Materials Literature
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For some applications for fluoropolymers they must be subjected to high-energy radiation, e.g., when they are grafted with styrene using an irradiation method to produce fuel cell membranes or matrix supports for combinatorial chemistry. In some of these applications they may be subjected to mechanical stress or eleva…
The enthalpy recovery mechanism of polymers is usually described in terms of the Tool−Narayanaswamy−Moynihan model (TNM). Even if it is able to qualitatively reproduce all the peculiar features of the aging process, clear discrepancies have been found in quantitative analysis. In this work, differential scanning calor…
We present excitation-energy dependent Raman measurements between 2.05 and 2.41 eV on the same individual carbon nanotube. We find a change in the Raman frequencies of both the $D$ mode ($63\text{ }\text{ }{\mathrm{c}\mathrm{m}}^{\ensuremath{-}1}/\mathrm{e}\mathrm{V}$) and the high-energy modes. The observed frequenci…
Large-scale synthesis of arrays of high-aspect-ratio rigid vertically aligned carbon nanofibres, Melechko, A V, McKnight, T E, Hensley, D K, Guillorn, M A, Borisevich, A Y, Merkulov, V I, Lowndes, D H, Simpson, M L
Abstract Nanoporous polyimide films were prepared in two steps. The first step is the preparation of poly(urethane‐imide) films by casting blend solutions containing various weight percentages of poly(amic acid) and phenol blocked polyurethane prepolymer (from 1,6‐hexamethylene diisocyanate and poly(ethylene glycol)).…
Laser photolysis at 193 nm of gaseous carbon disulfide into CS and S in the absence and excess of N 2 is controlled by two-photon-induced depletion of CS 2 and affords chemical vapor deposition of (CS) n polymer and S n . The proposed polymerization mechanism of CS is explained by an intermediacy of C 2 S 2 species. T…
Abstract Triblock copolymers and pentablock terpolymers of n ‐hexyl isocyanate (H), styrene (S), and isoprene (I) of the type HSH (six samples, M n :49–163 K, weight % of H:5–59), HIH (two samples, M n :75 and 83.4 K, weight % of H:16 and 40), HSISH (one sample, M n :79.4 K, weight % of H:13), and HISIH (one sample, M…
In this paper we present the electrochemical etching characteristics of a shape memory alloy (SMA) using new electrolytes of inorganic salt in alcohol, in comparison with conventional H 2 SO 4 –methanol solution. It has become apparent that pattern etching of SMA sheets can be carried out in electrolyte solutions usin…
The initial stages of aggregation of a series of organogelator salts, prepared from n -alkylamines by the rapid in situ and isothermal (at room temperature) uptake of the neutral triatomic molecule, CO 2, have been probed by NMR spectroscopy in the nongelled liquid, chloroform- d . Evidence for specific interactions o…
A seismic-resistant member with a shape memory alloy (SMA) rod was used in an exposed-type column base as a passive damper for building structures. Horizontal and vertical loading tests on the column base with SMA anchorage were done with increasing drift amplitude to investigate the restoring force characteristics of…
Pt nanoparticles (Pt n ) and their agglomerates (Pt n ag ) were synthesized by chemical reduction methods. The mean sizes of Pt n and Pt n ag were determined to be respectively 3.4 and 400 nm using transmission electron microscopy (TEM). CO adsorption on electrodes made of the two kinds Pt nanomaterials was used as th…
We report here the synthesis and characterization of two new classes of chelating fibers, namely, (1) polymercaptopropylsilsesquioxane (PMPS) and (2) copper(II) ferrocyanide complexed with poly[1-(2-aminoethyl)-3-aminopropyl]silsesquioxane (Cu-FC-PAEAPS) fibers. These fibers were evaluated for selective removal of tra…
Abstract The copolymerization of divinylbenzene (DVB) and ethylstyrene (EtSt) was carried out at 70 and 80 °C in benzene with dimethyl 2,2‐azobisisobutyrate (MAIB) at high concentrations as initiator in the presence of methyl benzyloxyiminoacetate (MBOIA), a glyoxylic oxime ether, as a retarder. The copolymerization s…
Abstract The effects of heat treatment on the crystal structure and impact strength of poly(phenylene sulfide) (PPS) and nano‐SiO x / PPS nanocomposites were studied. The molecular weight of heat‐treated neat PPS was increased by 28% due to the crosslinking reaction that changed its crystal morphology. Also, the cryst…
The chiral recognition in the formation of hydrogen-bonded (HB) dimers of 1,6a-dihydropyrrolo[2,3-b]pyrrole derivatives as well as in their proton-transfer processes have been studied by means of ab initio calculations. The heterochiral dimers are in general the most stable ones, but amphiprotic substituents that are…
We have determined from first principles the Curie temperature in the diluted magnetic semiconductor $({\mathrm{Ga}}_{1\ensuremath{-}x\ensuremath{-}y}{\mathrm{Mn}}_{x}{\mathrm{As}}_{y})$ As alloys, where the compensation effect by As antisites is taken into account. The disorder due to random positions of Mn impuritie…
Thin epitaxial films of MnAs--promising candidates for the spin injection into semiconductors--are well known to undergo simultaneously a first-order structural and magnetic phase transition at 10-40 degrees C. The evolution of stress and magnetization of MnAs/GaAs(001), both measured quantitatively with our cantileve…
In this work, the influence of an internal electric field upon the crystallization of lysozyme and thaumatin is explored using a modified design of the gel-acupuncture setup. From a crystallographic point of view, the orientation of crystals that grow preferentially over different types of electrodes inside capillary…
A technique for automatically evaluating microbatch (400 nl) protein-crystallization trials is described. This method addresses analysis problems introduced at the sub-microlitre scale, including non-uniform lighting and irregular droplet boundaries. The droplet is segmented from the well using a loopy probabilistic g…
Shape Memory Alloys (SMA) exhibit stable superelasticity between a reverse transformation finish temperature (A<sub>f</sub>) and approximately 30°C above A<sub>f</sub>, and therefore can sufficiently work as a superelastic material for structural use in building under the temperature in a construction environment.…