Physical and electrochemical properties of quaternary ammonium bis(oxalato)borates and their application to electric double-layer capacitors

The use of nonhalogenated electrolyte salts for electrochemical devices is very important from the point of view of safety and cost. We have investigated the physical and electrochemical properties of a series of quaternary ammonium bis(oxalato)borates (QABOBs) and the performance of electric double-layer capacitors (EDLCs). The mass and van der Waals volume of BOB⁻ are higher and larger than those of BF₄⁻. The mass densities, viscosities, and surface tensions of propylene carbonate (PC) solutions containing the QABOBs are higher than those obtained for tetraethylammonium tetrafluoroborate (TEABF₄), and the electric conductivities become lower. However, the electrochemical voltage windows measured with an activated carbon electrode and the gravimetric capacitances of 2025-type coin cells are comparable to those obtained for the PC solutions containing the TEABF₄.     

Intraparticle ion exchange mass transfer accompanied by instantaneous irreversible reaction

A model is proposed for intraparticle mass transfer of ion exchange coupled with instantaneous irreversible reaction. The theoretical equations are der     

Mechanical behaviour of brittle materials under hydrostatic pressure (on torsion of chalk cylinders)

Torsion tests were carried out on black-board chalk under hydrostatic pressures of up to 4·0 kgf/mm² in order to investigate the pressure effect on the deformation and fracture of brittle materials. Chalk, which is very weak (the tensile strength is about 0·1 kgf/mm²), was chosen as test material because the ratio of the applied hydrostatic pressure to the tensile strength of the material could be easily raised to high values.It is shown that there is a distinct difference in the characteristics of deformation and fracture between specimens under a pressure which is higher than a critical value of 0·3 kgf/mm² and those under a pressure less than that value. It is also shown that under relatively high pressure a macroscopic crack is formed around the twist angle yielding the maximum torque and thereafter it propagates helically with increase of twist angle.     

Tunneling of quasiparticles between two weakly coupled systems of superfluid helium

Quasiparticle tunneling in a weakly coupled system of liquid helium is theoretically studied, in analogy with normal electron tunneling of superconductor junctions. Chemical potential difference in this case is to be created across the junction by a superfluid flow parallel to the junction. Calculation shows that a collimated beam of quasiparticles would show several divergences of tunneling current at specific angles of incidence or at specific values of superfluid velocity, while no divergence is expected for the integrated current, which is an important difference from the case of superconductor junctions.     

Adsorption and desorption of complex metal ions in polyviologen or its polyion complexes with poly(sulphonate)s by the control of a given potential

Complex anions and a complex cation were concentrated electrostatically in the domain of polyviologen by the control of a given potential. Pyrolytic graphite electrodes were coated with polyviologen or the polyion complex of polyviologen with poly (sulphonic acid) for the concentration of complex anions or the complex cation, respectively. In an aqueous solution in which Mo(CN)^4?₈ and Fe(CN)^4?₆ coexisted, the polyviologen-coated electrode predominantly concentrated Mo(CN)^4?₈. Furthermore, the Mo(CN)^4?₈ incorporated in the film was desorbed by reducing the charge density of polyviologen. The desorption rate was proportional to the charge density of polyviologen which depended on a given potential. On the other hand. Ru(NH₃)³⁺₆ was adsorbed in the domain of the polyion complex of polyviologen with poly (sulphonic acid) and it was desorbed completely in a few seconds by reducing the overall charge density of the polyion complex. Generally, reversible adsorption-desorption of multivalentions could be performed by changing the given potential if redox-active sites were fixed or chemically bonded in the polymer matrix. Redox-active polymers were stabilized by polyion complex formation with oppositely charged polyelectrolytes.     

Melt rheology of high-density polyethylene

The melt rheology of high density polyethylene was investigated. Linear viscoelasticity, capillary flow properties, and molecular weight parameter were measured with a plate relaxometer, capillary rheometer, and gel permeation chromatography, respectively. Intimate correlations among the slope of relaxation modulus curve, non-Newtonian flow behavior, Barus effect, and molecular weight parameter, M_z(M_z+1)/M_w, respectively, were found.