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On the determination of the molecular weight distribution of poly(dimethyl diallyl ammonium chloride) by ultracentrifugation

G. J. Timofejeva、S.A. Pavlova、C. Wandrey 等 7 位作者1990-09-01Acta Polymerica

Abstract Molecular weight distributions of poly(dimethyl diallyl ammonium chloride) were determined from sedimentation velocity measurements. After a presentation of the experimental basis for the evaluation of distribution curves, molecular weight distribution curves for different samples were discussed and compared…

Polymer Nanocomposites and PropertiesPolymer Science and PVCPolymer Science and Applications

The nonlinear dynamics of solidification of a binary melt with a quasi-equilibrium mushy region

Yu.A. Buyevich、L.Yu. Iskakova、V. V. Mansurov1990-09-01Canadian Journal of Physics

A mushy region (a two-phase zone) between the solid and liquid phases occurs often in the process of solidification of a binary melt. An analysis of the structure of the mushy region, which includes the liquid, solid particles, and dendrites extending from the bulk solid surface, is suggested. The processes of heat an…

Solidification and crystal growth phenomenaMaterial Science and Thermodynamics

Effect of metal stearate stabilizers on the thermal degradation of PVC in solution: The reversible blocking mechanism of stabilization

Béla Iván、B. Turcsányi、Tibor Kelen 等 4 位作者1990-09-01Journal of Vinyl Technology

Abstract Systematic thermal degradation studies of PVC solutions have been carried out in the presence of different metal carboxylates (Pb‐, Cd‐, Ba‐, Ca‐ and Zn‐ stearates). ZnSt 2 markedly accelerates degradation of the polymer. Significant induction periods ( t i ) for the appearance of free HCI are obtained in the…

Advanced Polymer Synthesis and CharacterizationExtraction and Separation ProcessesPolymer Science and PVC

Synthesis and characterization of alkaline-earth indium sulfides

D. O. Kipp、C. K. Lowe‐Ma、Terrell A. Vanderah1990-09-01Chemistry of Materials

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and characterization of alkaline-earth indium sulfidesD. O. Kipp, C. K. Lowe-Ma, and T. A. VanderahCite this: Chem. Mater. 1990, 2, 5, 506–511Publication Date (Print):September 1, 1990Publication History Published online1 May 2002Published inissue 1 September 1990h…

Solid-state spectroscopy and crystallography

Unified theory of effects of segregated interstitials on grain boundary cohesion

Alan Cottrell1990-09-01Materials Science and Technology

The ideas of the electron theory of chemisorption are applied to the behaviour of H, B, C, N, and 0 atoms segregated on and in iron. The general theory can be divided naturally into two branches depending on whether the valence levels of the embedded atoms ‘float’ at the Fermi level, as in the case of B, C, and N; or…

Microstructure and mechanical propertiesFusion materials and technologiesHydrogen embrittlement and corrosion behaviors in metals

Angular Distribution of Elastically Reflected Electrons from Au

Zejun Ding、Hideki Yoshikawa、Ryōsuke Shimizu1990-09-01physica status solidi (b)

Abstract The angular distributions of elastically reflected electrons from an evaporated gold film surface are measured at primary energies 400, 600, and 800 eV for different angles of incidence between 0° and 75°, and the influence of 2 keV Ar + ion bombardment is investigated. By means of Monte Carlo simulations the…

Electron and X-Ray Spectroscopy TechniquesIon-surface interactions and analysisSurface and Thin Film Phenomena

Impact behavior of modified PVC for outdoor applications

Ampere A. Tseng、M. A. Borrosky、Steve O’Connor 等 4 位作者1990-09-01Advances in Polymer Technology

Abstract A systematic study was conducted to determine the optimum polyvinylchloride (PVC) molecular weight and impact modifier concentration blend for the construction or outdoor application. This application called for a material with superior impact and weathering properties as well as cost efficiency. Three differ…

Polymer crystallization and propertiesNatural Fiber Reinforced CompositesPolymer Science and PVC

Three Pentacyclic Triterpenoids from the Leaves of Plumeria obtusa

Salimuzzaman Siddiqui、Bina S. Siddiqui、Akhtar Naeed 等 4 位作者1990-09-01Journal of Natural Products

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThree Pentacyclic Triterpenoids from the Leaves of Plumeria obtusaSalimuzzaman Siddiqui, Bina Shaheen Siddiqui, Akhtar Naeed, and Sabira BegumCite this: J. Nat. Prod. 1990, 53, 5, 1332–1336Publication Date (Print):September 1, 1990Publication History Published online1 July 2…

Natural product bioactivities and synthesisPhytochemistry and Biological ActivitiesPhytochemistry and Bioactive Compounds

Kinetics and mechanism of oxidation of iodide ion by the molybdenum (VI) – hydrogen peroxide system

Conchita Arias、Fernando Mata、Joaquin F. Perez‐Benito1990-09-01Canadian Journal of Chemistry

The kinetics of oxidation of potassium iodide by hydrogen peroxide in aqueous perchloric acid has been studied both in the absence and in the presence of sodium molybdate by means of the initial-rates method. The law found for the total initial reaction rate is[Formula: see text]The activation energies associated with…

Inorganic and Organometallic ChemistryThermal and Kinetic Analysis

Crosslink Distribution and Interfacial Adhesion in Vulcanized Blends of NR and NBR

Andrew Tinker1990-09-01Rubber Chemistry and Technology

Abstract In contrast to expectations from rheometer studies of vulcanization behavior, the NMR technique has demonstrated that blends of NR and NBR vulcanized with sulfur/TMTM show a marked distribution of crosslinks in favor of the NR phase. The presence of even a minor proportion of NBR is sufficient to reduce the d…

Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesPolymer composites and self-healing

Influence of Polar Monomers on the Performance of Wood Fiber Reinforced Polystyrene Composites. I. Evaluation of Critical Conditions

D. Maldas、B. V. Kokta1990-09-01International Journal of Polymeric Materials

Wood fibers and nonpolar thermoplastics, e.g. polystyrene, are not the ideal partner for the preparation of composites because of a wide difference in their polarity. In the present study, polarity of the polystyrene was modified by the introduction of a—COOH group, through the reaction with maleic anhydride (MA) in t…

Natural Fiber Reinforced CompositesAdvanced Cellulose Research StudiesMaterial Properties and Processing

A Method for Quantitative Phase Analysis of Silicon Nitride by X-Ray Diffraction

D.J. Devlin、Kamal E. Amin1990-09-01Powder Diffraction

Abstract The relative intensities ratios for the determination of the relative amounts of alpha and beta phases in silicon nitride and the relative amounts of delta yttrium disilicate (Y 2 Si 2 O 7 ) and nitrogen apatite [Y 5 (SiO 4 ) 3 N] are reported. These constants were determined using an iterative method applica…

Advanced ceramic materials synthesisSemiconductor materials and devicesAdvanced Surface Polishing Techniques

Binder/Filler Interaction and the Nonlinear Behavior of Highly-Filled Elastomers

R. G. Stacer、Ch. Hübner、D. M. Husband1990-09-01Rubber Chemistry and Technology

Abstract 1. The small-deformation-viscoelastic response of elastomers containing nonreinforcing filler has been investigated. Nonlinear viscoelastic behavior was observed as a pronounced strain-amplitude dependence. The degree of this dependence was quantified using a power-law representation as a single nonlinear par…

Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesTribology and Wear Analysis

Formation of spheroidal carbide in vanadium white cast iron by rare earth modification

Wang Chao Chang、Hsu Heng Tsun、Ma Qian1990-09-01Materials Science and Technology

In this paper spheroidal VC carbide was produced by rare earth (RE) + N complex modification of white cast iron and the mechanism of modification was investigated. Primary crystallisation of VC in the melt, required for its independent growth into spheroids, was prompted by high V content of the alloy and heterogeneou…

Metal and Thin Film MechanicsAdvanced materials and compositesMetal Alloys Wear and Properties

The role of repulsive interactions in polyamide blends

Thomas Sayers Ellis1990-09-01Polymer Engineering and Science

Abstract Phase phenomena in mixtures containing any combination of aliphatic and aromatic polyamides can be formulated by the application of a mean‐field binary interaction model. This has been achieved by the quantitative analysis of the solubility of an aromatic polyamide, denoted as nylon 3Me6T, in a homologous ser…

Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesSynthesis and properties of polymers

The Mechanism of Cathodic Disbonding of Hydroxy‐Terminated Polybutadiene on Steel from Acoustic Microscopy and Surface Energy Analysis

M. Kendig、R. C. Addison、S. Jeanjaquet1990-09-01Journal of The Electrochemical Society

Scanning acoustic microscopy (SAM) has allowed observation of the microscopic details of the attack by cathodic alkaline corrosion products on a model organic coating on steel. Attack of the polymer by the alkaline corrosion products occurs at numerous localized regions resulting in mechanical degradation of the coati…

Corrosion Behavior and InhibitionUltrasonics and Acoustic Wave PropagationNon-Destructive Testing Techniques

Temperature dependence of copper(II) migration and formation of new copper(II) species during catalytic propylene oxidation on copper(II)-exchanged Y zeolite and comparison with X zeolite

Jong Sung Yu、Larry Kevan1990-09-01The Journal of Physical Chemistry

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTemperature dependence of copper(II) migration and formation of new copper(II) species during catalytic propylene oxidation on copper(II)-exchanged Y zeolite and comparison with X zeoliteJong Sung. Yu and Larry. KevanCite this: J. Phys. Chem. 1990, 94, 19, 7612–7620Publicati…

Catalytic Processes in Materials ScienceZeolite Catalysis and SynthesisCatalysis and Oxidation Reactions

The reactive extrusion of polyethylene/polypropylene blends

Wing‐Tai Cheung、D. Suwanda、S. T. Balke1990-09-01Polymer Engineering and Science

Abstract The objective of this work was to investigate the compatibilization of a blend of linear low density polyethylene with polypropylene by Injection of a free radical initiator during extrusion. The reactive extrusion process utilized a single screw extruder equipped with two static mixers. The initiator was inj…

Polymer crystallization and propertiesPolymer Nanocomposites and Propertiesbiodegradable polymer synthesis and properties

Direct Measurement of Poisson's Ratio in Elastomers

H. P. Kugler、R. G. Stacer、C. Steimle1990-09-01Rubber Chemistry and Technology

Abstract Poisson's ratio has been measured in a series of filled elastomers using a novel optoelectronic system. Relative precision of this measurement was found to be approximately 0.7% at 1% strain for this family of materials. The largest contributing error source was determined to be the tolerances that could be o…

Advanced Surface Polishing TechniquesSilicone and Siloxane ChemistryStructural Analysis of Composite Materials

Dependence of the Magnetic Superexchange on the CrċCr Distance in Dinuclear Chromium (II) Complexes

Ursula Bossek、Karl Wieghardt、Bernhard Nuber 等 4 位作者1990-09-01Angewandte Chemie International Edition in English

The spins of unpaired electrons in binuclear CrIII complexes containing the structural element A are coupled antiferromagnetically. Measurement of the temperature-dependent susceptibilities showed that the contribution of this coupling is inversely proportional to the twelfth power of the intramolecular distance betwe…

Magnetism in coordination complexesLanthanide and Transition Metal ComplexesOrganic and Molecular Conductors Research