Effects Of Chemical Interactions Research Articles

Effect of chemical interaction between surface oxidized carbon black and carboxylated nitrile rubber on dynamic properties

AbstractMonsanto rheometric, dynamic mechanical, and solvent swelling studies indicate that functional groups of oxidized carbon black chemically react with carboxylated nitrile rubber (XNBR) when heated at high temperature for prolonged time. The reinforcing ability of the surface oxidized carbon black, measured by failure and hysteresis properties, is higher than the nonoxidized counterpart. © 1995 John Wiley & Sons, Inc.

Model filled polymers. XV: The effects of chemical interactions and matrix molecular weight on rheology

AbstractIn order to explore the effects of chemical composition on the rheological behavior o filled polymeric systems, we prepared polystyrene (9PS) and poly(methyl methacrylate) (PMMA) particles crosslinked with either ethylene glycol dimethacrylate (EGDMA) or divinyl benzene (DVB), and mixed these particles in a PMMA matrix. PS particles crosslinked with 10% EGDMA are better dispersed in a PMMA matrix, compared to PS particles, crosslinked with 10% DVB, due to the compatibilizing effect of EGDMA. For PMMA particles crosslinked with DVB, particle‐matrix interactions in a PMMA matrix are smaller than in EGDMA‐PMMA filled PMMA. Therefore, particles tend to agglomerate in PMMA composites filled with DVB‐PMMA particles, especially in a low molecular weight matrix. We compared PMMA matrices of molecular weights 35,000 and 75,000. Higher particle‐matrix interaction in the higher molecular weight matrix resulted in lower relative viscosities for DVB‐PS filled systems, due to better dispersion of the particles. Composites filled with EGDMA‐PS particles behave similarly to those filled with DVB‐PS particles. PMMA composites filled with DVB‐PMMA particles have a lower relative viscosity in the higher molecular weight PMMA matrix at low shear rates, due to better dispersion in the higher molecular weight matrix. However at high shear rates, particles are well dispersed in both PMMA matrices and, then, the relative viscosity is higher due to better bonding in the higher molecular weight matrix.

Effects of oxygen on soot formation in methane, propane, and n-Butane diffusion flames

Overventilated coflow axisymmetric laminar diffusion flames of methane, propane, and n-butane were used to study the influence of oxygen addition to the fuel side on soot formation. The line-of-sight soot volume fractions and the visible flame profiles were measured as a function of axial location along the centerlines of pure fuel flames, and the flames in which the fuel was diluted either with oxygen or nitrogen at selected temperatures of the reactants, to maintain a constant adiabatic flame temperature. The relative influences of dilution and direct chemical interaction effects of oxygen in the fuel gas mixture were quantified. It was found that, when allowance was made for the influence of dilution and thermal effects, the addition of oxygen to the methane diffusion flame chemically suppressed soot formation. This suppression was argued to be due to the reduction in acetylene concentration in the pyrolysis products as the oxygen mole fraction in methane was increased. The chemical influence of oxygen addition to methane decreased when the adiabatic flame temperature was decreased by decreasing the temperature of the reactants. In propane and n-butane flames, on the other hand, oxygen addition chemically enhanced soot formation. The degree of enhancement was small for low mole fractions of oxygen, but increased with increasing oxygen. When oxygen is added to the fuel side of a diffusion flame, two counteracting chemical effects are expected: Oxygen promotes fuel pyrolysis and hence production of hydrocarbon radicals and H atoms which enhance soot formation. On the other hand, aromatic radicals and critical aliphatic hydrocarbon radicals are removed by reactions with molecular oxygen and oxygen atom. The net chemical influence is the difference of these two counteracting effects.

The Function of Buffer Layers and Defects in Heteroepitaxial BaxSr1-xTiO3/YBa2Cu3O7-x/CeO2/Y-ZrO2/Si/Al2O3 Multilayers

AbstractDifferent aspects of interfacial interactions during the growth of epitaxial oxides are illustrated in a BaxSr1-xTiO3/YBa2Cu3O7-x/CeO2/Y-ZrO2/Si/Al2O3 heteroepitaxial multilayer. The effect of chemical interaction, interdiffusion, epitaxial strain and thermal strain are exemplified. It is shown how buffer layers can be used to compensate for otherwise detrimental interactions. Considerations necessary for annealing following the film depositions are also addressed. Even if the described structures are specific for this system, similar considerations need to be made for other oxide systems as well. The present description can provide help to identify suitable material combinations.

Chemical Interactions in Sulfide Mineral Tailings∗

This paper reviews some of the work that has attempted to identify species which exist, or are formed, in sulfide mineral tailings, indicating that the resultant chemical reactions, combined with physical properties of the tailings and their surrounds, can explain movement and attenuation of metal concentrations. Additionally, it introduces the consideration of the reactions and speciation which occur in the reduction zone of a sulfide tailings heap, which is a subject that has previously received little attention. As evidence for reductive dissolution of sulfides in tailings, an investigation of the Anaconda Tailings (in Montana, U.S.A.) is cited. The contention that chemical modeling provides an accurate basis for predicting tailings chemistry is refuted. Attempts to model the effects of chemical interactions in sulfide tailings have to date been distinctly inaccurate. The use of various computer codes to aid modeling of the chemical reactions in these tailings has become widely adopted, but the success...

Effect of chemical interaction on barenblatt crack profiles in brittle solids

A self-consistent solution for continuum-slit Barenblatt cracks with interactive chemistry is presented. Environmental species entering the crack mouth are limited in their transport along the ever-narrowing interface by molecular size restrictions. The ensuing cohesion zone behind the tip consists of three regions: an extended far region of weak solid-fluid-solid attraction; a small intermediate region of strong solid-fluid-solid repulsion; and an exclusionary near-tip intrinsic region of strong solid-solid attraction. To facilitate an analytical solution of the equations for the crack-opening displacements, the cohesion stresses are taken to be uniformly distributed within each of these zones. The magnitudes of these stresses are expressed in terms of the intersurface energies that define equilibrium crack states, for virgin and healed interfaces. Illustrative calculations of the crack profiles are given for the well-documented mica-water system. It is shown that the penetrating species cause a significant local bulge in the repulsion region, consistent with Thomson's picture of a molecular wedge.

Interaction of reactive ions with Pt(100). I. Neutralization and surface trapping

Scattering of (10–400 eV) O+, O+2 , C+, CO+, and CO+2 ions from a Pt(100) surface has been studied. Below 100 eV, the peak position of the angular distribution for survival ions was shifted parallel to the surface, and the lobe width was very narrow in comparison with noble-gas ions. This suggests that surface trapping due to chemical interaction takes place at very low energies. The importance of collisional neutralization at high energies is demonstrated by the result that the yields of reactive ions decrease steeply with increasing incident energy. The scattering ion yields of O+ and O+2 ions, especially, were very low, being less than 1/100 and 1/10 of those of nitrogen ions, respectively. These results show that a chemical interaction effect is significant for the scattering of oxygen ions.

An in situ Mössbauer study on the metal-support interaction of supported iron catalysts for CO hydrogenation

Iron supported catalysts were investigated by in situ Mossbauer spectroscopy. Results showed that MSI can be vell Interpreted as a combination of the dispersion effect and the chemical interaction effect.

Thermoanalitical studies of chemical reactions between mercury telluride and some metals

Abstract Chemical Interaction between mercury telluride and metals such as Sn, Pb, In, Ga, Cu and Ag has been studied with the use of thermoanalytical studies and microstructural analysys. It has been found that HgTe starts interacting with Sn, Pb, In and Ga immediately after the melting of metal, though the formation of an intermediate layer of tin, lead and gallium tellurides considerably inhibits the progress of the chemical reaction. as the temperature increases, there occurs destruction of the layer formed and an intense chemical interaction which corresponds to exothermic peaks on the heating, curves. In the interaction between HgTe and In, the formation of an intermediate layer does not take place, which causes a graduel chemical interaction with the formation of InTe and precipitation of free Mercury. Exothermic effects of chemical interaction between Cu, Ag and HgTe appear on the heating thermograms immediately after the melting of HgTe.

The electrical resistivity of liquid Li-Sn, Na-Sn and Na-Pb alloys: strong effects of chemical interactions

Electrical resistivities of liquid Li-Sn, Na-Sn and Na-Pb alloys have been measured. The resistivities exhibit distinct maxima close to 'stoichiometric' compositions: Li4Sn, Na4Sn, Na4Sn3 and Na4Pb. At the same compositions the temperature derivative d rho /dT is negative and -d rho /dT assumes extraordinarily large values. The effects are attributed to strong chemical interactions between the components. These interactions tend to reduce the density of states at the Fermi level.

Influence du carbone sur la diffusion du chrome et du nickel en volume et dans les joints de grains de l'alliage Ni-Cr 80/20

Measurements on the diffusion coefficients of 63Ni and 51Cr in 80/20 Ni-Cr alloys of varying carbon content show that the carbon level has no effect on volume diffusion; on the other hand the influence of this element on the coefficients of intergranular diffusion are evident irrespective of whether the carbon is present as carbide precipitates at the grain boundaries or completely dissolved. Thus when T > 1050°C, i.e. in the absence of carbide precipitates, D j · δ 51Cr = 1.3 × 10−7 exp[(−150 kJ/RT)] cm 3 s −1 and D j · δ 63 Ni = 3 × 10 −6 exp[(−209 kJ/ RT)] cm 3 s −1; when T < 1050°C the presence of carbide precipitates causes a simultaneous increase in D o J and Q, while when carbon is present solely in solution a decrease in the frequency factor is met only for the diffusion of chrome; in this last case segregation of neither carbon, nor chrome nor nickel has been observed at the grain boundaries. It has been necessary to consider the effect of chemical interactions between the chrome and carbon atoms in pipe positions in the grain boundaries to explain the change in the frequency factor D o J.

Chemical effects of thermonuclear plasma interactions with insulator and metal surfaces

The interactions of chemically reactive ions with insulator and metal surfaces result in specific chemical effects which must be considered in sputtering, blistering, trapping and re-emission processes involving these projectiles. Chemical sputtering and chemical trapping of ion beam flux are examples of chemical interaction effects which are discussed. Bombardment of a niobium surface by oxygen and nitrogen ions results in the formation of sputtered niobium oxide and nitride molecules. The molecular species are identified and characterized by means of their vibrational spectra using isotopic substitution and matrix isolation techniques. Results using matrix isolation spectroscopy for both physical and chemical sputtering studies on materials of CTR interest are presented. Chemical trapping is evaluated as a method of chemically pumping the major fraction of ion beam flux in the divertor of next generation tokamaks.

An example of the effect of chemical interactions on transport phenomena

AIChE JournalVolume 20, Issue 4 p. 819-820 R & D Note An example of the effect of chemical interactions on transport phenomena B. W. Brodman, B. W. Brodman Munitions Development and Engineering Directorate, Frankford Arsenal, Philadelphia, Pennsylvania 19137Search for more papers by this authorM. P. Devine, M. P. Devine Munitions Development and Engineering Directorate, Frankford Arsenal, Philadelphia, Pennsylvania 19137Search for more papers by this authorM. T. Gurbarg, M. T. Gurbarg Munitions Development and Engineering Directorate, Frankford Arsenal, Philadelphia, Pennsylvania 19137Search for more papers by this author B. W. Brodman, B. W. Brodman Munitions Development and Engineering Directorate, Frankford Arsenal, Philadelphia, Pennsylvania 19137Search for more papers by this authorM. P. Devine, M. P. Devine Munitions Development and Engineering Directorate, Frankford Arsenal, Philadelphia, Pennsylvania 19137Search for more papers by this authorM. T. Gurbarg, M. T. Gurbarg Munitions Development and Engineering Directorate, Frankford Arsenal, Philadelphia, Pennsylvania 19137Search for more papers by this author First published: July 1974 https://doi.org/10.1002/aic.690200426Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume20, Issue4July 1974Pages 819-820 RelatedInformation