Macromolecular engineering of polylactones and polylactides. XXI. Controlled synthesis of low molecular weight polylactide macromonomers
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Materials Literature
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Hydrogen Absorption in Iron Exposed to Simulated Concrete Pore Solutions
Safe cathodic protection (CP) limits are required for prestressed steel in concrete to avoid the risk of hydrogen embrittlement (HE). A CP protection potential more positive than the reversible hydrogen potential is one approach for avoidance of HE. However, it has been demonstrated in the literature that the steel te…
Structural studies for ZnxMg0.8-xNi0.2Fe2O4 ferrites
A series of samples of the system Zn x Mg0.8—x Ni0.2Fe2O4 (with x=0,0.2,0.4,0.6 and 0.8), was prepared using the usual ceramic technique. The samples were studies using X-ray diffraction, DTA, TG, TGA and IR spectroscopy. The lattice constant, radius of tetrahedral ion, X-ray density and measured bulk density are foun…
Critical Pitting Potentials for Type 304 Stainless Steel in High-Temperature Chloride Solutions
The critical pitting potentials (Epit) of type 304 (UNS S30400) stainless steel (SS) were determined as a function of temperature (373 K to 523 K) and chloride (Cl−) concentration (1.00 x 10−2 mol/kg-H2O to 2.09 mol/kg-H2O [4.54 x 10−3 mol/lb-H2O to 9.48 x 10−1 mol/lb-H2O], m). Steady polarization tests were performed…
Side-chain liquid crystal copolymers containing nonmesogenic units: Dependence of the thermal behavior upon composition
The reactivity ratios have been determined for a mesogenic/nonmesogenic comonomer system, namely 5-[4-(4′-methoxyphenyl)phenoxy]pentyl methacrylate/methyl methacrylate. The reactivity ratios were found to be equal and approximately unity. The copolymerization is, therefore, azeotropic and the resulting copolymers poss…
Free radical polymerizations associated with the trommsdorff effect under semibatch reactor conditions. II: Experimental responses to step changes in temperature
Abstract Several free radical addition polymerizations exhibit the diffusion limited gel or Trommsdorff effect. The models available until recently could not be applied to industrially important semibatch operations and to nonisothermal polymerizations. The recent model of Ray et al. (24) can indeed be applied to such…
Synthesis and Characterization of Dinuclear and Tetranuclear Mixed-Spin Nickel(II) Complexes with 2,6-Bis(salicylideneaminomethyl)-4-methylphenol
Abstract Dinuclear and tetranuclear nickel(II) complexes with 2,6-bis(salicylideneaminomethyl)-4-methylphenol (H3L), [Ni2(L)(pz)(Hpz)(CH3OH)]·CH3OH (1) and [Ni4(L)2(pz)2(CH3OH)] (2) (Hpz = pyrazole), have been synthesized and characterized by infrared and electronic spectra, and by temperature dependence of magnetic s…
Scapolite cell-parameter trends along the solid-solution series
Other| February 01, 1996 Scapolite cell-parameter trends along the solid-solution series David K. Teertstra; David K. Teertstra University of Manitoba, Department of Geological Sciences, Winnipeg, MB, Canada Search for other works by this author on: GSW Google Scholar Barbara L. Sherriff Barbara L. Sherriff Search for…
X‐RAY MICROANALYSIS IN CELL BIOLOGY AND CELL PATHOLOGY
Electron probe X-ray microanalysis has been used for the last 25 years by biologists to obtain information about the distribution of elements at the cell and tissue level. During this period, progress has mainly been made through the development of more adequate techniques for specimen preparation (mainly low temperat…
Thermodynamic Assessment of the Zirconia‐Urania System
An optimal thermodynamic data set for the zirconia‐urania system is evaluated by the CALPHAD (CALcula‐tion of PHAse Diagrams) method. A regular solution model is applied to all phases of the cubic, tetragonal, and mono‐clinic solid solutions and the liquid. Comparisons between calculated and measured phase diagrams sh…
Aromatic and rigid rod polyelectrolytes based on sulfonated poly(benzobisthiazoles)
Aromatic polyelectrolytes based on sulfonated poly(benzobisthiazoles) (PBTs) have been synthesized by a polycondensation reaction of sulfo-containing aromatic dicarboxylic acids with 2,5-diamino-1,4-benzenedithiol dihydrochloride (DABDT) in freshly prepared polyphosphoric acid (PPA). Several sulfonated PBTs, poly[(ben…
Ring-opening polymerization of macrocyclic aryl ether ketone oligomers containing the 1,2-dibenzoylbenzene moiety
Facile ring-opening polymerization of cyclic aryl ether oligomers containing the 1,2-dibenzoylbenzene moiety to form high molecular weight linear polymers in the presence of a nucleophilic initiator is described. The polymerization can be initiated in the melt in the presence of a nucleophilic initiator such as potass…
Cooperative relaxations in semicrystalline fluoropolymers studied by thermally stimulated currents and ac dielectric
Semicrystalline fluoropolymers including poly(tetrafluoroethylene) (PTFE), a 8 mol % hexafluoropropylene (HFP)/92% TFE random copolymer (FEP), and poly(vinyl fluoride) (PVF) were studied using thermally stimulated current depolarization (TSC), ac dielectric, and other thermal analysis techniques. The TSC thermal sampl…
Synthesis and properties of aromatic polyamides derived from 1,7-bis(4-aminophenoxy)naphthalene and various aromatic dicarboxylic acids
A series of novel bis(phenoxy)naphthalene-containing polyamides having inherent viscosity up to 2.02 dL/g were synthesized by the direct polycondensation of the diamine 1,7-bis(4-aminophenoxy)naphthalene with various aromatic dicarboxylic acids in N-methyl-2-pyrrolidone (NMP) using triphenyl phosphite and pyridine as…
Concrete Penetration by Eroding Projectiles: Experiments and Analysis
Spherical-nose copper and tantalum rods with aspect ratios between 4.0 and 14.6 were gun launched against 91-cm-diameter and 91-cm-long concrete and simulant reinforced-concrete targets with velocities ranging from 0.15 cm/μs to 0.19 cm/μs. Targets were instrumented with a sequence of break gauges that provided valuab…
An FTIR Study of Water Sorption on TMA- and TMPA-Montmorillonites
Abstract Water inhibits sorption of uncharged organic compounds on montmorillonites saturated with small alkylammonium cations such as tetramethylammonium (TMA) and trimethylphenylammonium (TMPA). As a first step toward understanding the mechanism by which water inhibits arene sorption on TMA- and TMPA-montmorillonite…
Reverse Monte Carlo modeling of amorphous germanium
The reverse Monte Carlo (RMC) method has been used to generate a model for the atomic structure of amorphous germanium (a-Ge). Fitting to experimental neutron diffraction data and applying coordination number and ``triplet'' constraints, the positions of 3000 ``atoms'' in a box, with full periodicity, were altered unt…
Structure of ζ-phase plutonium–uranium
The structure of the ζ-phase in the Pu—U system has been determined by neutron powder diffraction. The phase crystallizes in space group R {\bar 3} m with 58 atoms in the primitive unit cell and 10 atoms in the asymmetric unit. The structure is characterized by many short bonds and fits the general pattern of the ligh…
Site-selective excitation and polarized absorption spectra of Nd3+ in Sr5(PO4)3F and Ca5(PO4)3F
Polarized absorption and fluorescence spectra were analyzed to establish individual energy (Stark) levels of Nd3+ ions in host crystals of Sr5(PO4)3F (SFAP) and Ca5(PO4)3F (FAP). Site-selective excitation and fluorescence facilitated differentiation between Nd3+ ions in emitting sites associated with 1.06 μm stimulate…
Modified Atmosphere Packaging of Fresh Beansprouts
Freshly harvested beansprouts displayed a respiration rate of about 1 mmol O2 kg−1 h−1 at 10°C which was strongly dependent on temperature, a 10-fold increase being observed every 16·5°C (z=16·5°C, ie Q10=4·4). This commodity is also characterised by a high initial microbial load (about 107 cells g−1). During storage…