Materials Literature
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The catalytic wet-air oxidation and catalytic ozonation of a formic acid solution have been studied at room temperature using more than 20 kinds of catalysts including Pt/C, Pt/Al2O3, Pd/Al2O3, etc. The most effective catalyst was Pt/Al2O3. The apparent activation energies for the catalytic wet-air oxidation and ozona…
The fracturing of four different polyolefin materials (a polypropylene homopolymer, a propylene–ethylene copolymer, a polyethylene homopolymer, and an ethylene–hexene copolymer) was studied with the objective of developing a better understanding of the relationships between the morphology of semicrystalline polymers,…
In a two-component system combining an oligophenylenevinylene (OPV) group with a protonable phenanthroline unit, the direction of intercomponent photoinduced energy transfer can be tuned by proton input, thus allowing on/off switching of the luminescence of the OPV moiety.
Solid wastes represent a potential source for raw materials in the world. In Brazil, municipal solid waste (MSW; 2–%) is expected to grow at a rate per year higher than the worldwide rate (1%). On the other hand, the consumption of polymer blends increases at a rate more than twice that of all plastics. Therefore, the…
The electronic and vibrational hyperpolarizabilities of polyenes NH2–(HC=CH)n–NO2 and polyynes NH2–(C≡C)n–NO2 have been investigated. As the chain length increases, the first hyperpolarizabilities increase drastically for polyenes, while they increase moderately for polyynes. Furthermore, in polyenes the vibrational f…
The cyclooctadiene ligand within the square planar Pt(II) complex [PtCl2(C8H12)] undergoes nucleophilic attack from a siloxo group of the thallated polyhedral silsesquioxane [(c-C5H9)7Si7O9 (OSiMe3)(OTl)2], to yield [(c-C5H9)14Si14O 18(OSiMe3)2O4(η4 -C8H12)PtTl2]; given the analogy between the silsesquioxane moiety an…
Newly prepared octakis{4-[N-(4′-heptyloxyphenyl)iminomethyl]phenoxy }cyclotetraphosphazene, consisting of a cyclotetraphosphazene ring backbone and Schiff base side-chain groups has been found to generate an enantiotropic smectic A phase; this is a first example of a mesomorphic cyclotetraphosphazene.
The crystal structure of the new mixed oxalate Y(H2O)Cs(C2O4)2 has been solved from powder X-ray diffraction data. The compound is isostructural with the related yttrium ammonium oxalate. It crystallises with monoclinic symmetry, a = 8.979(2), b = 6.2299(8), c = 8.103(1) Å, β = 90.05(2)° and V = 453.3 Å3, in space gro…
Dynamics of a spherical bubble cloud with nuclei size distribution is investigated numerically when the surrounding pressure is decreased from 50kPa to 10kPa and then increased to 50kPa stepwisely. A set of governing equations for the motion of bubble cloud are formulated combining the averaged equation and the equati…
We have studied a system of discotic particles with a central transverse dipole using Monte Carlo (MC) computer simulations at constant pressure. We have investigated several temperatures corresponding to nematic and columnar liquid crystal phases and determined the molecular and dipolar organizations. Low temperature…
A family of Mannich bases were prepared from the reaction of 2,2-bis-(4-hydroxyphenyl)propane (bisphenol A or BPA), formaldehyde, and poly(oxyalkylene)diamines at 1 : 1 : 1 or 1 : 2 : 2 molar ratio. By varying the molar ratio of bisphenol A to amine and the chemical structures of poly(oxyalkylene)diamines, a series of…
Mesoporous dimethylsiloxane-incorporated silica materials are synthesized which exhibit high surface areas, regular mesopores, thick walls, high hydrophobicity and high mechanical strength.
Composites produced during the in situ chemical polymerization of aniline on top of a poly(ethylene terephthalate) (PET) film, in different conditions, were studied by open-circuit potential (Voc), ultraviolet-visible, and infrared spectroscopy, electrical conductivity measurements, scanning electron microscopy, and a…
We report here on poly(amino acid)-based bioadhesives with potential to bond to soft tissues. The systems investigated included homopolymer poly(amino acids), mixtures of poly(amino acids) and amino acids, and blends of different poly(amino acids). Adhesive performance was tested in tension on glass surfaces, chondroi…
The microhardness, H, of carbon black–polycarbonate and carbon black–low-density polyethylene composites was investigated. Two types of microadditives with different average particle sizes were employed. It has been shown that the morphology of the polymeric matrix conspicuously influences the hardness dependence of t…
Small-angle neutron scattering (SANS) was used to examine the melt phase behavior of a heavily branched comb PEE polymer blended separately with two linear PEE copolymers. In this case, PEE refers to poly(ethylene-r-ethylethylene) with 10% ethylene units; therefore, the molecular architecture was the only difference b…
The thermoelectric properties of sintered bodies of NaCo2O4, which is so far the most promising p-type candidate for oxide thermoelectric material, are investigated in terms of their sintering conditions. Double-step sintering, for which single-phase NaCo2O4 obtained by calcination and sintering with addition of 10% e…
Surface-enhanced Raman scattering (SERS) is a process with origins, electromagnetic and chemical. The electromagnetic enhancement consists of the excitation of surface plasmons in the metallic support of the thin film. With only the electromagnetic enhancement mechanism, the surface spectra should not differ from volu…
Glycidyl methacrylate (GMA) was grafted on ethylene–propylene copolymer during melt processing with peroxide initiation in the presence and absence of a more reactive comonomer (coagent), trimethylolpropane triacrylate (Tris). The characteristics of the grafting systems in terms of the grafting reaction yield and the…
The synthesis and structural characterisation of a novel metal polyhedron is reported, involving chromium(III) and isobutyrate; comparison of this product with those obtained using different carboxylates suggests that the leaving group—which can be carboxylate, water or both—strongly influences the structure found.