Materials Literature
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Hydroxyl terminated natural rubber (HTNR) was prepared by the depolymerization of masticated natural rubber in the presence of H2O2 in toluene. Probable mechanisms leading to the formation of side reaction products are proposed based on the analytical data. A comparative study of some formulation variables was made fo…
The effect of an electric field on the measured order parameter of a liquid crystal is considered. It is pointed out that an external field may influence the apparent degree of order by changing the microscopic order parameter, and by quenching director fluctuations. In nematic liquid crystal the latter dominates, but…
(TMPTF)2SbF6 shows an anomaly on the temperature dependence of its electrical conductivity at 154K and at low temperature an antiferromagnetic ground state. On the other hand (TMTTF)2AsF6 ground state is non-magnetic. He present the spectroscopic and magnetic studies of these two salts and of their alloys (TMTTF)2 (Sb…
The origin of the dark region in LPE grown GaP crystals associated with macrostep is investigated by observation of photoluminescence (PL) image and spatially resolved photolumenescence (SRPL) spectroscopy. PL image from the cleaved surface of undoped, N, S, and Zn doped layers showed that the dark region appeared onl…
Abstract Bubble distribution in shaped sapphire crystals grown by Stepanov technique is found to depend on the field of velocities of the melt flows between the top surface of a die and the crystallization front. A die design defining the flows in the meniscus is a tool for control over the bubble distribution.
Three luminescence transitions in the 476 nm excited spectrum of Cs2NaTmCl6 between 7200–4100cm-1 are assigned to the 3 H 4 → 3 F 4, 3 H 5 and 3 F 4 → 3 H 6 transitions of TmCl3- 6. A crystal field analysis of the energy levels of this anion is given.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and characterization of model urethane compoundsZ. Y. Qin, C. W. Macosko, and Stephen T. WellinghoffCite this: Macromolecules 1985, 18, 3, 553–557Publication Date (Print):March 1, 1985Publication History Published online1 May 2002Published inissue 1 March 1985https…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiffusion of dye molecules in polymers above and below the glass transition temperature studied by the holographic grating techniqueJochen Coutandin, D. Ehlich, Hans Sillescu, and Chin Hsien WangCite this: Macromolecules 1985, 18, 3, 587–589Publication Date (Print):March 1,…
Meridional x-ray reflections of Kevlar (TM) aramid fibers have been analyzed to provide direct information about fine structure in the direction of the fiber axis. In particular, these reflections have been studied to provide evidence for a one-dimensional paracrystalline structure in Kevlar and to seek quantitative s…
Abstract The infrared reflectivity spectra polarized along the c ‐axis of potassium dihydrogen phosphate are studied for both, the ferro‐ and paraelectric phase, over a wide temperature range: 10 to 420 K. The reflectivity spectra are fitted to the factorized form of the dielectric function. The temperature dependence…
Abstract (NEt4)2[Ni(SPh)4], (NEt4)3[Ni3(SEt)12] and (NEt4)2[Ni2(edt)3] (edt=ethan-1,2-dithiolate dianion), were synthesized by a simple method. These complexes were condensated stepwise by controlled protolysis through their own higher clusters such as [Ni(SEt)2]n(n≠∞) and (NEt4)2[Ni3(edt)4] to the polymers, [Ni(SPh)2…
Abstract A very simple method to get the same structural weights as those provided by a fully correlated valence bond function is proposed. It applies to the ground states of delocalized systems, and only requires the knowledge of the occupied molecular orbitals. The SCF wavefunction is projected on a valence bond bas…
A tentative phase diagram for the system Al 2 0 3 ‐Nd 2 O 3 is presented. Three compounds were obtained: a β ‐A1 2 O 3 ‐type compound, the perovskite NdAlO 3 , and Nd 4 Al 2 O 9 . The perovskite melts congruently (mp 2090°C), and the two other compounds exhibit incongruent melting behavior: β ‐Nd/Al 2 O 3 , mp 1900°C;…
Diagrams with the c/a ratio as ordinate and cos (180° - β) as abscissa are given, which allow one to find out how a given monoclinic unit cell can be transformed so that a and c are the shortest translation vectors compatible with the symmetry of the space group in a setting corresponding to the standard space-group s…
Details of valve morphology are used to differentiate between Tabellaria quadriseptata Knudson and T. flocculosa (Roth) Kütz. in cleaned material. Results substantiate Knudson's species description of T. quadriseptata. Characteristics used to separate the two species are valve shape, nature of marginal spines, and loc…
Abstract Our preliminary investigations indicate that recycled rubber crumb may be used as a toughening agent for brittle thermoplastic such as polystyrene. The toughness of the resultant materials was found to increase with increasing rubber-to-matrix adhesion and decreasing particle size. Although crazing is expecte…
Abstract The bubble growth in polymeric fluids under nonisothermal conditions has been molded using the viscoelastic constitutive equation of Leonov incorporating the diffusion of gas from the melt to the bubbles. The gas diffusion seems to be the primary mechanism of bubble growth. The theoretical predictions for Han…
The reflection and refraction of light of wavelength lambda at an angle of incidence Phi by the interface between two dielectric media of refractive indices N(0) and N(2) can be made completely independent of polarization by introducing a thin layer of refractive index N(1) = (N(0) N(2))(1/2) and thickness d = (lambda…
The method of preirradiation grafting of acrylic acid and methacrylic acid onto polyethylene films was studied. The trapped radicals and hydroperoxides or diperoxides appeared to be able to induce graft polymerization. Mohr's salt was added to depress homopolymerization. The influences of crystallinity, dosage, and st…
A simple model which accounts for the effects of the electron-molecular vibration (e-mv) interaction on the vibrational spectra of regular mixed stack charge-transfer complexes is presented and compared with that working for dimerized mixed stack compounds. The proposed interpretative scheme makes the spectra a powerf…