The hydrogen-electrode reaction in the isotopically mixed system—II. Evaluation of the electrolytic separation factor of deuterium from the rest potential of the hydrogen electrode in the deuterium-containing system

The rest potential, E_r, of the hydrogen electrode in deuterium-containing hydrogen and a solution of light water as referred to the reversible hydrogen electrode in the light hydrogen and the same solution is formulated as a function of deuterium content of the gaseous hydrogen and the deuterium separation factor, S_b, in the hydrogen ionization reaction. It is shown that the relation is not significantly affected by the operative mechanism of the hydrogen-electrode reaction. Consequently, the relation provides a convenient method of evaluating S_b from the observation of E_r.

Experiments were carried out on Pt, Ni, Au and Ag in the system composed of deuterium-containing hydrogen and light water. The value of S_b as evaluated from E_r was practically independent of the deuterium content in the gaseous hydrogen. The values obtained were 1·1 for Pt in acidic and alkaline solutions, 1·6 for Ni in alkaline solution, 1·2 for Au and 1·5 for Ag, both in acidic solution. These values multiplied by the partition coefficient of deuterium between hydrogen and water (4·0 at room temperature) give approximate values of the deuterium separation factor in the hydrogen evolution reaction.     

Measurement of the melting points of oligomers obtained in the manufacture of poly(ethylene terephthalate)

The melting points (T_m) were measured for oligomers obtained by a direct continuous esterification process between terephthalic acid and ethylene glycol. Multiple regression analyses of data were carried out, and an equation was obtained for predicting melting points with correlation coefficient of ～0.99.     

Facile preparation of amphiphilic oxyethylene-oxypropylene block copolymers by selective triazine coupling

A novel synthetic route for preparing high molecular weight poly(oxyalkylene) block copolymers has been developed by using 2,4,6-trichloro-1,3,5-triazine (cyanuric chloride, cc) as the coupling core. The coupling reaction involves the selective substitutions of oligo(oxyalkylene)-amines onto three chlorides of the triazine ring in a stepwise manner at 0, 25 and 130 °C. By judiciously selecting the starting amines and reaction conditions, one can tailor the copolymer structures with different block configurations (tri-block, multi-block, random and alternating block). The prepared copolymers can have a high molecular weight, up to 25,600 g/mol (GPC polydispersity=1.48), and also high thermal stability due to the presence of triazine functionalities. The copolymers with hydrophilic and hydrophobic oligo(oxyalkylene) blocks are of versatile properties in solubility (water soluble or water insoluble) and morphology (crystalline or amorphous). With a specific structure of alternating oligo(oxyethylene)/oligo(oxypropylene) blocks (2000 g/mol each block), the copolymer exhibits the property of self-association. It reduces the interfacial tension of toluene/water as low as 0.5 dyne/cm at the critical micelle concentration of 0.01 wt%.     

Electrochemical removal of both NO and CH4 under lean-burn conditions

An electrochemical cell, Pd|YSZ|Pd, was constructed in order to remove both NO and CH₄ in the presence of excess oxygen. When direct current was supplied to the cell with a flow of a mixture of NO, CH₄, O₂, H₂O and CO₂ at 700° C, NO was reduced to nitrogen at the cathode, and CH₄ was oxidized to CO _x at both the anode and cathode. At the cathode, the reduction of NO and the oxidation of CH₄ proceeded with the removal of chemisorbed oxygen species from the Pd surface, and at the anode, the oxidation of CH₄ was enhanced by forming an active oxygen atom.     

Antioxidant for fats and oils from canary seed: Sterol and triterpene alcohol esters of caffeic acid

Several kinds of seeds used as bird feed were extracted successively with hexane, ether and methanol. In the antioxidant test with extracts, the ether extract from canary seeds showed the highest activity. The antioxidant fraction separated from it by thin layer chromatography showed excellent activity for lard and sardine oil. The effective components were identified by gas chromatography and gas chromatography-mass spectrometry of the hydrolyzed products as the esters of caffeic acid with cycloartenol, gramisterol, sitosterol and campesterol with the minor amounts of 24-methylenecycloartanol, obtusifoliol, brassicasterol and Δ7-stigmastenol.     

Rebound test to measure the strength of polymeric materials

In this work it is shown that rebound experiments, carried out at low blow impact and by means of instrumented pendula, can be described in terms of the equation for a freely oscillating linear viscoelastic body with added mass. The experimental and calculated load-time curves are in very good agreement when the behavior of the material is linear viscoelastic; the assumptions made (transitory time shorter than rebound time, and negligible mechanical friction) are thus proved to be reasonable. The rebound test, which can be carried out on unnotched or notched specimens, allows one to obtain quickly and easily relevant material properties such as Young modulus or compliance, stored and dissipated energies, and the upper linear elastic limit at a testing speed not too far from that of impact testing.     

Excess Gibbs free energy and excess enthalpy for mixtures of benzene and 1,1,2-trichlorotrifluoroethane

The rapid measurement of static vapour pressures of binary liquid mixtures as a function of composition by a new continuous-dilution apparatus is described. These measurements, together with the computed excess Gibbs free energies, are reported for mixtures of benzene and 1,1,2-trichlorotrifluoroethane at 283.30, 287.83, 293.21, 298.21, 303.06 and 308.15 K over the full composition range, and are compared with the results of Linford and Hildebrand. The excess enthalpies were measured directly at 303.15 K using a batch calorimeter. The equimolar excess enthalpy is + 754 J mol^?1, which is close to the value, + 727 J mol^?1, calculated from the temperature dependence of the computed equimolar excess Gibbs free energies.     

Precipitation from glassy polymer solutions

Solid solutions of general-purpose polystyrene containing crystalline tetrabromoxylene, tetrachloroxylene, or tetrachlorobenzene were prepared. The effects of the low molecular weight crystalline additive concentration and the thermal history on the thermal properties of the system have been studied. The system solubility, rejection of solute, etc., were characterized by such techniques as rheology, thermal analysis (DSC), and Vicat softening point.     

Comparison between some empirical equations of state for polymers

Some commonly used empirical equations of state for polymers are considered: the Spencer-Gilmore equation with two and three adjustable parameters, the Whitaker-Griskey equation, and the Rehage-Breuer equation. Also, a new equation is proposed: the Inverse Volume equation. These equations are evaluated with regard to fitting experimental P-V-T data and agreement with experimental data on isothermal compressibility and thermal expansion coefficient. The adjustable parameters for each equation are determined with the help of Rosenbrock's optimum-seeking technique. Analysis of the residuals on specific volume for a variety of materials suggests that the Spencer-Gilmore equation with three adjustable parameters, the Rehage-Breuer and the Inverse Volume equations yield the smallest and most random residuals and thus the least systematic error. The same three equations mentioned above yield results in good agreement with experimental isothermal compressibility data. However, among all the equations considered in this study, the Inverse Volume equation yields the best agreement with experimental thermal expansion coefficient data. Furthermore, it is the only equation to correctly predict the rise in thermal expansion coefficient with increasing temperature.