Materials Literature
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Polycarbosilane/siloxane hybrid polymers were synthesized by sol−gel processing of the cyclic organosilicon compound 1,1,3,3-tetraethoxy-1,3-disilacyclobutane (CBS) and the linear polymer poly(diethoxysilylenemethylene) (L-EPCS) derived from CBS by ring-opening polymerization. The structure of these polymers and their…
The growth and decay processes of the optically induced birefringence in an azobenzene-functionalized polymer, DR19FPOZ (full name given in the text), and in another azobenzene guest/host polymer system have been studied. The temperature dependence of the birefringence signal is studied, and possible mechanisms associ…
Liquid metal induced embrittlement (LMIE) refers to the loss of ductility of normally ductile metals and alloys when stressed while in contact with a liquid metal. Various models have been proposed to describe the mechanisms by which LMIE failure takes place. In the present study the most promising of these are discus…
Abstract Nylon-6 and acrylate rubber (ACM) were melt blended in a Brabender Plasticorder at 220 °C and 40 rpm rotor speed. The reactive nature of the blend is reflected in the mixing torque behavior of the blends at different compositions. The solubility characteristics of the blends in formic acid solution gives an a…
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The carbothermal nitridation synthesis of α‐Si 3 N 4 is studied using electron microscopy techniques(FEG/SEM and TEM) and chemical composition analysis to characterize the reaction at various degrees of conversion. The reaction follows a nucleation‐growth mechanism. Without “seed”α‐Si 3 N 4 in the precursor, the react…
Six N-substituted derivatives of 2-methyl-4-nitroaniline (MNA) and two N-substituted derivatives of 4-nitroaniline were synthesized and their physical and optical properties were examined in the search for nonlinear optical materials with a sufficiently large second harmonic (SH) activity and applicability to practica…
A comprehensive model for solid-state polymerization of poly(ethylene terephthalate) was developed from analyzing the similarities and the differences between solid-state and melt polymerization. Considering the end groups diffusion limitation and the modification of concentrations of end groups and byproducts in the…
Previous molecular dynamics simulations have shown that the diffusion of a penetrant in a glassy polymer involves occasional jumps between cavities through the opening of a “neck”, and thus, because this is a rare event, the diffusion coefficient can be estimated using transition-state theory. We treat this process as…
Oxidation of lower molecular weight carboxylic acids such as formic, acetic, glyoxalic, and oxalic acids is often the rate-controlling step during wet oxidation (WO) of an aqueous waste stream exhibiting very high chemical oxygen demand (COD). The kinetics of WO of formic acid was studied in the absence and presence o…
Congenital and acquired diseases of the heart valves and great arteries are leading causes of morbidity and mortality. Current prosthetic or bioprosthetic replacement devices are imperfect and subject patients to one or more ongoing risks including thrombosis, limited durability, increased susceptibility to infection,…
Abstract— Ordinary ceramic refractories are used as lining material for industrial pyro‐processes. A high resistance to mechanical failure from an imposed strain or thermal shock is usually termed “flexibility”. A scientific approach to enhance this property is hindered by the fact that there is a lack of understandin…
The formation of cesium−gold alloys by the deposition of cesium on to a Au(100) surface has been investigated by both core-level (X-ray induced) and valence-level (He(II) radiation) spectroscopies. The stoichiometries of the alloy overlayer indicate the preferential segregation of cesium to the surface of the thinner…
We discuss a new method to estimate the absorption coefficient, the index of refraction, and the thickness of thin films using optical transmission data only. To solve the problem we used a pointwise constrained optimization approach, defining a nonlinear programming problem, the unknowns of which are the coefficients…
This work concerns the detection of incipient cavitation in pumps using acoustic emission (AE). Three activities have been pursued in this context: (a) the construction of a small-scale rig for the investigation of cavitation detection using AE sensors; (b) the acquisition of data on a 75 kW single-stage centrifugal p…
A method has been developed to quantitatively determine the composition of d-lactide and meso-lactide stereoisomer impurities in poly(lactide) containing predominantly l-lactide. In this method, the stereosequence information obtained from a few well-resolved resonances in the (1)H NMR spectrum representing RR and R s…
The catalytic activity of acid-treated clays for reactions involving polar substrates is optimized when the acidity of the surface and the swelling ability of the catalyst are at a maximum. In contrast the activity for reactions using nonpolar substrates is best when the surface area is maximized and the catalyst pres…
Langmuir−Blodgett films of copper(II) [tetrakis((3,3-dimethylbutoxy)carbonyl)]phthalocyanine and copper(II) [tetrakis( n -butoxycarbonyl)]phthalocyanine have been studied as sensitive elements of gas sensors. Moreover, alternate LB films of the two compounds and LB films obtained from a 1:1 mixture of them have also b…
The pinch-off of a drop of viscous fluid is observed using high-speed digital imaging. The behavior seen by previous authors is observed here; namely, the filament that attaches the drop to the orifice evolves into a primary thread attached to a much thinner, secondary thread by a slight bulge. Here, we observe that t…
Corrosion of steel in carbon dioxide (CO2)-containing solutions is considered a chemical reaction-controlled process. A corrosion rate equation was derived on the basis of fundamental reaction rate theory and compared to empirically determined relationships reported in the literature. The predictive equation was devel…