Materials Literature
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The synthesis and a preliminary structural characterization of syndiotactic poly( m -methylstyrene) are reported. A complex polymorphic behavior has been revealed. Three different polymorphic forms and two clathrate structures, characterized by the inclusion of guest molecules in the crystalline lattice, have been fou…
To furnish new insight into structure−property relationships governing glassy nematic liquid crystals, novel material systems were synthesized and characterized. Highly ordered, solid films were also prepared via spin-coating for the determination of optical birefringence. It was found that a linear nematogen, such as…
The field-dependent low-temperature specific heat of an optimally doped polycrystalline sample of ${\mathrm{La}}_{0.65}{\mathrm{Ca}}_{0.35}{\mathrm{MnO}}_{3}$ ${(T}_{C}=265\mathrm{K}),$ $1<~T<~32\mathrm{K}$ and $0<~H<~9\mathrm{T}$ was analyzed by a global least-square fit to separate the hyperfine, electro…
Abstract The rheological behavior of polypropylene, PP, ethylene‐propylene copolymer, EPR, and EPR/PP blends was studied. Zero‐shear viscosity and elastic relaxation time were determined by least‐squares fits by using a Carreau–Yasuda model with Arrhenius temperature dependency. The effect of PP and EPR molecular weig…
Abstract The average rubber particle size, size distribution, and matrix ligament thickness between particles in polypropylene blends containing metallocene catalyzed ethylene–octene copolymers have been quantitatively analyzed, as functions of blend composition and phase viscosity ratio. Comparison has been made betw…
Abstract The effect of processing conditions and elastomer content on the toughening of Polypropylene (PP) by melt blending with styrene/ethylene‐butylene/styrene tri‐block copolymer (SEBS) in a twin‐screw extruder has been investigated. The parameters analyzed were: temperature profile, screw speed, and feed rate of…
Nanoscale dispersion of only a few weight percentage of layered silicate (montmorillonite) in nylon 6 and epoxy results in the formation of a uniform passivating and self-healing inorganic surface region upon exposure to oxygen plasma. The enrichment of inorganic is compositionally graded with respect to the surface a…
X-ray magnetic-circular-dichroism (XMCD) spectra on the molecular superparamagnets $[{\mathrm{Mn}}_{12}{\mathrm{O}}_{12}{(\mathrm{C}\mathrm{H}}_{3}{\mathrm{C}\mathrm{O}\mathrm{O})}_{16}{(\mathrm{H}}_{2}{\mathrm{O})}_{24}]\ensuremath{\cdot}{2\mathrm{C}\mathrm{H}}_{3}{\mathrm{COOH}\mathrm{\ensuremath{\cdot}}4\mathrm{H}}…
A series of analyses were performed on fibrin-based adhesives to describe their failure characteristics. Two test methods were used: uniaxial, monotonic tensile testing of the bulk material, and blister testing using fresh porcine-source skin graft as the adherend. Two fibrin concentrations, high (HFC), and low (LFC),…
ZSM-5 crystals and glass plates tethered with trimethylpropylammonium iodide and sodium butyrate, respectively, (denoted as Z+, Z-, G+, and G-, respectively) were prepared. Treatment of G- with Z+ suspended in ethanol results in monolayer assembly of Z+ on G- (G-/Z+) with high surface coverage. The zeolite crystals ha…
Transparent organic−inorganic hybrid material was synthesized via the sol−gel method using polyethylene- co -Zn-acrylic acid (Zn−PEAA) ionomer and a metal alkoxide, tetraethyl orthosilicate (TEOS). The resulting material was characterized using various spectroscopic, microscopic, and thermal techniques. Photoacoustic…
The self-polarization effect in ferroelectric thin films has been studied for PZT films 0.5-1 µm thick deposited by radio-frequency magnetron sputtering of various ferroelectric ceramic targets (Zr/Ti = 54/46, Zr/Ti = 54/46 + 10% PbO and Zr/Ti = 40/60 + 10% PbO). The laser intensity modulation method has been applied,…
The boride compounds MB_x related to the magnesium-boron stacking layered material MgB2 are discussed in terms of the B-B layers in the borides analogous to the Cu-O ones in the cuprates. We propose a possibility of superconducting materials which exhibit higher critical temperature T_c than 39 K of MgB2. We point out…
A Schwinger boson mean field theory is developed for spin liquids in a symmetric spin-orbital model in higher dimensions. Spin, orbital and coupled spin-orbital operators are treated equally. We evaluate the dynamic correlation functions and collective excitations spectra. As the collective excitations have a finite e…
The sputtering yield, Y, from a cylindrical thermal spike is calculated using a two dimensional fluid dynamics model which includes the transport of energy, momentum and mass. The results show that the high pressure built-up within the spike causes the hot core to perform a rapid expansion both laterally and upwards.…
Self-organization on crystal surface is studied as a two dimensional spinodal decomposition in presence of a surface stress. The elastic Green function is calculated for a $(001)$ cubic crystal surface taking into account the crystal anisotropy. Numerical calculations show that the phase separation is driven by the in…
The density and the elastic stiffness coefficients of fcc solid argon at high pressures from 1 GPa up to 80 GPa are computed by first-principles pseudopotential method with plane-wave basis set and the generalized gradient approximation (GGA). The result is in good agreement with the experimental result recently obtai…
We study the transverse cracking of the 90 degree ply in [0/90] cross-ply laminates by means of a discrete element method. To model the 90 degree ply a two-dimensional triangular lattice of springs is constructed where nodes of the lattice model fibers, and springs with random breaking thresholds represent the disorde…
The morphology of multilayer films formed from polydiallyldimethylammonium chloride and polystyrene sulfonic acid deposited under a range of salt concentrations (from 10 - 4 to 1.0 M) was investigated using atomic force microscopy (AFM). Ten-bilayer films that were deposited with less than 0.3 M added NaCl were flat a…
Extended x-ray absorption fine-structure measurements have been performed on ZnSe crystals doped with Er by an addition of ErF 3 during growth. The results show that Er exists in these samples in an orthorhombic configuration with nine nearest F neighbours similar to that in orthorhombic ErF 3 . The energy level split…