Materials Literature
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Abstract This article describes the structure and electrical performance of positive‐temperature‐coefficient/negative‐temperature‐coefficient (PTC/NTC) effects of the following three‐component blends: poly(4‐methyl pentene‐1)/ultra‐high molecular weight polyethylene/carbon black (TPX/UHMWPE/CB), poly(4‐methyl pentene‐…
The in vitro hydrolytic degradation of thin (ca. 100 μm) films of poly(glycolic acid) (PGA) has been studied, focusing on the kinetics of degradation of the near surface phases. The emphasis of this work is to describe the nature of the initial “induction” period of hydrolysis of biodegradable polyesters, where water…
We report high-resolution angle resolved photoemission studies of $2H\ensuremath{-}{\mathrm{NbSe}}_{2}$ and $2H\ensuremath{-}{\mathrm{TaS}}_{2}.$ Results are compared to those of $2H\ensuremath{-}{\mathrm{TaSe}}_{2}.$ We find that the normal state electronic structures in this family of materials have the same basic c…
Monodispersed poly( l -lactide)- block -poly(oxyethylene) (PLLA−PEG) and poly( l -lactide)- block -poly(oxyethylene)- block -poly( l -lactide) (PLLA−PEG−PLLA) were synthesized, and their nanoparticles were successfully prepared in an aqueous medium. Both particles of the di- and triblock copolymers were nanoscale in s…
Abstract Blend films of poly( L ‐lactide) (PLLA) and poly(vinyl alcohol) (PVA) were obtained by evaporation of hexafluoroisopropanol solutions of both components. The component interaction, crystallization behavior, and miscibility of these blends were studied by solid‐state NMR and other conventional methods, such as…
Structural characterization of a fully etched amorphous W/Si multilayer grating with a lateral periodicity of 800 nm is performed by x-ray reflectivity in the coplanar and non-coplanar modes using a scintillation detector and a two-dimensional gas-filled detector, respectively. Three-dimensional reciprocal space const…
The templating of the ordered nanostructures of lyotropic liquid crystals (LLC) onto organic polymers has recently been of great interest. This work describes the polymerization and segregation behavior of polar and nonpolar monomers in an LLC environment. Nonpolar monomers partition to the oil-soluble domains of the…
Abstract The rheological and electric properties of blends of poly(ethylene terephthalate) (PET) and high‐density polyethylene (HDPE) filled with various types of carbon black (CB) were analyzed in detail in this project. Four types of CB samples with available values of surface area, particle size, porosity, density,…
The dilute-solution dynamical properties of dendrimers in a good solvent are derived in the framework of the Rouse−Zimm approach. On the basis of a normal-coordinates treatment with preaveraged hydrodynamic interaction, we obtain the spectrum of relaxation times and some dynamical observables such as the viscoelastic…
Abstract The effects of crosslink structures on the dynamic mechanical properties (DMPs) of unfilled and carbon black N330‐filled natural rubber (NR) vulcanizates cured with conventional (CV), semiefficient (SEV), and efficient (EV) cure systems and having about the same total crosslink densities were investigated bef…
Abstract The effect of plasma treatment on the surface characteristics and conductivity of polyaniline–nylon 6 composite fabrics was investigated. Plasma surface modifications with oxygen, ammonia, and argon were performed on the nylon 6 fabrics to improve the adhesion and rate of polymerization. The surface morpholog…
Abstract The effect of the filler volume fraction on the tensile behavior of injection‐molded rice husk‐filled polypropylene (RH–PP) composites was studied. Hygrothermal aging behavior was also investigated by immersing the specimens in distilled water at 30 and 90°C. The kinetics of moisture absorption was studied fr…
Dithienylethene-bridged diporphyrins 1-6 were prepared as photochemical switching molecules. Porphyrin and dithienylethene are directly linked in 1, and linked, respectively, through a 1,4-phenylene spacer in 2, through a 4-ethynylphenylene spacer in 3, and through a di-4-phenylethynylene spacer in 4, while meso-ethyn…
For several years the ESRF, the University of the Witwatersrand and De Beers Industrial Diamonds (PTY) Ltd through their Diamond Research Laboratories have pursued a development programme to improve the quality of synthetic diamond crystals. Recently, in an effort to study the influence of nitrogen impurities on the d…
We have studied the structural and superconducting properties of MgB$_2$ thin films made by pulsed laser deposition followed by in situ annealing. The cross-sectional transmission electron microscopy reveals a nanocrystalline mixture of textured MgO and MgB$_2$ with very small grain sizes. A zero-resistance transition…
The viscoplastic deformation (creep) of crystalline materials under constant stress involves the motion of a large number of interacting dislocations. Analytical methods and sophisticated `dislocation-dynamics' simulations have proved very effective in the study of dislocation patterning, and have led to macroscopic c…
We present a lattice model to study the equilibrium phase diagram of ordered alloys with one magnetic component that exhibits a low temperature phase separation between paramagnetic and ferromagnetic phases. The model is constructed from the experimental facts observed in Cu$_{3-x}$AlMn$_{x}$ and it includes coupling…
A relatively high critical temperature, Tc, approaching 40 K, places the recently-discovered superconductor magnesium diboride (MgB2) intermediate between the families of low- and copper-oxide-based high-temperature superconductors (HTS). Supercurrent flow in MgB2 is unhindered by grain boundaries, unlike the HTS mate…
We have performed high resolution x-ray photoemission spectroscopy experiments on the Ru(0001) surface, both clean and covered with well-defined amounts of oxygen up to 1 monolayer coverage. For the clean surface we detected two distinct components in the Ru ${3d}_{5/2}$ core-level spectra, for which a definite assign…
A theoretical study of the ring-opening polymerization (ROP) mechanism of 1,5-dioxepan-2-one (DXO) and l -lactide (LLA) with stannous(II) 2-ethylhexanoate (Sn(Oct) 2 ) is presented. The B3LYP density functional method has been used for the quantum chemical calculations. Our results support a coordination−insertion mec…