Materials Literature
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Six different phosphazene polymers have been synthesized with varying ratios of 2-(2-methoxyethoxy)ethanol and diacetone D-glucofuranose to determine how these pendant groups affect the physical, chemical, and thermal characteristics of these terpolymers. Diacetone D-glucofuranose serves as the hydrophobic substituent…
The mechanisms of reactions causing irreversible inhibition of the activity of enzymes when irradiated in the presence of the recently developed alpha-methyl-6-nitroveratryl-based photolinker [Holmes CP. J. Org. Chem. 1997; 62: 2370-2380] have been investigated. Several experiments based on the interaction of the phot…
The concept of frustrated phase separation is applied to investigate its consequences for the electronic structure of the high T c cuprates. The resulting incommensurate charge density wave (CDW) scattering is most effective in creating local gaps in k-space when the scattering vector connects states with equal energy…
For pt.1 see ibid., previous issue. Soap bubbles are fragile, beautiful phenomena. They're fun to make and play with, and their geometry is as clean and elegant as anything in nature, which makes them particularly suited to computer graphics. In pt.1 I discussed the nature of soap films. These thin sheets of soapy wat…
Single-crystal aluminas are being considered for use in the manufacture of prosthetic heart valves. To characterize such materials for biomedical application, subcritical crack growth by stress corrosion (static fatigue) and by cyclic fatigue has been examined in sapphire along (1100) planes in 24 degrees C humid air…
Ultrahigh molecular weight polyethylene (UHMWPE) samples were implanted with 46 and 80 keV nitrogen ions up to a fluence of 1017 ions cm−2. The modified surface layers were studied by XPS, Fourier transform infrared spectroscopy (FTIR), Rutherford backscattering spectrometry, elastic recoil detection analysis and dyna…
ZnS films were synthesised using a novel electrostatic assisted aerosol jet deposition (EAAJD) technique at temperatures above 450 °C from an aqueous solution of zinc chloride and thiourea. The films showed a mixture of hexagonal and cubic structures and strong preferred orientations, with the c-axis normal to film su…
SiO2–GeO2 films have been synthesized by the sol–gel method starting from an ethanolic solution of Si(OC2H5)4 and Ge(OCH3)4. The coatings have been annealed in air at temperatures ranging between 300 °C and 900 °C. The compositional and microstructural evolution of the samples under thermal annealing has been investig…
The present study was conducted to compare the structure and properties of conventional and so-called “high-crystallinity” (hcr) polypropylene (PP) and to establish characteristic features of the latter that are responsible for its superior thermal and mechanical performance. Moreover, structure–properties relationshi…
The photochemical properties of some lanthanide chelates developed for immunohistochemistry have been studied in water and in solid Langmuir-Blodgett films. The fluorescence and triplet-state lifetimes of 4-(phenylethynyl)pyridine (PET), di[(phenylethynyl)pyridine] (D-PET), phenylterpyridine (PTP) and their tetra- or…
Three thermoplastic polyurethane elastomers (TPUs) were prepared using the prepolymer method. MDI (diphenylmethane-4,4′-diisocyanate) and the polyadipate of 1,4-butanediol (Mw = 2400) were reacted to produce a prepolymer containing unreacted isocyanate groups; chain extenders were different mixtures of 1,4-butanediol…
Low temperature polarized single-crystal absorption and luminescence spectra of Cr(V)-doped YVO4 and the powder luminescence spectrum of Cr(V)-doped YPO4 are reported and discussed. A rich fine structure and strong polarization effects are observed in the near-infrared. Due to a strong interaction of the Cr(V) ion wit…
A thermodynamic study of the Ti–O system at 1573 K has been conducted using a combination of thermogravimetric and emf techniques. The results indicate that the variation of oxygen potential with the nonstoichiometric parameter δ in stability domain of TiO2−δ with rutile structure can be represented by the relation, Δ…
Protonic conductivity measurements are reported for H3PW12O40x21H2O single crystals in the temperature range 77 to 303 K. At room temperature, the conductivity is 0.18 Sm-1 and falls to a minimum of 0.26×10-3 Sm-1 at 188 K. An anomalous behavior in conductivity observed in the temperature range 263 to 283 K is reporte…
The association strength of positively charged porphyrins with anionic species can be orders of magnitude higher than reported in the literature, depending on the chosen buffer; the buffer also determines the dominating interaction mechanism, leading to stronger stacking contributions at higher salt concentrations; ev…
On the addition of β-cyclodextrin, the proportion of the photoactive anti-parallel conformation of photochromic 2,2′-dimethyl-3,3′-(perfluorocyclopentene-1,2-diyl)bis(benzo[b]thiophen-6-yltrimethylammonium) iodide (1a) increased, and the cyclization quantum yield was found to increase. On the other hand, the proportio…
The high-speed melt spinning of sheath/core type bicomponent fibers was performed and the change of fiber structure with increasing take-up velocity was investigated. Two kinds of polyethylene, high density and linear low density (HDPE, LLDPE) with melt flow rates (MFR) of 11 and 50, [HDPE(11), LLDPE(50)], and poly(et…
In this work, the solvent effect on the miscibility between poly(vinyl chloride) (PVC) and poly(methyl methacrylate) (PMMA) in ternary polymer solutions was examined by the viscometric method. In these systems, we could understand that the used solvents, tetrahydrofuran (THF) or N,N-dimethylformamide (DMF), mainly aff…
Abstract Knowledge of the Young's moduli is necessary for piezoelectric ceramics in order to separate the total deformation into an elastic and a plastic contribution. The methods for the determination of the Young's moduli, well known from conventional ceramics, are much more complicated due to the special electrical…
Extending the useful life of materials through recycling has proven to be an efficient means of reducing natural resource use and limiting the production of waste. In the case of polymer-based materials, in general, and of packaging materials, in particular, material recovery is complicated by the presence of incompat…