Materials Literature
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The kinetics and mechanisms of polymerization of equifunctional 4,4'-(N,N'-bismaleimide)-diphenylmethane/2,2'-diallyl-bisphenol A (BMDM/DABPA) and model (phenylmaleimide/2-allylphenol) (PMI/AP) systems have been studied in the temperature range 140 – 400 °C using IR-, 1H and 13C NMR spectroscopy, GC/MS, DSC, and isoth…
Nylon 1010 crystals with different size and perfection were prepared under various crystallization conditions. Temperature-varied X-ray diffraction and transmission electron microscopy were used to investigate the structure and morphology of these crystals. The pseudo-hexagonal phase (also known as γ modification) of…
This paper presents the study on lithium triborate glass (LBO) in the system (1-x)|3B2O3.Li2O| (x)Nb2O5 yPr3+ zYb3+ wNd3+ with 0 £ x £ 20 mol% (y, z and w in mol%). The samples were studied by Raman spectroscopy, infrared absorption and differential thermal analysis. Pr3+-doped LBO and Pr3+/Yb3+-doped LBO samples show…
Examination of a wide range of experimental data relating to 'low-loss' dielectric materials reveals the little acknowledged fact that their loss at high frequencies (kHz to GHz) and low temperatures (typically 100 to 200 K) is weakly or very weakly dependent on frequency, what we call 'flat loss', and is likewise wea…
O trabalho abordou a formação de solos com horizonte B textural e teve por objetivo identificar os processos pedogenéticos envolvidos na formação de lamelas, do gradiente textural abrupto, assim como suas implicações sobre os atributos físicos, químicos e mineralógicos do solo. O estudo foi desenvolvido numa toposseqü…
A new organic ionic crystal of 4-(dimethylamino)-1-ethylpyridinium iodide (DMAEPI) was synthesized for use in second-order nonlinear optics, and its crystal structure was found to belong to the orthorhombic space group Pmn2 1 . This crystal is considered to be a promising candidate for frequency conversion of diode la…
The opto-mechanical effect observed in amorphous chalcogenide films deposited onto clamped STM cantilevers 1 has been investigated. In this, bandgap light, incident on the chalcogenide film and linearly polarized either parallel or perpendicular to the cantilever axis, reversibly causes respectively either a contracti…
Magnetization experiments were performed on a series of single crystals of the bilayer manganites La2−2xSr1+2xMn2O7. The magnetic anisotropy constants were determined by fitting expressions based on the tetragonal anisotropy energy to the magnetization curves. It is shown that there is a significant dipolar contributi…
Perovskite type-materials LaCo (1-x) Fe x O 3 were prepared from their component oxides using mechano-synthesis, a new method of preparation designated as reactive grinding. When grinding additives are used, the perovskites generated via this process are of unprecedently high specific surface area (>100 m 2 /g) and th…
Abstract In this paper, we describe a new method to manufacture cholesteric colour filters. The cholesteric colour filter is made by a simple method, comprising one coating step and two UV exposure steps. The optical performance of the cholesteric colour filter and a reflective LCD with a cholesteric colour filter ins…
Interests in the use of borate crystals in ultraviolet nonlinear optics have increased because all-solid-state UV lasers obtained with NLO crystals are in highly demand for scientific and industrial applications. Recently, new borate crystals, CsLiB 6 O 10 and Gd x Y 1-x Ca 4 O ( BO 3 ) 3 have been developed by the pr…
The role of cyclization in polycondensations is discussed for two different scenarios: thermodynamically-controlled polycondensation (TCPs) on the one hand and kinetically-controlled polycondensations (KCPs) on the other. The classical Carothers–Flory theory of step-growth polymerization does not include cyclization r…
Homogeneous, fine grained (≈ 0·5–2 µm), and dense (≥ 97% of theoretical density) alumina–mullite composites have been prepared by a colloidal filtration route. In order to improve the uniformity of the composites, the rheological behaviour of aqueous suspensions of alumina, mullite, and alumina–mullite mixtures was st…
The application of long fibre reinforced thermoplastics has been mainly limited to the automotive industry where large production runs offset the high
${\mathrm{Pr}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ and ${\mathrm{Nd}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ were investigated with three-photon difference frequency generation (DFG). This method allows one to determine both the crystalline and the magnetic symmetry. In the highly or…
A temperature-controlled Couette-type shear system has been designed and constructed allowing in situ the simultaneous neutron scattering and the optical microscopy study of the nonequilibrium states of thermotropic complex fluids subjected to a steady-state shear flow. In contrast to the usual neutron Couette devices…
Wir haben die Systeme CuGa5S8/CuIn5S8 und AgGa5S8/AgIn5S8 an abgeschreckten Präparaten mit Röntgenpulver- und Einkristallmethoden untersucht. Im System AgGaxIn5–xS8 wird bis x < 2 eine Phase mit Spinellstruktur gebildet. Für 2 < x ≤ 3 existiert eine Phase, die in einer hexagonalen Schichtstruktur kristallisiert. Die S…
The mechanical properties of a ternary system consisting of low density polyethylene (LDPE), poly(ethylene-co-methacrylic acid) copolymer (EMAA) and wood flour (WF) were investigated. For a better understanding of the mutual interactions between the components, binary blends LDPE/EMAA and EMAA/WF were studied as well,…
Syndiotactic polystyrene (sPS) of a low molecular weight (M̄w = 63 000 g/mol) was found to develop only a β-type unit cell upon melt crystallization at all temperatures. Correlation between the lamellar morphology and melting behavior in the sPS has been demonstrated in this study. When crystallized at lower temperatu…
The effect of excess lead oxide on the microstructure and ferroelectric properties of lead zirconate titanate (PZT) films was studied in PZT-based thin-film capacitor structures. It is shown that excess lead in the form of lead oxide is localized at the grain boundaries and film-platinum electrode interfaces, which ca…