Stress relaxation in carbon black loaded butyl rubber

The dependence of equilibrium force (F^*) on the strain ratio (α) of carbon black loaded butyl rubber was studied. The relation between elastic constant and volume fraction of carbon black was found in good agreement with that obtained by Guth and Gold relation at low concentrations using the shape factor (f = 6.5). The relaxation time and viscosity (η) were calculated by using stress relaxation of these samples at different compression strains. The same agreement was observed in the relation between viscosity and volume fraction of carbon black concentration. The results are discussed according to the dispersion mechanism of carbon black in rubber. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1067–1076, 2000     

Influence of hydrostatic pressure on the electrical properties of unvulcanized FEF-loaded SBR

Styrene butadience rubber (SBR-1502) loaded with different concentrations of FEF carbon black was tested to find out the effect of pressure on its electrical properties during vulcanization. Using the thermodynamically calculated values of the pressure coefficient (K), the thermoelastic coefficient (L = ?T/?P) was also estimated and compared with that obtained by other workers. The thermoelastic coefficient was found to be strongly dependent on the carbon black concentration.     

Condensation of 4-phenyl-3,5-dicarboethoxycyclopentane-1,2-dione with primary amines

Condensation of the title compound ( 1 ) with primary aromatic amines gave the dianilides ( 2 ), which cyclized to cyclopenta[1,2-c:4,3-c′]diquinolines ( 3 ). Treatment of 1 with o-phenylenediamine or 2,3-diaminopyridine afforded cyclopenta[2,1-b:3,4- b ′]bis[1,5]benzodiazepine ( 4 ) and bis[1,5]pyrido[b]diazepine derivative ( 5 ), respectively. Whereas, with o-aminophenol a mixture of 2c and cyclopenta[2,1- b :3,4- b ′]bis[1,5]benzoxazepine ( 7 ) was obtained. Pechmann reaction of 1 with m-cresol gave the bis[1]benzopyrane ( 9 ). Mannich reaction of 1 with benzylamine afforded the 3-azabicyclo[3.2.1]octane system ( 10 ).     

Removal of heavy‐metal ions by magnetic beads containing triazole chelating groups

The aim of this study was to prepare magnetic beads that could be used for the removal of heavy‐metal ions from synthetic solutions. Magnetic poly(ethylene glycol dimethacrylate–1‐vinyl‐1,2,4‐triazole) [m‐poly(EGDMA–VTAZ)] beads were produced by suspension polymerization in the presence of a magnetite Fe₃O₄ nanopowder. The specific surface area of the m‐poly(EGDMA–VTAZ) beads was 74.8 m²/g with a diameter range of 150–200 μm, and the swelling ratio was 84%. The average Fe₃O₄ content of the resulting m‐poly(EGDMA–VTAZ) beads was 14.8%. The maximum binding capacities of the m‐poly(EGDMA–VTAZ) beads from aquous solution were 284.3 mg/g for Hg²⁺, 193.8 mg/g for Pb²⁺, 151.5 mg/g for Cu²⁺, 128.1 mg/g for Cd²⁺, and 99.4 mg/g for Zn²⁺. The affinity order on a mass basis was Hg²⁺ > Pb²⁺ > Cu²⁺ > Cd²⁺> Zn²⁺. The binding capacities from synthetic waste water were 178.1 mg/g for Hg²⁺, 132.4 mg/g for Pb²⁺, 83.5 mg/g for Cu²⁺, 54.1 mg/g for Cd²⁺, and 32.4 mg/g for Zn²⁺. The magnetic beads could be regenerated (up to ca. 97%) by a treatment with 0.1M HNO₃. These features make m‐poly(EGDMA–VTAZ) beads potential supports for heavy‐metal removal under a magnetic field. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Material Parameters for Creep Rupture of Austenitic Stainless Steel Foils

Creep rupture properties of austenitic stainless steel foil, 347SS, used in compact recuperators have been evaluated at 700 °C in the stress range of 54-221 MPa to establish the baseline behavior for its extended use. Creep curves of the foil show that the primary creep stage is brief and creep life is dominated by tertiary creep deformation with rupture lives in the range of 10-2000 h. Results are compared with properties of bulk specimens tested at 98 and 162 MPa. Thin foil 347SS specimens were found to have higher creep rates and higher rupture ductility than their bulk specimen counterparts. Power law relationship was obtained between the minimum creep rate and the applied stress with stress exponent value, n = 5.7. The value of the stress exponent is indicative of the rate-controlling deformation mechanism associated with dislocation creep. Nucleation of voids mainly occurred at second-phase particles (chromium-rich M₂₃C₆ carbides) that are present in the metal matrix by decohesion of the particle-matrix interface. The improvement in strength is attributed to the precipitation of fine niobium carbides in the matrix that act as obstacles to the movement of dislocations.     

大塑性变形技术制备块状超细晶TiNi基形状记忆合金研究进展

详细介绍了块状超细晶TiNi基形状记忆合金的研究进展,包括其制备工艺与显微组织、马氏体相变行为、力学性能和形状记忆特性以及超弹性性能,并介绍了其在医学和工程领域的实际应用,最后探讨了块状超细晶TiNi基形状记忆合金今后的研究发展方向。     

Effect of Boronizing on Operating Stability of Steel AISI 304L under Erosion Impact of Hard Particles

Metal Science and Heat Treatment - The effect of solid boronizing at 950°C for 2 and 4 h on the phase composition, microstructure, hardness and abrasive wear of steel AISI 304L is studied...     

Selective separation of cobalt and nickel by supported liquid membranes

The selective separation of cobalt from acidic media, containing both equimolar and nonequimolar mixtures of cobalt and nickel, was examined by supported liquid membranes using Alamine 336 as mobile carrier dissolved in various diluents. The membrane support was microporous hydrophobic polypropylene Celgard 2500 (25 μm thick, 0.209 × 0.054 μm pore size and 55% porosity). Acetic acid-Na acetate buffer was used for the adjustment of the feed pH which was critical. Various parameters were experimentally studied and the optimum conditions were determined.     

Removing of resins from crude oils

Crude oil contains four chemical group classes, namely saturates, aromatics, resins, and asphaltenes (SARA fractions). Resins fraction of crude oil comprises polar molecules often containing heteroatoms such as nitrogen, oxygen, or sulfur. Resin is a heavier fraction than aromatics and saturates. Resins are composed of fused aromatic rings with branched paraffin and polar compounds. The resin fraction is soluble in light alkanes such as pentane and heptane, but insoluble in liquid propane. The resins are adsorbed on a solid such as alumina, clay, or silica, and subsequently recovered by use of a more polar solvent and the oils (aromatics and saturates) remain in solution. The resins often coprecipitate with the asphaltenes in controlled propane deasphalting procedures. The composition of the resins can vary considerably and is dependent on the kind of precipitating liquid and on the temperature of the liquid system. The resins are adsorbed on a solid such as alumina, clay, or silica, and subsequently recovered by use of a more polar solvent and the oils (aromatics and saturates) remain in solution.     

An Engineering Approach to the Treatment of Constant Pressure Boundary Condition in Block-Centered Grid in Reservoir Simulation

Abstract

Block-centered grid and point-distributed grid are the most widely used grids to describe a petroleum reservoir as units in reservoir simulation. In the point-distributed grid, the boundary grid point falls on the boundary, whereas the point that represents the boundary grid block is half a block away from the boundary. As a result, the point-distributed grid gives accurate representation of constant pressure boundary condition. In the block-centered grid, the approximation of a constant pressure boundary is implemented by assuming the boundary pressure being displaced half a block coincides with the point that represents the boundary grid block and by assigning boundary pressure to boundary grid block pressure. This is a first-order approximation. A second-order approximation was suggested, but it has not been used because it requires the addition of an extra equation for each reservoir boundary of a boundary grid block. Furthermore, the extra equations do not have the form of a flow equation.

This article presents an engineering approach for the representation of a constant pressure boundary condition in a block-centered grid. The new approach involves adding a fictitious well term per boundary to the flow equation of a boundary grid block. This treatment is valid in both rectangular and radial-cylindrical grids. The flow toward a fictitious well is linear in rectangular coordinates and radial in radial-cylindrical coordinates. The flow rate equations for fictitious wells were derived from the inter-block flow rate term between a boundary grid block and the grid block that falls immediately outside reservoir boundary. These flow rate equations are presented and tested. With the new treatment, both block-centered grid and point-distributed grid produce pressure profiles with comparable accuracy. In other words, the use of the point-distributed grid does not offer any advantage over the block-centered grid in rectangular and radial-cylindrical coordinates for the case of constant pressure boundaries.