Materials Literature
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Abstract The composites investigated in this article were epoxy resins reinforced with jute‐fibers. The jute‐fibers were modified with an epoxyfunctional‐γ‐glycidoxypropyltrimethoxy‐silane (A‐187 from Osi‐Specialtis GmbH, Germany), which works as a coupling agent between fiber and matrix. The introduction of the coupl…
The elastomeric behavior of low-crystallinity ethylene−octene copolymers prepared by Dow's INSITE constrained geometry catalyst technology is described. Deformation in uniaxial tension was examined as a function of comonomer content and molecular weight. Within the melting range of copolymers, temperature was used as…
Microelectrochemical studies for hydrogen storage materials have been carried out by using a microelectrode technique. A carbon fiber filament was contacted with single particles of , and in 1 M KOH solutions by using a micromanipulator, where Lm indicates the lanthanum‐rich rare‐earth metal. In this way, cyclic volta…
Acid−base properties of branched, weak polyelectrolytes are analyzed theoretically by means of Ising models with short-range interactions. Assuming that the structure of the branched polyelectrolyte can be approximated by the topology of a tree (no closed loops), the Ising model with nearest neighbor pair interactions…
X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and potentiodynamic measurements have been made on chromate conversion-coated Al 2024-T3 alloy. X-ray photoelectron spectroscopy measurements indicated that the conversion coating had a surface of CrOOH and Cr(VI), enriched in ferricyanide. The…
Microscopic features and their hysteretic behavior can be used to predict the macroscopic response of materials in dynamic experiments. Preisach modeling of hysteresis provides a refined procedure to obtain the stress–strain relation under arbitrary conditions, depending on the pressure history of the material. For hy…
Extracellular adhesives from the diatoms Achnanthes longipes, Amphora coffeaeformis, Cymbella cistula, and Cymbella mexicana were characterized by monosaccharide and methylation analysis, lectin-fluorescein isothiocyanate localization, and cytochemical staining. Polysaccharide was the major component of adhesives form…
Abstract The polymerization of lactides with various D / L enantiomeric compositions using achiral Schiff's base/aluminium methoxide as initiator (SALENAlOCH 3 ) in dichloromethane solution at 70°C is reported. The conversion was kept below 70% in order to limit transesterification reactions. The polymers obtained aft…
We have used electron tomography to characterize the self-assembly of nanostructures formed by rodcoil copolymers. The rodcoil copolymers used contained a perfectly monodisperse rod segment prepared by stepwise synthesis. The chemical compound rod segment is, in turn, covalently linked at one terminus to an end-functi…
The dielectric behavior of a solid solution, 10 mol % lead titanate in lead magnesium niobate, is measured at different frequencies from 100 Hz to 100 kHz in the temperature range from -100 to 120 \ifmmode^\circ\else\textdegree\fi{}C. A standardizing method is introduced to analyze the curve of the dielectric constant…
The macroscopic behavior of the contact line during the spontaneous spreading of a droplet can be described in terms of microscopic quantities, specifically the substrate−liquid and liquid−liquid interactions. Here, for the first time, the results of molecular dynamics simulations of very large sessile drop systems ar…
Monometallic and bimetallic colloids were prepared in micelles of the block copolymer polystyrene- b -poly-4-vinylpyridine in toluene and analyzed by electron microscopy and various techniques of X-ray analysis. These metal colloids were studied in hydrogenation of cyclohexene, 1,3-cyclooctadiene, and 1,3-cyclohexadie…
We have investigated the conjugated polymer poly(3,4-ethylenedioxythiophene) as electrode material in electrochemical supercapacitor. The conjugated polymer is prepared by chemical polymerization in the form of thin films on nonconducting plastic substrates. One film is electrochemically reduced to the neutral state,…
Aqueous solutions of α-cyclodextrin (α-CD) and polyethylene glycol (PEG) form interesting complexes, where several α-CD units are penetrated by the linear polymeric PEG chain and produce a so-called “polyrotaxane”. This supramolecular structure is stabilized by strong interactions between the α-CD hydrophobic internal…
The effect of Keggin heteropolyoxotungstates (XW 12 O 40 n - with X = H 2, P, Si, B or Co) on Langmuir films has been studied for monolayers of DODA (dimethyldioctadecylammonium) and DPPC (1,2-dipalmitoyl- sn -glycero-3-phosphorylcholine). Marked modifications of the compression isotherms have been observed when the K…
Three approaches for the synthesis of dendrimers with poly( p -phenylene)-PPP derived cores are described. The respective limitations of these approaches are assessed in view of the goal of this research: to make available structurally perfect, high molecular weight polymers with a dense sequence of sterically demandi…
Abstract A catalytic system consisting of sodium tungstate dihydrate, (aminomethyl)phosphonic acid, and methyltrioctylammonium hydrogensulfate, effects the epoxidation of olefins using 30% hydrogen peroxide with a substrate-to-catalyst molar ratio of 50—500. The reaction proceeds in high yield without solvents, or, al…
Size-dependent structural and dynamic properties of CdS nanocrystals with 13−120 Å diameter and of molecular crystals consisting of three-dimensional superlattices of these nanoparticles have been determined by extended X-ray absorption fine structure spectroscopy (EXAFS) at the Cd K edge at temperatures between 5 and…
The tensile creep behavior of two rare‐earth dopant systems, lanthanum‐ and yttrium‐doped alumina, are compared and contrasted in order to better understand the role of oversized, isovalent cation dopants in determining creep behavior. It was found that, despite some microstructural differences, these systems displaye…
The heterogeneity of urinary degradation products of C-terminal telopeptides derived from the alpha1 chain of human type I collagen was investigated and characterized. The urinary fragments characterized in this study consisted of two cross-linked (X) amino acid sequences derived from the C-terminal telopeptide (alpha…