An X-ray photoelectron spectroscopic study of electrocatalytic activity of platinum group metals for chlorine evolution

A correlation of the catalytic activity for anodic chlorine evolution of platinum group metals to the nature of the surface film formed during chlorine evolution in a sodium chloride solution was studied by X-ray photoelectron spectroscopy. The change in the surface film with increasing potential was found on platinum, including an increase in the cationic valence. This seemed responsible for the decrease in the activity for chlorine evolution on platinum in the high potential region. Increasing potential did not result in the appreciable increase in the cationic valence in the surface film on the other platinum group metals. Replacement of hydroxyl ions in the surface film by chloride ions became easier in the order of rhodium, iridium and palladium, and the activity for anodic chlorine evolution increased in this order due possibly to an increase in the amount of chloride ions in the film which seemed to be one of the reactants in the rate determining electrochemical desorption of adsorbed chlorine atom. Chlorine molecules adsorbed on the surface film were also found. It was assumed that the activity for anodic chlorine evolution might be low when the metal surface was covered by a large amount of molecular chlorine which was the reaction product.     

Adhesion aspects of levulinic-acid-modified furan polymers to crystalline zinc phosphate metal surfaces

The nature of the interfacial interactions between functional levulinic-acid-modified furan resin coatings and crystalline zinc phosphate hydrate films deposited on carbon steel surfaces has been systematically investigated. The typical surface topography of the highly crystallized zinc phosphate films was found to be characterized by the presence of a dendritic microstructure array of interlocking triclinic crystals. This structure acts significantly to develop mechanical interlocking bonds with the functional blend polymer which penetrates into the open surface structure of the films. Both the thickness of deposition film and the polar H₂O molecules of hydrate at the outermost film surface sites play essential roles in wetting by the functional liquid resin. When the polarized furan polymers spread on the oxide film surfaces, the carboxylate groups derived from the levulinic ester and acid molecules react to form strong hydrogen bonds with the crystallized H₂O molecules on the hopeite film. This formation of hydrogen bonding was shown to be a major factor affecting the chemical intermolecular attractions. A formulation consisting of 95 parts furan to 5 parts levulinic acid was found to yield the optimum protective coating. More than 5 parts levulinic acid resulted in the transformation of the characteristics of the polymer film from hydrophobic to hydrophilic.     

Relative reduction rates of fatty acid isomers by hydrazine

Mixtures of fatty acids and of hydrocarbons have been reduced by hydrazine in ethyl alcohol solution at 50 C. Samples were removed during reduction for analysis and the relative reduction rates calculated by digital computer.cis-15-Octadecenoic acid is reduced 1.3 times as fast as itscis-9-isomer. No differences were found amongcis-6,9- and -12-octadecenoic acids.cis-3-Octadecene was also reduced 1.3 times as fast as thecis-9-isomer andcis-1-octadecene 8.6 times as fast. Elaidic acid was reduced 1.27 times as fast as oleic. Presented at the AOCS Meeting, Chicago, October 1967. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Extraction of lipids from cottonseed tissue: VI. Ultrastructural morphology of isolated pigment glands

Cottonseed pigment glands, isolated from the underflow fraction of the liquid cyclone process, were examined with an electron microscope. The glands were circumscribed by a layer of tangentially flattened cells. Subjacent to the flattened cells were partially lysed cells containing recognizable remnants of cell walls. Within the lumens or matrices of the glands were myriads of pigment spherules measuring 0.1–1.5 µ in diameter. These spherules remained within the glands, even though gland walls were ruptured mechanically. Since aggregates of pigment spherules devoid of gland walls were observed in the gland-rich fraction, it was concluded that maintenance of intact pigment glands was not a requisite for successful separation of gossypol from other cottonseed components with the liquid cyclone process. Avoiding dispersion of aggregated spherules from the glandular matrix was probably just as important as maintaining intact gland walls during mechanical separation of gossypol from other cottonseed components.     

Polymer-Analog Transformations of Polycaproamide—Polyglycidyl Dimethacrylate Graft Copolymers under the Effect of Aromatic Diamine

The kinetic and thermodynamic parameters of amination of PCA—PGMA graft copolymer with p-phenylenediamine (initial reaction rate, reaction order in chemically active groups, and effective activation energy were determined. The high efficacy of p-phenylenediamine in splitting of PGMA -oxide groups, almost at the level of diamines of aliphatic structure, was demonstrated.     

Crack-wake shielding and small-scale crack-tip yielding as potential mechanisms for improving the delayed-failure resistance of silicon nitride at elevated temperatures

Requirements and microstructural design criteria for employing silicon nitride in long-term structural applications at elevated temperatures are discussed according to fracture mechanics concepts. Three least engineering parameters are considered: lifetime, flaw-tolerance and deformation under stress. “Ductile” materials are found by exploitation of small-scale crack-tip yielding which arises from the softening of their grain-boundary phase. These materials, however, are likely to exhibit poor deformation resistance. Materials with a “strong” grain boundary generally show a superior deformation behaviour but are liable to brittle fracture and static-fatigue strength degradation unless shielding mechanisms in the crack-wake be operative. The present analysis evaluates and compares these two classes of materials and the respective approaches commonly followed for their densification.     

Towards a continuous process in heterogeneous coordinated anionic ring opening polymerization

Summary The current article deals with the initial developments of the use of a continuous plug flow reactor using an original heterogeneous catalyst system for the living coordinated anionic polymerization of certain oxygenated rings. This reactor is designed in order to maintain the essential characteristics of the original batch system. One of the pertinent parameters considered here is the residence time of the reactants inside the reactor. The column has been used to investigate ethylene oxide and -caprolactone oligomerization. Initial experiments have pointed out how the molecular weights can depend on the flow rate for a fixed bed length. Some theoretical problems relative to the reactive column are discussed in order to investigate more in depth the properties of this original continuous process and to model it to find the optimal working conditions.     

Flavor and oxidative stability of hydrogenated and unhydrogenated soybean oils: Effects of antioxidants

Flavor and oxidative stabilities were studied by organoleptic evaluation and chemical analysis of three different samples of soybean oil: unhydrogented (I); hydrogenated with nickel catalyst (II); and hydrogenated with copper-chromium catalyst (III). Analyses for these oils were: I II III iodine Value 138 109 113 Linolenate, % 8.3 3.3 0.4 Each oil was deodorized with the addition of either citric acid alone or citric acid plus BHA and BHT antioxidants. Addition of antioxidants did not improve the flavor stabilities of the oils in accelerated storage tests but did improve the flavor stabilities of II and III in light exposure tests. All three oils that received the same additive treatment had equivalent flavor stability in both accelerated storage and light exposure tests. However, both hydrogenation and antioxidant treatment improved oxidative stability as measured by the Active Oxygen Method. There was good correlation between flavor score and the logarithm of the peroxide value determined at the time of tasting. Presented at the AOCS Meeting, New York, May 1977.