Materials Literature
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The electrochemical deposition of polypyrrole (PPy) potentiodynamically and potentiostatically over monolayers of 1-(2-thioethyl)pyrrole (1-TEP) is described. The relationship between monolayer oxidation and PPy growth depended strongly on the electrolyte. In propylene carbonate/LiClO 4, the PPy polymerization potenti…
S2 p and O1 s photoelectron spectra were obtained for the 95(0.6Li 2 S0.4SiS 2 )5Li 4 SiO 4 oxysulfide glass prepared by twin‐roller quenching. A four‐peak deconvolution technique was used to separate the S2 p peak of the glass into the components of bridging and nonbridging sulfur atoms. As a result of the deconvolut…
Electronic and structural properties of polypyrroles oxidized by different concentrations of chlorine atoms or molecules are studied with the use of a density functional method implemented with plane waves and pseudo-potentials for the core electrons. The calculated properties are compared with those obtained for the…
Shape memory alloy (SMA) wires can be embedded in a host material to alter the stiffness or modal response and provide vibration control. The interaction between the embedded SMA and the host material is critical to applications requiring transfer of loads or strain from the wire to the host. Although there has been a…
The motion of charge carriers in many solid ionic conductors is determined both by long-range Coulomb interactions and by structural disorder in the host matrix. While the dynamical behaviour at low frequencies is governed by long-range, thermally activated hopping processes, localized motions of the charge carriers w…
During the synthesis of ZnS powders by wet chemical precipitation, the formation of nanoporous spheres is observed. The powders have been investigated using thermogravimetric analysis, X-ray diffraction and optical spectroscopies. Nanopore formation can be explained by several stages of growth. The formation of nanopa…
A ridge and fringe field multi-domain homeotropic (RFFMH) liquid crystal display was demonstrated. The operating principle of this new display mode is the combination effect of a fringe field and ridge structure to control the tilt direction of the liquid crystal molecules when a voltage is applied. No rubbing treatme…
The nucleation and growth of wollastonite crystals have been investigated in stoichiometric CaO⋅SiO2 glass. In the temperature range of 1043 to 1073 K, the nucleation rate was evaluated from crystallite densities, determined by optical microscopy on samples subjected to double-stage heat treatment. Turnbull’s method w…
A negative temperature coefficient of electrical resistivity (TCR) has been observed in Ti 50- X Ni 50+ X (at.%; X =1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5) in the temperature range between 20 and 350 K. The resistivity vs temperature curve has no hysteresis and the relative resistivity at 20 K (ρ 20 K /ρ 350 K ) decreases…
Thermally stimulated depolarization currents (TSDC) and differential scanning calorimetry (DSC) have been used to study the effect of physical ageing in polyetherimide (PEI: ULTEM 1000™). Ageing temperatures (Ta) between 48 and 8°C below the glass transition temperature (Tg) measured by DSC at 10°Cmin-1 heating rate (…
The synthesis and mesomorphic properties of several homologues of (S)-(+)-1-methylheptyl 4-[4(trans-4-n-alkoxycinnamoyloxy)benzoyloxy]benzoates (series I) and (S)-(+)-1-methylheptyl 4-[4-(trans-4-n-alkoxy-alpha-methylcinnamoyloxy)benzoyloxy]benzoates (series II) are described. The influence of the alpha -methyl group…
This paper describes studies of some photophysical properties of non-covalent planar aggregates of hematoporphyrin and protoporphyrin. This porphyrin species has been recently discovered and can be generated in lipid bilayers such as liposomes and inner mitochondrial membranes. The relative weight of this species in d…
In this study, we sputter deposited titania films of thickness ranging from 256 to 705 nm on unheated substrates and studied changes in phase constituency as a function of film thickness. X-ray diffraction, and infrared spectroscopy were used for post-deposition analysis. The results show that the thinnest films consi…
Abstract Semi-crystalline polyolefins, e.g. , polypropylene in its isotactic and syndiotactic forms, become brittle at low temperature due to their inherent crystallinity and relatively high T g . It has been discovered that certain “non-polar” aliphatic esters, in particular monomeric tallates and sebacates can effec…
This work compares the fire degradation of ethylene-vinyl acetate 8% copolymer (EVA8) with two flame-retarded formulations, using the cone calorimeter. The first one, EVA8/ammonium polyphosphate (APP) leads to the protection of the material, in the conditions of a fire, by means of blowing up and weak carbonization. T…
Nucleation and crystallization studies were conducted on a YSiAlON glass that contained 17 equiv.% nitrogen (7.5 at.%) by using a two‐stage nucleation‐and‐growth treatment. Classical and differential thermal analysis (DTA) techniques were both used to study the crystallization process, to ensure that the optimum heat‐…
Densification of alumina coated with a MgO‐Al 2 O 3 ‐SiO 2 (MAS) glass was investigated from 1400° to 1460°C. Spinel was observed to form at the liquid‐alumina interface, whereas mullite crystallized uniformly in the liquid. Spinel and mullite crystallization kinetics were accelerated by smaller alumina particle size.…
We have studied the temperature variation of conductivity and 1H NMR linewidth of (PEG)xNH4ClO4 (x = 20, 30, 46, 100, 200, & 1000) polymer electrolyte systems. The temperature dependence of the conductivity shows two distinct behaviors, the low temperature VTF dependence crossing over to Arrhenius dependence at higher…
Relaxations in poly(etherimide) PEI Ultem 1000 have been analysed by differential scanning calorimetry (DSC), dynamic mechanical spectroscopy (DMS), dielectric relaxation spectroscopy (DRS) and thermally stimulated depolarization current (TSDC) measurements. DMTA and DRS results show three distinct relaxations γ, β an…
In the present study, conductive polyaniline-p-toluene sulfonic acid (PANI-pTSA) blends with thermoplastic polymers were prepared by melt processing. The blends′ characterization focused on their morphology in light of the components′ interaction and the resulting electrical conductivity. The PANI-pTSA blends were com…