Materials Literature
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The effects of various vulcanization systems and fillers in epoxidized natural rubber (ENR) at 50% epoxidation (ENR 50 compounds) were examined. ENR compounds cured with the semi-EV (efficient vulcanization) system showed the shortest cure and scorch times but the highest torque values. White rice husk ash (WRHA) fill…
Manganese(II)chloride, bromide, acetate and L-lactate were used as catalysts for the polymerization of L-lactide. All polymerizations were performed in bulk and despite a high reaction temperature (150°C), long reaction times (192 hours) were needed to achieve nearly complete conversions. Mn L-lactate was found to be…
The dielectric propereties of smectic liquid crystal mixtures containing chiral dopants derived from trifluoromethylated pyranose were studied. In every mixture, a large dielectric response due to the Goldstone mode was observed, indicating the smectic C * phase, although two switching current peaks indicative of the…
Materials used for spacecraft and space structures in near-Earth orbit are subject to severe environmental effects including high vacuum conditions, hot and cold extremes temperature, strongly oxidizing atomic oxygen environments, and high fluxes of energetic electrons, ions, neutrals and photons. Instrumentation deve…
The synthesis of Ru 2 (μ-O 2 CR) 4 (μ´-O 2 CR) (1), R = -CH 2 (CH 2 ) 6 CH=CH(CH 2 ) 5 CH 3 , has been achieved and characterization using elemental analysis and FTIR and UV-Vis spectroscopies undertaken. Strong evidence for a hexagonal discotic mesophase has been found using differential scanning calorimetry, variabl…
Abstract In contrast to earlier structure determinations of SnGa 6 Te 10 and PbGa 6 Te 10 (space group R 32), which showed disordered distributions of Sn and Pb, it could be shown for SnGa 6 Te 10 , PbGa 6 Te 10 and the new SnAl 6 Te 10 , that weak superstructure reflections can be observed in well crystallized sample…
The anionic ring-opening polymerization of six-membered cyclic carbonates having aromatic substituents, 5-methyl-5-phenyl-1,3-dioxan-2-one (1) and 5,5-diphenyl-1,3-dioxan-2-one (2), was carried out. The anionic homopolymerization of 1 readily proceeds to afford the corresponding polycarbonate, while 2 showed only a sl…
We made dielectric, magnetic and magnetoelectric studies of a hexagonal ErMnO3. Our purpose is to make clear the magnetic-electric interaction phenomena expected in this oxide with both electric and magnetic long range ordering. The magnetic-electric interaction was demonstrated as the anomalies of dielectric constant…
Composites consisting of a Ce‐TZP matrix and in‐situ grown particles of La(Fe,Al) 12 O 19 were prepared by the solid‐state reaction of Ce‐TZP, La(Fe,Al)O 3 , and Al 2 O 3 powders. The in‐situ formation process of La(Fe,Al) 12 O 19 in a Ce‐TZP matrix was investigated in relation to the microstructure evolution. The Ce‐…
Reaction of (Et 4 N)Cl with AS 2 S 3 and Na 2 S in acetonitrile at 110°C affords the polymeric thioarsenate(III) (Et 4 N) 2 As 6 S 10 in which the cyclic [As 3 S 6 ] 3- and chainlike [As 3 S 7 ] 5- trinuclear molecular building units are linked together through common sulphur atoms into infinite double chains. In cont…
Abstract Crosslink distributions in gum natural rubber (NR)/ cis -poly(butadiene) (BR) blend vulcanizates have been studied previously for cure states ranging from times shortly after the onset of cure to over-cure at 150 and 175 °C, respectively. The effects of lower cure temperatures on the crosslink distributions t…
A new nomenclature for the crystalline phases present in a sequence of structural phase transitions occurring as a function of temperature and/or pressure is dened as a rst step in presenting a unied and informative notation for the various phases appearing in a phase diagram. This nomenclature species in a compact bu…
The octamer motif (ATTTGCAT) present in several eukaryotic promoters and enhancers is now known to influence the transcription of several genes by interacting with members of a broad family of homeodomain proteins. The promoter of the human class II MHC gene HLA-DRA contains a conserved octamer element that can bind (…
Spontaneous polarization, P s , dielectric constant, ε s , and piezoelectric constant, d i j , at a given composition and temperature were calculated for all compositions of the Pb(Zr 1- x Ti x )O 3 system using phenomenological thermodynamics and compared with experimental data by considering the domain effect. In th…
We report experimental evidence for a weak first-order nematic-nematic transition in thin ( ∼ 1–2 μm) cells of the strongly polar nematogen, p -cyanophenyl p - n heptylbenzoate. The transition temperature T NN increases as the thickness of the cell decreases indicating that, in the bulk, this transition may occur at t…
The phase content of a low-density polyethylene was studied by analysis of the CH 2 rocking vibrations in non-oriented films prepared from the press (P-films) or from solution (S-films). Spectral simulations of the transmission spectra give the mass fractions of the orthorhombic phase α ortho and of two noncrystalline…
Amphoteric surfactants play an important role for the formulation of cosmetical shampoos. In recent years they find also increasing interest as for the development of dishwashing agents or household cleaners. The following article intends to demonstrate as simply as possible the chemical background of the mainly used…
Ultraviolet (UV) blocking filters are needed for atomic flux imaging in environments where high levels of ultraviolet radiation are present. Freestanding gratings are a promising candidate for UV filtering. They have a high aspect ratio (∼13), narrow (∼40 nm) slots, and effectively block UV radiation. The grating fabr…
The low frequency (LF) dielectric constant was studied as a function of temperature in the Schiff 's base liquid crystalline compounds of N (p - n -alkoxybenzylidene)- p - n -alkylanilines with the applied field parallel to the director to determine the phase transition temperatures and the underlying dipolar associat…
A surface reaction model for the catalyzed reaction A+(12)B2→AB is studied by means of Monte Carlo simulations. Motivated by experiments on the catalytic oxidation of CO on certain Pt surfaces; i.e., A≡CO, B2≡O2, and AB≡CO2; it is assumed that the catalyst surface undergoes reactant’s induced reversible phase transiti…