Materials Literature
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The effect of new additives on the thermal conversion of a range of polyamic acids to polyimides at temperatures lower than 100°C was investigated using infrared spectroscopy. Additives such as m-hydroxybenzoic acid, p-hydroxyphenylacetic acid, and p-hydroxybenzenesulfonic acid were found to be highly effective as cur…
The thermal decomposition of Fe(CO)5, Cr(CO)6, Mo(CO)6, and W(CO)6 on Ni(100) surfaces and under ultrahigh vacuum conditions was studied by using temperature programmed desorption and x-ray photoelectron spectroscopies. The initial adsorption of those metal carbonyls is mostly molecular at low temperatures, but comple…
This work extends the results of previous workers on the influence of drawing on the crystallinity of PEEK and PEK to test temperatures well above Tg and to strain rates up to 103 s−1. The study thus includes measurement of crystallinity in samples tested in the strain rate regime where large increases in flow stress…
A range of substituted ferrocenes has been synthesized and studied for flame retardancy and smoke suppression on incorporation into plasticized PVC at 0.1–5.0 phr. Smoke suppression by up to 50 and enhancement of the limiting oxygen index by up to 4 units were observed. The differences in performance could not be corr…
In a recent Letter to the Editor (1995 Pure Appl. Opt. 4 1 - 5), the differential formalism of Chandezon et al (the C method) was extended to treat layered gratings in which the profiles of the medium interfaces within the same grating are different from each other. Numerical experiments have shown that a computer pro…
The ‘‘hyperfine magnetic field’’- Hhpf at the nuclei of the diamagnetic atoms 119Sn was measured in Heusler alloy Ni2MnSn by Mössbauer absorption spectroscopy for pressures up to 10.8 GPa at room temperature. The pressure dependences of HhpfSn does not show hysteresis and can be fitted by a linear function HhpfSn(P)/H…
The polymerization of isobutylene and styrene was studied using the 2-chloro-2,4,4-trimethylpentane/TiCl4 initiating system in the presence of a proton trap in halogenated hydrocarbons as solvents at −80°C. The polymerization of isobutylene was found to be living, and both homopolymers were soluble in n-butyl chloride…
Abstract Differences in processability between linear low denisty polyethylene (LLDPE) and low density polyethylene (LDPE) as well as for their blends subjected to extensional flow were assessed in terms of melt strength and elastic parameters from shear flow such as storage modulus (G′), and first normal stress diffe…
The thermal conductivities of two lithium aluminosilicate glass‐ceramic matrix composites reinforced with 30 vol% of either SiC VS (rice hull) whiskers or SiC VLS (vapor‐liquid‐solid) whiskers were determined from room temperature to 500°C. Because of the preferred alignment of the whiskers, the thermal conductivity v…
Traditional algorithms for evaluation of electrostatic forces in molecular dynamics simulations of proteins require computational work of the order O(N 2) for a system of N atoms. Truncation methods, which try to avoid that effort, entail intolerably large errors in forces, energies and other observables. Hierarchical…
The crystal structure of La 1− x Sr x CoO 3−δ (0≤ x ≤0.6) has been studied, using powder X-Ray diffraction. The crystal structure shows a transition from rhombohedral distorted perovskite for LaCoO 3−δ into cubic perovskite for La 0.4 Sr 0.6 CoO 3−δ . The cubic unit cell parameter is a c =3.8342(1) Å for La 0.4 Sr 0.6…
Abstract Mooney viscosities and thixotropic behavior have been determined for SBR melts containing carbon black and/or ground vulcanizate particles. A composition containing ambiently ground rubber has a higher viscosity than one with cryogenically ground rubber. This is attributed to occlusion of continuum rubber wit…
An approach to plotting hysteresis curves of soft magnetic materials using a personal computer assisted measuring system is presented. The resulting hysteresis curves provide enough detail to allow determination of the parameters required for a simulation with PSPICE (Jiles-Atherton model) or the Hodgdon/Carpenter mod…
Thin films of CdSe were deposited by a chemical bath technique from citratocadmium(II) or tartratocadmium(II) complex ions and N,N-dimethylselenourea. The final thicknesses of the films were from the citrate bath and from the tartrate bath, when the depositions were made at room temperature. The films are uniform and…
The plasma characteristics of a new arc mode on carbon referred to as the ‘‘stationary cathodic arc’’ are reported. Particularly, optical emission spectroscopy, probe and ion energy distribution measurements are used to compare the properties of the stationary arc with the normal ‘‘random cathodic arc’’ on carbon. The…
For near-α titanium alloys IMI 834 and TIMETAL 1100 oxidation behaviour was investigated as a function of microstructure. Isothermal thermogravimetry was performed at 750°C for 100 h in air. The morphologies and compositions of the scales produced were examined using scaninng and analytical electron microscopy and X-r…
Eight-coordination and identical ligand environments have been unequivocally established in the pair of stable iron(II) and iron(III) complexes shown on the right. The synthesis, structures and electrochemical properties of these iron complexes are presented here, together with some Mössbauer spectroscopic data on the…
Abstract A previously developed mathematical wetting model is generalized and applied to the following two closely related situations: the spreading of a liquid over a prewet solid surface and the receding contact‐line motion with a microscopic residual film, remaining behind the contact line. An analytical expression…
Abstract Here we report on investigations that have revealed for the first time that the Cs + ion templates the same metal germanium sulfide open‐framework as (CH 3 ) 4 N + (TMA + ), and that metal complexing agents enhance crystal size by at least two orders of magnitude. The synthesis, structures and thermal propert…
In our studies of the stability constants of metal complexes, we have investigated a number of macrocyclic ligands with pendant donor groups. The ligands are characterized by the fact that they have nitrogen donors in the macrocyclic ring and oxygen or sulfur donors in the pendant arms. These ligands represent seven d…