Materials Literature
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Abstract Thermal dehydrochlorination of trans ‐6(4)‐chloro‐4(5)‐tetradecenes, models for PVC degradation, was studied by NMR spectroscopy both alone and in the presence of alkyl and zinc phosphites. The implications of these results on PVC degradation and stabilization are discussed.
Two chemical treatments were applied to hemp, sisal, jute and kapok natural fibres to create better fibre to resin bonding in natural composite materials. The natural fibres have been treated with varying concentrations of caustic soda with the objective of removing surface impurities and developing fine structure mod…
Abstract Sandstones and mudstones of the Skagerrak Formation from the Danish Sub-basin have been studied to assess the origin of the clay minerals, their diagenesis and their transformation/ conversion temperatures (compared to modelled maximum burial temperatures). Detrital smectite and vermiculite occur only at shal…
Thermal conversion of poly(anthranilic acid) (PANA) to polyaniline (PAn) has been studied by means of thermogravimetric/mass (TG/MS) and Fourier transform infrared (FTIR) spectroscopy. The electrical conductivity of the chemically prepared PANA was 3.5 × 10−2 S/cm, which is caused by the self-doping of the polaronic n…
Perhaps one of the most surprising results in the past 10 years was the prediction of Brand et al. [1] that fluid biaxial smectics made from comopunds without asymmetric carbons could, by symmetry, have a spontaneous polarization, P, in the layer plane. They called this construct, which can be either ferroelectric or…
Ongoing studies of the CsHSO(4)-CsH(2)PO(4) system, aimed at developing novel proton conducting solids, resulted in the new compound Cs(2)(HSO(4))(H(2)PO(4)) (dicesium hydrogensulfate dihydrogenphosphate). Single-crystal X-ray diffraction (performed at room temperature) revealed Cs(2)(HSO(4))(H(2)PO(4)) to crystallize…
Abstract The mechanical behavior of polycarbonate (PC) coextruded as microlayers with a brittle polymer, either poly(styrene‐ co ‐acrylonitrile) (SAN) or poly(methyl methacrylate) (PMMA), was examined. Adhesion between layers was measured with the T‐peel method. The much higher interfacial toughness of PC/PMMA microla…
As propriedades tênseis de compósitos de matriz poliéster, reforçados por fibras curtas de sisal foram determinadas em função do comprimento, teor e orientação das fibras. Os resultados mostram que, para os compósitos investigados, a resistência à tração aumentou com o comprimento das fibras (5 – 45 mm), atingiu um pl…
Crystallization behavior of potassium niobium silicate (KNS) glasses having compositions expressed by the general formula x K 2 O· x Nb 2 O 5 ·(1 ‐ 2 x )SiO 2 , with x = 0.167, 0.182, 0.200, 0.220, and 0.250, has been studied by DTA, X‐ray diffraction, second harmonic optical generation (SHG), and electron microscopy.…
Thin amorphous and polycrystalline tungsten oxide films were prepared by chemical vapour deposition at atmospheric pressure from a metalorganic precursor — tungsten hexacarbonyl. The dependence of the structural and optical properties of tungsten oxide films on the technological conditions has been investigated by XRD…
The nonlinear dynamics of a spherical bubble cloud with nuclei size distribution are studied numerically. The spectrum of nuclei is assumed uniform initially. The simulations employ a nonlinear continuum bubbly mixture model with consideration of the presence of bubbles of different sizes. This model is then coupled w…
The interaction and adhesion between the fiber and matrix has a significant effect in determining the mechanical and physical behavior of fiber composites. The effect of the interface and interphase depends on several factors such as chemical composition (functional groups), molecular structure characteristics (branch…
This paper deals with two different types of composite insulating materials for HV outdoor insulation technology. For outdoor applications fiberglass reinforced polymer (FRP) are used mainly as transmission line insulators (composite long rods),and as power apparatus housings (composite hollow core insulators). During…
Neutron diffractometry and X‐ray diffractometry were used to characterize the cation disorder and vacancy distribution in nonstoichiometric spinel, MgO· x Al 2 O 3 , where x greaterthan equal to 1.0. Both synthetic and natural samples were examined. Least‐squares refinements of integrated intensities for single crysta…
An iron(III) complex [Fe(salten)(Mepepy)]BPh4 containing only one photoisomerizable ligand (Mepepy) has been synthesized, it exhibits a thermally-induced spin crossover in the solid state and in solution {H2salten = 4-azaheptamethylene-1,7-bis(salicylideneiminate); Mepepy = 1-(pyridin-4-yl)-2-(N-methylpyrrol-2-yl)ethe…
The synthesis and general chemical physical characterization of the following new classes of complexes derived from tetrakis(thiadiazole)porphyrazine (TTDPzH(2)), i.e., [(TTDPz)M(DMSO)(2)] (M = Mn(II), Fe(II)), [(TTDPz)M](H(2)O)(2), and [(TTDPz)M] (M = Mn(II), Fe(II), Co(II), Ni(II), Zn(II)) are reported. The IR spect…
The bioplastic PHB/HV (copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate) underwent a faster degradation at 30°C than at 52°C in soil under aerobic conditions, while there was no remarkable difference between 30°C and 52°C in the degradation rate of PCL [poly(ε-caprolactone)], PBSA (polybutylene succinate and agipa…
Carboxylic acids are found to adsorb weakly to the native oxide surface of aluminum. Under heat exchange conditions, synergistic carboxylate combinations provide superior high-temperature aluminum corrosion protection and show excellent heat-transfer characteristics. The surface films formed under these dynamic heat-t…
Four formulations of magnesia‐graphite‐aluminum metal (antioxidant) bricks were prepared from the same raw materials, using the standard commercial practices. Chemical analysis and determination of room‐temperature modulus of rupture and Young's modulus, as well as a complete microstructural characterization of the as…
Abstract The IR spectra of -saturated smectites were examined in terms of their charge characteristics. The υ 4 band near 1440 cm -1 , observed in the DRIFTS spectra (obtained without use of a KBr matrix), was assigned to the vibrations of ions compensating the negative charge of the clays. When KBr was used as a dilu…