt metal clusters are respectively a physically bonded HCOOH molecule and a formate species. The former species is easily desorbed but the latter remains stable at least u…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSeparation of p-cresol from its mixture with 2,6-xylenol by adductive crystallizationVivek K. Jadhav, Madhav R. Chivate, and Narayan S. TavareCite this: J. Chem. Eng. Data 1991, 36, 2, 249–251Publication Date (Print):April 1, 1991Publication History Published online1 May 200…
Abstract Advanced composites, specifically carbon‐fiber‐reinforced epoxies, are used extensively for a variety of demanding structural applications, primarily because of their high strength‐to‐weight and stiffness‐to‐weight ratios, corrosion resistance, and damage tolerance characteristics. Electron beam (EB) treatmen…
Abstract This study examines for the first time how matrix crosslinking affects the composite physical and mechanical properties of a graphite fiber reinforced PMR polyimide composite during long‐term isothermal aging. Unidirectional composite specimens of Celion 6000/PMR‐P1 were isothermally exposed at 288°C in air f…
An overview of high-temperature gas-cooled reactor (HTR) fission product chemistry and its influence on source terms in core heatup accidents is given. These accidents are risk-dominating for medium-sized HTRs and are characterized by maximum core temperatures of ∼2500°C (2773 K) and a late-starting, slowly proceeding…
Microwave dielectric parameters are measured for lithium-zinc ferrites with chemical formula Li0.5−x/2Fe2.5−x/2ZnxO4 (x=0.0, 0.1, 0.3, 0.5, 0.6). All the samples except x=0.5, show an increase in the dielectric loss with temperature. A relaxation-type mechanism is observed for x=0.5. The results are compared with the…
4-n-Alkyl-4′-cyanobiphenyls (1) have achieved widespread application as stable thermotropic liquid crystals with mesophases at room temperature. The importance of the cyano functional group in the liquid-crystalline behaviour of these compounds is not clearly defined. By modifying this functional group with minimal ch…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, characterization, and rubber elasticity of end-linked poly(tetrahydrofuran) elastomerLei Jong and R. S. SteinCite this: Macromolecules 1991, 24, 9, 2323–2329Publication Date (Print):April 29, 1991Publication History Published online1 May 2002Published inissue 29 A…
Abstract The plate method was used to measure the surface tension of different epoxy prepolymers and different hardeners. The values are correlated to the chemical structure. The effect of molecular weight is very weak for diglycidyl ether of bisphenol A (DGEBA) prepolymers. For α,ω‐diamino‐terminated poly(propylene o…
Regions of incomplete charge collection, or dead layers, are compared for Si(Li) detectors fabricated with Au and Pd entrance-window electrodes. The dead layers were measured by characterizing the detector spectral response to X-ray energies above and below the Si K alpha absorption edge. It was found that Si(Li) dete…
A new data-acquisition and display system has been developed for magnetic domain observation using spin-polarized scanning electron microscopy. The system is composed of 32 frame memories (512×512×16 bit), an image processor with two high-speed digital signal processors, and a 1280×1024 pixel color monitor. It has the…
Chitosan has been reductively N-alkylated with a 6-O-substituted galactose derivative bearing an iminodiacetate residue, to give a chitosan derivative having a hydrophilic branch and a metal chelating group. The Cu(II) binding capacity of the derivative was comparable to native chitosan, but showed better ion-exchange…
Article Cross Sections for the 100 MeV Proton-Induced Nuclear Reactions and Yields of some Radionuclides Used in Nuclear Medicine was published on April 1, 1991 in the journal Radiochimica Acta (volume 54, issue 2).
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCharacterization of hydrolytically degradable amino acid containing poly(anhydride-co-imides)Andrea Staubli, Edith Mathiowitz, Melissa Lucarelli, and Robert LangerCite this: Macromolecules 1991, 24, 9, 2283–2290Publication Date (Print):April 29, 1991Publication History Publi…
Abstract The dependences of phase structure and notch impact strength on conditions of mixing have been compared for the binary blend PP/EPDM and for two ternary blends PP/EPDM/PE possessing different viscosities of polyethylene. At low rates and short times of mixing a phase structure with pronounced inhomogeneities…
Thermal expansion was measured in two crystals of blue bronze (${\mathrm{K}}_{0.3}$${\mathrm{MoO}}_{3}$). At the Peierls temperature, the expansion coefficients exhibited a small steplike decrease along the chain direction, a nearly negligible change perpendicular to the cleavage planes, and a large steplike increase…
The passive film on a zinc electrode is often assumed to be composed of . Since removal of the electrode from the solution could alter the film composition, an in situ measurement technique is required for a qualitative analysis. We have developed a model to simulate the kinetics of anodic dissolution and passivation…
Abstract A new vertical microfurnace‐type pyrolyzer for thermal desorption and/or pyrolysis‐gas chromatography has been developed. The pyrolyzer consists of two independent temperature‐controlled ovens. Initially, in the desorption process, a sample cup containing the polymeric sample of interest is inserted into an o…
The acyl cyanides 1a — d are prepared from the corresponding acyl chlorides. The Paternó‐Büchi reaction of 1a — f with furan ( 2 ) yields the bicyclic oxetanes 3a — f with an endo / exo ratio varying from 3.5: 1 ( 1a ) to 16: 1 (1 d ). However, in the reaction of the chiral acyl cyanides 1b and 1c , a low chiral induc…
Abstract Elastomeric polymer consisting of poly(oxytetramethylene) segments and viologen units (PTV) was synthesized by the reaction of dicationic living poly(tetrahydrofuran) with 4,4′‐bipyridine at −70°C. The chloride or bromide ion was introduced as the counter anion into the viologen groups of PTV by the treatment…