Materials Literature
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Abstract Anionic ring‐opening polymerization of propylene oxide in the presence of a potassium alkoxide initiator was accelerated by the addition of the bulky phosphonium salts tetrakis[cyclohexyl(methyl)amino]phosphonium‐, tetrakis[propyl(methyl)amino]phosphonium‐, and tetrakis[octyl(methyl)amino]phosphonium‐tetraflu…
The existence of a stable periodic time-dependent solution of Landau-Ginzburg–type dynamics of a sheared system is first shown by the simulations. By means of density-functional simulations we have shown that a spherical micellar phase of block copolymers is not destroyed by shear below a certain level, but forms elon…
ABSTRACT This article describes the development of a comprehensive procedure for broader application of the General Method in calculating thermal processes. In addition to the capability of calculating lethality (or process time to achieve a specified lethality) for a given set of heat‐penetration data, the procedure…
The accurate thermoviscoelastic characterization of a solid propellant is critical for optimum design of grains for high-performance solid motors for space applications. A more realistic experimental method is reported for the characterization of propellants at multiaxial stress conditions using a grain-pressurization…
Main chain discotic liquid crystalline polymers consisting of triphenylene-based units and alkyl spacers (C8, C10 and C12), connected by ester linkages in the 3- and 6-positions of triphenylene, have been synthesized and their mesomorphic properties were studied by DSC, polarizing optical microscopy and X-ray diffract…
Wood has been treated with amino resins and amino resins modified with phosphoric acid to impart flame retardancy. The thermal degradation of samples has been studied by differential thermal analysis (DTA) and thermogravimetry (TG) in air. From the resulting data, kinetic parameters for different stages of thermal deg…
This article describes an experimental setup designed to measure the electrical conductivity of molten and viscous oxides from 1200 to 400 °C. The “4-electrode” method was adapted to perform impedance measurements over wide temperature and frequency ranges. High-frequency electrode effects were calculated and eliminat…
ADVERTISEMENT RETURN TO ISSUEPREVFeaturesNEXTPeer Reviewed: Responsive Drug Delivery SystemsApplying micromachining, biosensors, telemetry, and other techniques at the interface of analytical chemistry and bioengineering to revolutionize drug delivery.Sapna K. Deo, Elissavet A. Moschou, Serban F. Peteu, Leonidas G. Ba…
A method is proposed for analytical approximation of the Preisach distribution function. The Preisach functions of several materials are determined from measured Everett integrals and the features of parameter determination by mean square error minimization over the major or a symmetrical minor loop investigated. The…
In this paper certain aspects of the dynamic behavior of a multilayered, composite plate with shape memory alloys (SMA) wires have been investigated. The influence of parameters such as the orientation and location of SMA wires, the orientation and relative volume fraction of reinforcing fibers, the thickness-to-lengt…
The stability of magnetic domain structures of small grains of magnetite were examined between room temperature and the Curie temperature using a high‐resolution three‐dimensional micromagnetic algorithm. At all times the minimum resolution used was determined by calculating the exchange length. Using an unconstrained…
The formation of porous Si (PSi) antireflection coating (ARC) on n+–p multicrystalline Si solar cells has been investigated in view of its implementation at the last stage of the solar cell processing. PSi layers were formed either by electrochemical (EC) etching or by chemical stain (CS) etching and led to effective…
A method is proposed for fabric 3D surface reconstruction using a photometric stereo method. As an investigation of the efficacy of the method, the 3D surface of an AATCC standard wrinkle pattern is reconstructed and its wrinkle degree is measured using four index values that indicate the variation of the surface heig…
A bicrystal of Zn with an originally flat 89° 〈101̄0〉 symmetric tilt boundary was annealed in a magnetic field of 25 T. The boundary migrated under the action of a magnetic driving force in the direction of the grain with higher diamagnetic susceptibility. In addition, the boundary changed its crystallographic orienta…
We demonstrate the use of a photoelectron emission microscope in connection with a retarding field electron energy analyzer for the fast acquisition of two-dimensional momentum resolved photoelectron angular distribution patterns. This opens the possibility to combine spatial, momentum, and energy resolution of photoe…
Raman scattering measurements have been made on SiC ceramics prepared from two powdered by sintering at different temperatures. The Raman spectra of starting powders have also been measured. The volume contents of the 4H and 15R polytype phases relative to that of the 6H phase in the ceramics are inferred from the Ram…
This paper describes the relation between the flow resistance of a textile material and its geometry. A literature survey reveals that the orifice model is most suited to modeling the flow resistance of woven fabrics, but applications of this model were, until now, restricted to relatively open fabrics due to the geom…
A new series of chiral liquid crystalline materials having the same rigid core containing a keto group, and various numbers of (S)-lactate groups in the chiral segment, has been synthesized and studied. All the compounds contain a branched terminal alkyl chain derived from (S)-2-methylbutanol. The influence of the num…
The possibility of developing fine‐grained (∼0.5–3 μm) and dense (≥0.98ρ th ) alumina (90 vol%)–aluminum titanate (10 vol%) composites with improved thermal shock resistance and maintained strength is investigated. One alumina material and one composite with similar microstructures (porosity and grain‐size distributio…
The stabilities of porous silicon samples after thermal oxidation, thermal carbonization, thermal nitridation and dodecene-treatment have been compared. The stability of these samples in different temperatures and RH-atmospheres was examined by measuring the weight increase as a function of time. Also, the reactivity…