Materials Literature
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Synthetic polymers are the most widely used materials for packaging because of their ease of processing, low cost, and low density. However, many of these materials are not easily recyclable and are difficult to degrade completely in nature, creating environmental problems. Thus, there is a tendency to substitute such…
Abstract Experiments on thermal decomposition of calcium carbonate were carried out in a thermogravimetric analyser under non‐isothermal conditions of different heating rates (10 to 100°C/ min). A new technique for determining the kinetic parameters from non‐ isothermal thermogravimetric data was described. The activa…
This article concerns the functionalization of polypropylene (PP) with oxazoline functionality by melt free radical grafting along with a low degree of degradation of PP in a batch mixer. A low volatile oxazoline, ricinoloxazoline maleinate (OXA), was used as the monomer. The grafting yield of OXA ranged from about 0.…
A simple and accurate method of measuring the surface torsional anchoring strength of nematic liquid crystals is proposed. This method is based on the simultaneous determination of the actual twist angle and the cell gap (optical retardation) of a twisted nematic cell in which the easy axes of the upper and lower subs…
BACKGROUND: Two cases of allergic (IgE-mediated) reaction to bovine collagen are described. Both patients developed conjunctival oedema in response to the topical application of highly purified bovine collagen to the eye during opthalmic surgery (corneal shields and catgut suture material). One patient developed perio…
Atomic force microscopy, a powerful, high‐resolution imaging technique for determining the structure of surfaces in gaseous and liquid environments, was used to examine the reactivity of an electropolished surface of a naturally aged aluminum‐copper‐magnesium alloy (2024‐T3) in aqueous hydrochloric acid (0.01, 0.1, an…
Thermodynamic properties of the Cu-Ti system were optimised using experimental thermochemical and phase diagram data from the literature, leading to a consistent set of Gibbs energy parameters for the thermodynamic description of its equilibrium phases. Non-stoichiometries of the compounds Cu4Ti and CuTi were taken in…
Abstract A new morphology of ternary ABC triblock copolymers is presented which results from the asymmetric interaction between a centre block (poly(ethylene‐ co ‐butene)) to different end blocks (polystyrene and poly(methyl methacrylate)). This morphology with the appearance of a “knitting pattern” can be described a…
Abstract Shape memory polymers were prepared by copolymerizing stearyl acrylate and methyl acrylate. The principle of this shape memory effect is based on reversible order‐disorder transition of crystalline aggregates of stearyl moieties. A specific feature of this type of shape memory copolymer is that the transition…
Abstract The synthesis of the first example of an aromatic pyridine‐containing porphyrinoid 10 has been accomplished in excellent yields by the acid‐catalyzed “3 + 1” condensation of 3‐hydroxy‐pyridinedicarboxaldehyde ( 8 ) with tri‐pyrrane 9 . The key intermediate 8 was obtained by the selenium dioxide oxidation of t…
Gallium is a metal that literally melts in your hand. It has low toxicity, near-zero vapor pressure, and a viscosity similar to water. Despite possessing a surface tension larger than any other liquid (near room temperature), gallium can form nonspherical ...Read More
The control of chirality by optical molecular switches offers intriguing prospects in the design of new materials. For example, photochemically induced stilbene‐type cis‐trans isomerization of 1 (see Figure) results simultaneously in reversal of the helicity. The molecular design of switching units, the possibility of…
The cell parameters of deuterated gypsum have been extracted from Rietveld analysis of powder neutron diffraction data within the temperature range 4.2-320 K. The thermal expansion of gypsum is highly anisotropic along the b axis principally because of the effect of the D2.. .01 hydrogen bond. The high-temperature lim…
Prenyltransferases catalyze the consecutive condensation of isopentenyl diphosphate with allylic diphosphates to produce prenyl diphosphates whose chain lengths are absolutely determined by each enzyme. To investigate the mechanism of the consecutive reaction and the determination of the ultimate chain length, a rando…
A quantitative model for liquid phase sintering is developed based on the following ideas. During heating a liquid phase forms, which is easily mobile, wets the solid particles completely, dissolves solid atoms and provides an easy diffusion path for them. The solid density increases by particle rearrangement and by t…
Abstract Progress on the area of passivation of metallic materials by polyaniline is being presented. The redoxcatalytic reaction leading to the formation of a passivating oxide layer has been evaluated, and a reaction scheme is shown. Results of corrosion tests are described as well.
Structural, transport, and magnetic properties of ${\mathrm{Nd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ca}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$ (0\ensuremath{\le}x\ensuremath{\le}1) have been studied to probe the consequence of strong lattice distortion and reduced double exchange. Charge ordering has been obse…
No abstract available.
Optoelectronic components require materials with large second‐order nonlinearities. Recently, various types of non‐classical chromophores have been developed, in the hope that they have improved physical properties for materials formation. The main research directions and latest developments reviewed here include mult…
Abstract The relationship between catalyst structure and enantioselectivity in the asymmetric epoxidation of unfunctionalized olefins by a series of chiral Mn(sa1en) complexes (1 – 10) was examined. The X‐ray structures of 5‐coordinate complexes 5, 8, of 6‐coordinate 9 ([6,6′= ‐ t Bu; 4,4 = ‐ t Bu] + ClO 4 − ), and 10…