Materials Literature
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The X-ray crystallography technique has greatly expanded in scope with the development and use of instrumentation at synchrotron sources, particularly in ‘large molecule’ protein crystallography and now also in ‘small molecule’ chemical crystallography. A variety of technical themes are described to illustrate this. S…
The change in the microphase separation transition (MST) temperature of a styrene−butadiene−styrene (SBS) triblock copolymer induced by the addition of polystyrene (PS) was investigated by small-angle X-ray scattering. It was found that the transition temperature was determined from the molecular weight ( M H ) of the…
The microscopic rotational dynamics of a main chain liquid crystalline (LC) poly(ether) in its nematic phase is studied in detail by nonlinear least squares analysis of ESR spectra in the slow motional regime. This complements results reported in an accompanying paper, which focuses on macroscopic translational diffus…
Three perylene tetracarboxylic bisimide chromophores have been attached to a benzene ring in m-position (3). In this way steric and through-bond interactions of the chromophores are minimized and their through-space-interactions can be studied for which an unusually high bathochromic shift has been found. This indicat…
Polyoxazolidones of different crosslink densities were prepared by reacting NCO-terminated oxazolidone quasi-prepolymers with diglycidyl ether of bisphenol A. The NCO-oxazolidone quasi-prepolymers were prepared at a 5/1 NCO/epoxy ratio, utilizing three different types of isocyanates: 4,4'-methylene bis(phenyl isocyana…
Commercial purity (CP) titanium is used primarily in applications requiring exceptional corrosion resistance. The CP titanium alloys contain small amounts of oxygen. The mechanical properties of titanium, such as tensile and fatigue strengths, can be enhanced with oxygen additions, but care must be taken not to compro…
Major thermal decomposition products from polyvinylidene chloride (PVDC) under two pyrolysis conditions (0% O2, and 10% O2) and several different heating rates were determined. Kinetic parameters for the evolution of the major degradation products for polyvinyl chloride (PVC) and PVDC were also determined. Results sho…
Abstract
A series of amine donor-substituted dicyanoquinodimethane molecules with large calculated hyperpolarizabilities has been investigated. Molecular and crystal structure details of a prototypical system are presented. Moderate to strong phase-matched powder second-harmonic generation is observed in chiral amine-substitut…
Abstract The thermal degradation of polyisobutylene is characterized by kinetics consisting of four types of intramolecular hydrogen abstraction (back‐biting) of primary (p) and tertiary (t) terminal macroradicals (R and R ) and the successive β scission at the inner position of the main chain. This reaction affords f…
Abstract The proton‐catalyzed polycondensation of aromatic aldehydes with aliphatic and aromatic α,ω‐dithiols leads to polymercaptals. The reaction may be carried out in bulk or solution. The bulk polycondensation was catalyzed by hexafluorophosphorous acid (HPF 6 ), formed photochemically by irradiation of the sample…
IR spectra are reported of Cr(CO)6, (C6H6)Cr(CO)3 and (Me4C6H2)Cr(CO)3 adsorbed on silica which had been pretreated in vacuum at temperatures in the range 250–800 °C or in H2O or D2O vapour at 700 °C. Surface isolated silanol groups formed hydrogen bonds with arene rings in Cr complexes which also interacted with the…
Antiferromagnetic Ni-Mn and hard-magnetic CoPt-Cr stabilization schemes for magnetoresistive (MR) sensors are evaluated in this paper. Magnetic properties of Ni-Fe(bottom)/Ni-Mn(top), Ni-Mn/Ni-Fe, Co-Pt-Cr, Ni-Fe/Co-Pt-Cr and Co-Pt-Cr/Ni-Fe films used in various types of MR sensors are characterized, and the read perf…
Summary This paper describes an investigation of the effect of tungsten on the HAZ properties of duplex stainless steel in a programme to develop highly pitting corrosion resistant duplex stainless steel. The steels tested were modified SUS329J4L duplex stainless steel containing added tungsten. The welded joints prod…
Abstract Polymer‐modified electrodes have been prepared by electrochemical oxidation of 2‐aminopyridine and 4‐aminopyridine in acetonitrile and their chemical properties have been characterized. The polymer films thus prepared were insulators but can be doped with Ag + or Fe(CN) to produce semiconducting films. The do…
Many types of proprietary processing aids are used by the manufacturers of polymer medical devices, which are difficult to completely eliminate from the end product. In such cases, it is important to investigate how such processing aids affect the properties of the materials. One such material is Pellethane and a most…
Novel poly(quinone diimines) from anthraquinones symmetrically disubstituted with solubilizing ethyleneoxy or long chain alkoxy groups have been synthesized and characterized. The disubstituted anthraquinones 1,5-bis(2-methoxyethoxy)anthraquinone (EO 1 AQ), 1,5-bis(2-(2-methoxyethoxy)ethoxy)anthraquinone (EO 2 AQ), 1,…
We report here the dramatic increase in fluorescence intensity of 7-diethylamino-4-methylcoumarin (coumarin 1) laser dye in the restricted geometry of a pillared clay nanocomposite. The fluorescence intensity of the alumina-pillared fluorphlogopite– coumarin complex is about 6 times greater than that of the fluorphlog…
This paper analyses the stress state in a circular ring under two opposite forces on its outer boundary. The solution is obtained by using the complex variable method and the principle of superposition. Stress concentration factors are calculated for the ratio of inner and outer radii in the range 0–0.95 and are prese…
The polymorphic behavior of poly(vinylcyclohexane) is discussed on the basis of conformational energy calculations on an isolated chain. The presence of two different modifications is in accordance with the energy minima present in the conformational energy maps. The packing of the chains in form I is analyzed on the…