Materials Literature
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Abstract Imidization of the precursor of a liquid crystalline polyimide was investigated using modulated differential scanning calorimetry (MDSC), Fourier transform infrared (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), and thermogravimetric analyzer (TGA) coupled to FTIR (TG‐IR). The FTIR study reveale…
The role played by a glass substrate on the accurate determination of the optical constants and the thickness of a thin dielectric film deposited on it, when well-known envelope methods are used, is discussed. Analytical expressions for the two envelopes of the optical transmission spectra corresponding to film. with…
Most of our resources, especially materials, are treated by economics as if the supply were infinite, when demonstrably it is not for those that are non-renewable. In his engineering, use of materials and energy, man lets design takes second place, whereas nature treats materials as expensive and designs with apparent…
Abstract Depolymerisation reaction of polyester waste was carried out by a saponification reaction. Yields of depolymerised products were up to 85% for a 2.5‐h reaction time. Products obtained were characterized by chemical as well as instrumental analysis such as mp (sublimation), acid value and FTIR spectra. The val…
Abstract A series of blends of polypropylene (PP)–polyamide‐6 (PA6) with either reactive polyethylene–octene elastomer (POE) grafted with maleic anhydride (POE‐ g ‐MA) or with maleated PP (PP‐ g ‐MA) as compatibilizers were prepared. The microstructures and mechanical properties of the blends were investigated by mean…
Abstract The preparation of polyamide‐6/clay, high‐density polyethylene/clay, and high‐density polyethylene/ polyamide‐6/clay nanocomposites is considered. X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier Transform Infrared (FTIR) measurements show that the clay enhances the crystallizatio…
To understand chirality in cholesteric (Ch) liquid crystals, we performed an experimental study on the Ch-smetic A (SmA) transition of a cholesteric liquid crystal. By studying the reflection spectrum at zero field and at the critical electric field used to unwind the helical structure, we were able to measure the hel…
A series of isotactic polypropylene (PP) samples with poly(ethylene- co -propylene) long chain branching were produced by a semibatch copolymerization of poly(ethylene- co -propylene) macromonomer (EPR), prepared in a high-temperature continuous stirred tank reactor (CSTR), and propylene using rac -dimethylsilylenebis…
Nanocrystalline ZnS thin films were synthesized by chemical vapor deposition (CVD) using Zn(O-iPrXan) 2 [O-iPrXan=S2COCH(CH3) 2] as a single-source precursor compound. The coatings were deposited on silica substrates in N2 atmosphere at temperatures between 200 and 450 °C and subsequently characterized by glancing-inc…
The sintering and electrical characteristics of La‐modified Na 1/2 Bi 1/2 TiO 3 (NBT) was investigated from a defect structure viewpoint. To reveal the role of cation vacancies, two series of ceramics, with different cation vacancies, were processed to compensate the excess positive charge of lanthanum ions. In a regi…
Abstract Understanding the mechanisms of growth and inhibition during crystallization of calcium sulfate is of primary importance for many industrial applications. For instance, inhibition of the crystallization process may be required to prevent scale formation in pipes, boilers, heat exchangers, reactors, reverse os…
We present a microspectrometer based on a tunable interference filter for infrared or visible light that scans the desired part of the spectrum within milliseconds. A single pixel detector measures serially the intensity at selected wavelengths. This concept avoids expensive linear detectors as used for grating spectr…
Abstract Titanium dioxide films have been deposited using DC magnetron sputtering technique. Films were deposited onto RCA cleaned p‐silicon substrates at the ambient temperature at an oxygen partial pressure of 7 × 10 –5 mbar and sputtering pressure of 1 × 10 –3 mbar. The deposited films were annealed in the temperat…
Bisphenol-A (BPA), a known endocrine disruptor, is a main building block of epoxy resin which has been widely used as a surface coating agent on residential water storage tanks. Therefore, BPA leaching from the epoxy resin can adversely affect human health. In this study, BPA leaching from three epoxy resins were quan…
Clustering of rare-earth dopants in GeAs sulfide glasses was studied by fluorescence spectroscopy of Pr-doped glasses and by EPR measurements of Gd-doped samples. The linewidth of the g ∼ 2 resonance of Gd 3+ , as well as the relative intensity of emission from the 1 D 2 level of Pr 3+ , was used as a relative measure…
Praseodymium‐doped ceria (CeO 2 ) nanopowders have been synthesized via a simple but effective carbonate‐coprecipitation method, using nitrates as the starting salts and ammonium carbonate as the precipitant. The precursors produced in this work are ammonium rare‐earth double carbonates, with a general formula of (NH…
The relaxivity and bioreduction rates of eight dendrimer-linked nitroxides varying in the number of nitroxides per molecule were measured and the potential use of these compounds as MR contrast agents was demonstrated. The T(1) and T(2) relaxivities, measured at room temperature and 1.5 T, varied linearly with the num…
An unstructured finite volume scheme is applied to the solution of sub-micron heat conduction problems. The phonon Boltzmann transport equation (BTE) in the relaxation time approximation is considered. The similarity between the radiative transfer equation (RTE) and the BTE is exploited in developing a finite volume s…
Summary The concept of ferrolysis as defined in the 1970s by Brinkman and co‐workers is mentioned in the recent literature as a dominant process to explain clay disintegration, interlayering of clay minerals, and strong texture contrast of duplex soils, in which bleaching and mottling are predominant features. Ferroly…
Zigzag-type carbon nanotubes have been selectively produced by surface decomposition of a well-polished SiC single crystal . The SiC wafer was heated to 1500 °C at a very small heating rate under vacuum. Transmission electron microscopy (TEM) and electron diffraction patterns revealed that almost all the well-aligned…