Materials Literature
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A modified method for obtaining large quantities of exfoliated single layers of WS2 is reported. The restacked WS2 obtained from the precipitation of the single layers is metastable with respect to 2H-WS2 with an apparent activation energy of 82.4 kJ/mol, and a conversion temperature of 207 °C at 5 °C/min. Pressed pel…
Abstract The reinforcing effect of cellulose microcrystals, or whiskers, dispersed in a thermoplastic matrix is analyzed. In Part I [ Polym. Compos. , 17, 604 (1996)], the preparation and the characterization of cellulose whiskers obtained from wheat straw were detailed. Composite films were processed by freeze‐drying…
Electrolytes based on 1‐ethyl‐3‐methylimidazolium cation ( EMI + ) and either the hexafluorophosphate ( EMIPF 6 ) or tetrafluorborate ( EMIBF 4 ) anion in organic alkyl carbonate solvents have been evaluated for use in electrochemical capacitors The conductivity capacitance, limiting oxidation and reduction potentials…
A high‐pressure sampling mass spectrometer was used to detect the volatile species formed from SiO 2 at temperatures between 1200° and 1400°C in a flowing water vapor/oxygen gas mixture at 1 bar total pressure. The primary vapor species identified was Si(OH) 4 . The fragment ion Si(OH) 3 + was observed in quantities 3…
Abstract The crystalline oxozirconium methacrylate clusters Zr 6 (O‐H) 4 O 4 (OMc) 12 and Zr 4 O 2 (OMc) 12 were obtained by reaction of Zr(O n Pr) 4 with an excess of methacrylic acid and analysed by X‐ray diffraction. The oxide and hydroxide groups are in a μ 3 ‐ bridging mode in both structures, and the methacrylat…
The use of the thermoelastic martensitic transformation and its reverse transformation has recently been proposed and demonstrated for several active control applications. However. the present constitutive models have lacked several important fundamental concepts that are essential for many of the proposed intelligent…
Abstract A review of recent developments in polypeptide synthesis is provided. This article is focused on development of new materials based on polypeptides rather than on reproduction or applications of natural protein‐based materials. Synthetic methods fall into two major categories: biological and chemical. The mos…
The thermal behaviour in nitrogen and in air of phenol-formaldehyde, m-cresol-formaldehyde and p-cresol-formaldehyde resins having different levels of crosslinking is reported. The steps of degradation are studied by FTIR analysis of the residues. The different structures and crosslinking levels induce different therm…
The thermal conductivity of dense, polycrystalline garnet ceramics with compositions of Y 3 Al x Fe (5−x) O 12 (x = 0.0, 0.7, 1.4, and 5.0) was measured in the temperature range 23° to 1000°C. The high‐temperature thermal conductivity of some of these garnets was found to be as low as 2.4 W·m ‐1 K ‐1 . The effects of…
In advance of a discussion on structural effects on biodegradation, aliphatic polyesters as biodegradable structural materials were classified into four types regarding chemical structure, that is poly(ω-hydroxy acid), poly(β-hydroxyalkanoate), poly(ω-hydroxyalkanoate) and poly(alkylene dicarboxylate), and reviewed on…
Abstract This paper thoroughly describes the decomposition procedure, using the example of DECOMPXR (Lanson 1990). The steps of the decomposition procedure are: 1) preliminary data processing; 2) decomposition; 3) validation of results; and 4) use of the results. The use of decomposition is restricted to the separatio…
High-resolution 500 MHz solution-state 1 H and 13 C NMR spectra of various poly(lactides) indicate at least hexad stereosequence sensitivity. The poly(lactides) were prepared in vials by melt polymerization of various combinations of l -lactide, d -lactide, and meso -lactide at 180 °C for 3 h using tin(II) bis(2-ethyl…
The Al 2 O 3 ZrO 2 Y 2 O 3 system was studied in the range of temperatures 1600°–2800°C by methods of X‐ray analysis at 20°C, petrography, DTA in He at temperatures to 2500°C, thermal analysis in air using a solar furnace at temperatures to 3000°C, and electron microprobe X‐ray analysis. The stable and metastable phas…
Ceramic lead magnesium niobate–lead titanate ((1‐x)PMN ‐x PT) of different compositions has been prepared by the columbite precursor method. This study discusses compositions ranging from 0.94PMN–0.06PT to 0.60PM–N0.40PT, focusing on two areas of the (1‐x)PMN x PT system: compositions that exhibit electrostrictive beh…
Cathodic polarization curves for the reduction of oxygen and protons on platinum and iron electrodes under thin electrolyte layers ( X f : 1 mm to 10 μm) were measured to elucidate the effects of the thickness and the pH of the electrolyte layer on the initial atmospheric corrosion stage of iron. A limiting current wa…
Polyaniline (PAn) was synthesized chemically and doped with various dopants, such as HCl, HCOOH, I2 and methylene blue (C16 H18 ClN3 S), by an immersion method. The structure of these samples was investigated by infrared (IR) spectroscopy and wide-angle X-ray diffraction (WAXD) analysis. Remarkable changes have been o…
In this paper, a newly developed polymer, shape memory polyurethane (SMP), will be introduced. The shape memory polymer possesses the same basic shape memory effect and elasticity memory effect as shape memory alloys. Shape memory polymers can change their elastic modulus up to 500 times around their glass transition…
A refined and generalized version of a previously suggested model of the silica surface, in which geminal silanols are situated on surface segments similar to (100)-type faces of the β-cristobalite structure and single silanols are situated on surface segments similar to corresponding (111)-type faces, is supported by…
Abstract The considerable progress made in the development of fundamental and applied aspects of sonoelectrochemistry, the coupling of power ultrasound into an electrochemical experiment, is reviewed with respect mainly to the measurement and analysis of effects observed in conventional sonoelectrochemical experiments…
Abstract A general kinetic treatment of the system with intermolecular chain transfer followed by fast reinitiation is given. It leads to the broadening of the molecular weight distribution (MWD), the number of growing chains being invariable. Thus, this system can be considered as a special case of living polymerizat…