Materials Literature
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Three new series of cyanoaryl 4-alkylthioxybenzoates have been synthesized and characterized. The 4-cyanophenyl series displays only transient mesomorphic properties while the 6-cyano-2-naphthyl and 4-cyanobiphenyl series exhibit the classical nematic and smectic A phases; a reentrant nematic phase is also found in th…
Abstract Good yields of arecolone and isoarecolone were obtained by treating the N,O ‐dimethylamides of arecaidine and isoarecaidine, respectively, with methylmagnesium chloride. Other substituted arecolones were synthesized by this same strategy.
SiC polycrystalline layers were deposited on a graphite substrate from a gas mixture of CH3SiCl3+H2(+Ar) at temperatures in the range of 800–1200 °C. The effects of the source gas flow rate (CH3SiCl3+H2), total pressure, linear velocity and Ar flux addition on the phase of the deposits were examined in some detail. Th…
The underlying physical principles of electromigration, which is one of the principal wearout mechanisms of the metal conducting tracks in LSI and VLSI circuits, are introduced. Track lifetime is believed to be influenced by the track dimensions, composition and passivation layer. These effects are considered. Differe…
Abstract Presently, a suitable theory to predict the T g vs. composition relationship for a given polymer‐plasticizer blend, based on detailed molecular structure and molecular energitics considerations, is not available. In particular, the plasticizer efficiency parameter, k , which is uniquely defined at low‐to‐mode…
Abstract Poly(l,4‐cyclohexylene dimethylene terephthalate) (PCT) exhibits superior heat deflection temperature when compared to conventional polyesters such as poly(butylene terephthalate) or poly(ethylene terephthalate). It is subject to degradation, however, at the processing temperatures normally employed to extrud…
Abstract The fundamental skeleton of the tropones possessing a unique heptagonal structure is predicted to be aromatic with positive resonance energies and conforming to the topological charge stabilization rule (TCS rule). Similarly, naturally occurring tropolones also nicely fit the theory that conformity to the TCS…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCharacterization of ammonia-ligated low-spin iron(III) porphyrin complexesYunghee Oh Kim and Harold M. GoffCite this: Inorg. Chem. 1990, 29, 19, 3907–3908Publication Date (Print):September 1, 1990Publication History Published online1 May 2002Published inissue 1 September 199…
The dielectric polarization has been used to study dipolar association of 4-n-pentyl-4′-cyanobiphenyl in benzene solution. The results have been interpreted with the assumption of a monomer–dimer equilibrium. To explain the relatively high effective dipole moment of the dimers, a new structure has been proposed for th…
Abstract The time for brittle failure by slow crack growth for 22 polyethylene copolymers was measured in Igepal and air. The notched tensile tests were conducted in Igepal and air at 50°C and 4.2 MPa and in air at 80°C and 2.4 MPa. For failure times less than 10 3 min, the difference between the Igepal and air enviro…
Single-crystal MgO and SrTiO 3 substrates have been raised to temperatures suitable for deposition and in situ annealing of high-T c superconducting thin films by the absorption of 10.6 mu m laser radiation. Steady-state temperature control in vacuum and low-pressure oxygen was achieved by varying the mark-space ratio…
Abstract : Sections of CDA 706 piping and Monel 400 tubing were severely pitted after exposure to marine and estuarine waters, respectively. Surfaces of both alloys were uniformly covered with thick surface deposits, ranging in color form blue-green to reddish brown to black. Pits developed under surface deposits cont…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochromic molybdenum trioxide thin film preparation and characterizationDaniel Belanger and Guylaine LaperriereCite this: Chem. Mater. 1990, 2, 5, 484–486Publication Date (Print):September 1, 1990Publication History Published online1 May 2002Published inissue 1 Septembe…
The photoluminescence decay of the CaS:Mn 2+ phosphor activated with a fairly large amount of Mn 2+ (1-2mol%) consists of slow (8.5 ms at 80 K) and fast (550 µs at 80 K) exponential decay components due to the single and paired Mn 2+ centers, respectively. From the measurements of time-resolved emission spectra, the e…
Abstract The hemithioindigo derivatives have been found to show satisfactory photoresponses even after more than 104 cycles of alternate irradiation with the lights which can induce a Z–E isomerization.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, electrochemistry, and kinetic investigations of low-spin ferrous bis(difluoroboryl)bis(dioximate) complexesDavid W. Thompson and Dennis V. StynesCite this: Inorg. Chem. 1990, 29, 19, 3815–3822Publication Date (Print):September 1, 1990Publication History Published…
Abstract Bis(trimethylsilyl)bisphenol‐A was condensed with 4,4′‐dichlorodiphenyl sulfone under various reaction conditions. Satisfactory yields and molecular weights of the resulting poly(ethersulfone)s were only obtained when the condensation was conducted in amide solvents (e. g., N ‐methyl‐2‐pyrrolidone) in the pre…
The fusion reactor represents the most difficult challenge of any energy system from the viewpoint of developing materials which will allow fusion to be realized as an economic, safe and environmentally acceptable energy source. Substantial progress has been made over the past decade towards an understanding of the ef…
The electro-optic performance characteristics of PDLC films using two different polymers, namely, poly (methyl methacrylate) (PMMA) and poly (vinyl chloride:vinyl acetate 17%) (PVC:VAC-17) and liquid crystal mixture E-8 (BDH, England) have been studied. It is found that the PMMA-based PDLC films have more superior mec…
Sixteen azobenzene derivatives were used as guests in an ester-type host liquid crystal (LC), 4-hexy- loxyphenyl-4′-ethyl-cyclohexanecarboxylate (ECH 206), and were examined on their ability to induce the photochemical isothermal phase transition of the guest/host mixtures. Attention was focused on the effect of the m…