Materials Literature
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The temperature dependence of the upper critical magnetic field ${H}_{c2}(T)$ in the quasi-one-dimensional molecular superconductor (TMTSF${)}_{2}$P${\mathrm{F}}_{6}$ was determined via resistivity, for the intrachain (a), interchain (b), and interplane $({\mathbf{c}}^{*})$ directions. For H along a and b, ${H}_{c2}(T…
The possibility of thermodynamic correlation of partial and saturation swelling of styrene-acrylonitrile (SAN) copolymer particles by styrene (St) and acrylonitrile (AN) monomers is investigated. The unknown Flory-Huggins interaction parameters involved in the thermodynamic swelling equations are estimated by fitting…
Cooperative upconversion processes and Yb-Er energy transfer efficiencies in high Er concentration phosphate glasses were studied. The cooperative upconversion coefficients were deduced from the pump intensity dependence of luminescence decay curves. Cooperative upconversion coefficients of <SUP>4</SUP>I<SUB>13/2</SUB…
The organic template within molecular sieves may readily be studied by FT–Raman spectroscopy with virtually no interference from bands due to framework vibrations. FT‐Raman spectra show that morpholine and cyclohexylamine are in the protonated form within AlPO 4 ‐based materials with the chabazite structure, while spl…
Surface modification of poly(p-phenylene terephthalamide) (PPTA) film by a remote oxygen plasma treatment has been investigated from a viewpoint of comparison with a direct oxygen plasma treatment. We call the modification procedure in a space far away from the oxygen plasma zone “the remote oxygen plasma treatment,”…
Rosetten , die durch Wasserstoffbrückenbindungen zusammengehalten werden (rechts), können aus komplexchemisch hergestellten Metallodendrimeren synthetisiert werden. Somit werden zwei orthogonale, nichtkovalente Wechselwirkungen (Metall‐Ligand‐ und Wasserstoffbrückenbindungen) zum Aufbau dieser nanometergroßen Dendrime…
Ohne zu haften rollen Tropfen von Rübsamenöl (siehe Bild) auf einer Oberfläche herum, die in zwei Schritten hergestellt werden konnte: Ein Aluminiumblech wird zuerst durch anodische Oxidation aufgerauht und dann mit fluorierten Monoalkylphosphaten behandelt. Der Kontaktwinkel einiger polarer Öle auf derartigen Oberflä…
A two-step process for lactic acid polymerization is studied: in the first step the lactic acid is condensation-polymerized to a low-molecular-weight hydroxyl-terminated prepolymer; and then the molecular weight is raised by joining prepolymer chains together using diisocyanate as the chain extender. The resulting pol…
The thermal recovery of the stored stress in crosslinked polyethylene has been commercially exploited in the preparation of heat shrinkable materials. The study on thermally recoverable crosslinked polyethylene compositions is reported in this paper. Thermally recoverable compositions were prepared by cross-linking of…
The porphyrin–prophyrin distance and the spatial requirements of the porphyrin substituents are parameters that influence the rotatability of the ligands in metal bis(porphyrinate)s (shown on the right): the chiral cerium complexes were much easier to racemize than the zirconium complexes. The porphyrin ligands in the…
The heavy-metal chelating properties of a soy protein based hydrogel, prepared by crosslinking an ethylenediaminetetraacetic acid dianhydride (EDTAD) modified soy protein isolate (SPI), have been studied. The equilibrium binding capacities of the divalent calcium, zinc, mercury, and lead ions by the gel were 0.70, 0.6…
The physical and thermal properties of hand-cast polyurethane and polyurethane/polyurea elastomers prepared from prepolymers of 20 and 97% trans,trans-4,4′-diisocyanatodicyclohexyl methane (t,t-rMDI) and C3- and C4-polyethers chain extended with either 1,4-butanediol (XB) or a commercial mixture of diethyl toluenediam…
Excellent yields of the carbaporphyrin 1 are obtained by application of the “3 + 1” methodology for the reaction of 1,3-indenedicarboxaldehyde with a tripyrrane in the presence of 5% CF3CO2H in CH2Cl2. The related formylcarbaporphyrin 2 was prepared similarly. In contrast to earlier claims, no unusual tautomers or con…
Through “electronic separation” of the seven-membered ring the formally cross-conjugated, azulene-containing macrocycle (limiting structure A) becomes a porphyrinlike species with a weak, diamagnetic ring current (limiting structure B). This aromatic character is further accentuated upon twofold protonation.
Abstract It is a great challenge to synthesize compounds containing planar‐tetracoordinate carbon that are stable enough to be isolated, investigated, and handled under ambient conditions. There have therefore been many attempts to construct hydrocarbon frameworks that can incorporate and stabilize tetravalent carbon…
Isothermal melt crystallization of poly(L-lactide) (PLLA) has been studied in the temperature range of 90 to 135°C. A maximum in crystallization kinetic was observed around 105°C. A transition from regime II to regime III is present around 115°C. The crystal morphology is a function of the degree of undercooling. At c…
Soft chemical methods were used for preparing the new class of composite materials presented here. One example is [{Cu(4,4′-bpy)}4Mo8O26] (4,4′-bpy = 4,4′-bipyridine), whose unique structure (shown on the right) consists of [Mo8O26]4− clusters embedded in a web of {Cu(4,4′-bpy)} one-dimensional chains.
Abstract Some chemical and mechanical properties of intermediate products obtained in the production of PE heat shrinkable tubes were studied, seeking correlations between the composition and the properties. Different PE granulates were mixed with antioxidant (amine or phenol derivative), flame retardant agent and, fo…
Three modified bismaleimide resin systems (designated as systems I, II, and III) for high-performance radomes are introduced. Their glass transition temperatures are 274°, 268°, and 265°C, respectively; and their dielectric loss tangents at 10 GHz are 0.0117, 0.0108, and 0.0118, respectively. System I and system II ar…
The excited states of many organic molecules are sufficiently long lived so that excitation gives rise to a change in the absorption spectrum that persists for seconds or even longer. The author is unaware of any perfect crystal for which this is true. Vacancies are essential to the appearance of photchromism in alkal…