Materials Literature
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We describe experiments devised to detect a possible effect of annealing on the vibrational density of states (DOS) in a glassforming polymer with high accuracy from inelastic incoherent neutron scattering. Such an effect could be expected from the argument that annealing changes the behavior of many measured quantiti…
Tussah silk fibers were graft-copolymerized with methacrylamide (MAA) and 2-hydroxyethyl methacrylate (HEMA) in aqueous media, using a chemical redox system as an initiator. High weight gain values were obtained with both grafting agents (up to 175%). The extent of homopolymerization was negligible for the MAA graftin…
Polyurethane (PU) anionomers were prepared as aqueous dispersions and as solutions in tetrahydrofuran or absolute ethanol using dimethylol propionic acid (DMPA) as the stabilizing moiety, isophorone diisocyanate, polytetrahydrofuran, and cyclohexane dimethanol. The structure–property relationships were investigated fo…
Direct measurements of the dynamics of photoinduced electrons in AgI, AgI/Ag2S, and AgBr/Ag2S semiconductor colloidal nanoparticles have been performed using femtosecond pump–probe laser spectroscopy. In AgI the transient absorption signal features a laser pulsewidth limited rise followed by a double exponential decay…
The influence of the molecular weight of poly(2,6-dimethylphenylene oxide) (PPO) on the flame retardancy of ethylene–propylene–diene-modified elastomer (EPDM) formulations containing melamine, kaolin, and PPO formulations was studied. The influence of the molecular structures of various char-forming polymers on their…
A systematic model is presented for a free expansion polymer foaming process that includes simultaneous nucleation and bubble growth. An influence volume approach, which couples nucleation and bubble growth, is used to account for the limited supply of dissolved gas. The melt rheology is described using the Larson vis…
We have performed electronic structure calculations of the interaction of potassium and oxygen with graphite (GR), individually and as coadsorbates. We use up to three graphite planes to represent the graphite surface, but we show that the main physics is correctly described by a single graphite layer. At low coverage…
The density of 0.5–3 μm thick vapor-deposited films of water ice were measured by combined optical interferometry and microbalance techniques during deposition on an optically flat gold substrate from a capillary array gas source. The films were of high optical quality with an index of refraction of 1.29±0.01 at 435.8…
Spatiotemporal fluctuations of the local structure in liquid water are studied with the molecular-dynamics simulation. At temperatures around and above the melting point, each molecule alternately goes through the structured period and the destructured period. Lifetime of each period spreads from several hundred fs to…
Soda-lime glass samples have been subjected to both single and double field reversals during electric field assisted - ion exchanges in the temperature range 350-450 C. Changes in refractive index profiles, chemical profiles and surface stress were observed during the exchanges and a comparison has been made with prev…
The low-frequency behaviour of the isotropic elastic modulus and mechanical loss tangent of modified lead titanate ferro-piezoelectric ceramics have been studied by the three-point bending technique. Measurements of these parameters as a function of the temperature were performed in the frequency range of 0.2 to 20 Hz…
This paper presents an experimental study of the coordination number of binary packings by the use of the liquid bridge technique and provides detailed information about the distributed coordination numbers corresponding to different types of contacts between small and large components and their dependence on particle…
The reactions of ethanol and 1-propanol on a 1.3 monolayer Co overlayer was investigated in an effort to understand the reactivity of Co thin films deposited on Mo(110). Electron energy loss data show that O−H bond scission to afford the alkoxide occurs by 275 K for both alcohols on a Co monolayer deposited on Mo(110)…
Four generations of a dendrimer with a fluorescent core consisting of a rubicene moiety are synthesized. The biexponential nature of fluorescence decay in toluene indicates the presence of two emitting conformations. Molecular modeling suggests that a conformation where the dendrons interact with the core is not impro…
Radiolysis of aqueous solutions of TNT was examined to provide fundamental information concerning the reactions of TNT with radical species in water. γ-Radiation was used in conjunction with radical scavengers to compare yields for radiation-induced TNT transformation under oxidizing and reducing conditions and in the…
The gas-phase hydrogenation of acetonitrile was studied with silica-supported platinum catalysts of which the degrees of metal dispersion were widely changed by reduction conditions. The activities were found to decrease gradually during the course of reaction for all the catalysts examined. The initial rate of reacti…
Buried channel optical waveguides were fabricated from fluorinated polyimides. They operated in single mode and showed an optical loss of less than 0.3 and 0.7 dB/cm for TE and TM polarizations, respectively, at a wavelength of 1.3 mum. Moreover, these waveguides had high heat and moisture resistance; the optical loss…
A conformational energy model has been set up for poly(ethylene terephthalate) (PET) for use in molecular dynamics simulations. The molecular dimensions, as expressed by the characteristic ratio, and the dipolar correlation factor of PET are key parameters in the simulations because they depend very differently on the…
The formation of iron oxide films and their roles in determining the dry wear properties of low alloy steel couples are described. Essentially, alpha-Fe<SUB>2</SUB>O<SUB>3</SUB>, haematites (Fe<SUB>3</SUB>O<SUB>4</SUB>), wustite (FeO) and oxide mixtures were the predominant compositions found in four regions of mild o…
Lead is one of the poisonous elements for de-NO x catalysts especially in the case of municipal waste incineration plants. Samples of a commercial selective catalytic reduction catalyst were impregnated with different amounts of Pb(NO 3 ) 2, and their catalytic activities were studied. The XPS and SEM analysis showed…