Cationic polyelectrolytes,XI. Polymers with quaternary N-atoms in the main chain obtained by condensation polymerization of epichlorohydrin with amines

Water soluble cationic polyelectrolytes containing quaternary nitrogen atoms within the main chain were prepared via condensation polymerization of epichlorohydrin (ECH) with dimethylamine (DMA) and N,N-dialkylaminoalkylamines. The main parameters of the reaction that influence the polymer properties are: DMA/asymmetrical diamine molar ratio, the initial concentration of amine solution, NaOH/amine molar ratio, ECH/amine molar ratio, and asymmetrical diamine structure. The feature of flexible polyelectrolyte own to the investigated polymers was emphasized by the viscosimetric behaviour in dilute aqueous solutions with and without salt presence.     

The determination of molecular weights of polymers from critical concentrations of ternary systems polymer-polymer-solvent

The dependence of the critical concentration of the ternary system polymer-polymer-solvent on the molecular weight can be expressed by the relation where c_c is the critical concentration, M? the appropriate average of the molecular weight of both polymers; A and c_c∞ are constants for the given system. The possibility of determining the molecular weight of one of the polymers from the value c_c and the molecular weight of the known polymer with the aid of equation (1) is discussed.     

On the use of pulse NMR techniques for the study of cement hydration

The application of pulse NMR to the study of hydration of cement and its constituents is discussed. The quantity of adsorbed water in hydrated samples can be most easily determined by measuring the proton free induction decay signal, whereas the rates of hardening and hydration can be best followed by measuring the proton spin-lattice and spin-spin relaxation times. The use of multiple pulse high resolution NMR in solids techniques is helpful in separating the H₂O and OH-group signals whereas ²⁷Al quadrupole coupling and spin-lattice relaxation may as well contribute to our understanding of the structure and hydration of cement.     

Calculation of separation columns by nonlinear block successive relaxation methods

A novel technique: nonlinear block successive relaxation (NBSR) method, is proposed to solve the steady-state balance equations describing separation columns. The NBSR methods are a generalization of point relaxation methods frequently used towards solution of elliptic partial differential equations. Aspects of partitioning of the original set of equations into blocks as well as ordering of blocks is discussed. Problems arising in construction of a universal program based on the NBSR methods are presented. A new procedure making use of grouping of equations according to the set of trays is proposed. Aspects of calculation of separation equipments by this procedure is discussed. It is shown that overlapping blocks may essentially improve the convergence properties of the algorithm. The procedure is very simple and can be easily used towards calculation of large separation problems on a small computer. The method described is illustrated on calculation of an absorption column. Application of the NBSR methods to solution of a complex plant is suggested.     

Calculation of local current densities and terminal voltage for a monopolar sandwich electrolyser: application to chlorate cells

Chemical engineering calculations are performed for a new type of monopolar electrolyser with power leads located on its sides, used for chlorate production. The calculation gives the value of the total cell voltage as well as of local current densities for given current load and given electrode dimensions, interelectrode gap etc. On this basis the optimization of the system is possible.List of symbols a _A constanta for the calculation of anode potential, see Equation 2a (V) - a _K constanta for the calculation of cathode potential, see Equation 2b (V) - b _A constantb for the calculation of anode potential, see Equation 2a (V) - b _K constantb for the calculation of cathode potential, see Equation 2b (V) - a _A,a _K constants in linearized Equations 3a and 3b (V) - b _A,b _K constants in linearized Equations 3a and 3b ( cm²) - d electrode distance (cm) - D _G average diameter of bubbles at pressureP ₀ (cm) - F Faraday's constant; 964 96 C - F _G,F _E effective cross-section of inter-electrode channel for the flow of gas and the electrolyte, respectively (cm²) - F _p cross-section occupied by current leads placed in inter-electrode channel for one cell (cm²) - F _T total cross-section of inter-electrode channel for one cell (cm²) - F _R cross-section for one copper rod outside the cell (cm²) - g acceleration due to gravity; 981 cm s^–2 - I _o total current (A) - I _T current flowing through one cell=I _o/n _c (A) - I _x current flowing through an electrode strip at a heightx and a distancey from the origin (A) - I _T,x current flowing through an electrode strip at a heightx andy=0 (A) - I _p,x current consumed by electrochemical reaction at a heightx betweeny=0 andy=y (A) - i _x,y local current density (A cm^–2) - _x average current density at a heightx (A cm^–2) - ¯i average current density=I _T/wL (A cm^–2) - K ₁ criterion cf. Equation 32 - K _1,x criterion cf. Equation 25 - K ₂ criterion cf. Equation 26 - K ₃ criterion cf. Equation 22 - K _3,x criterion cf. Equation 21 - K ₄ criterion cf. Equation 33 - K _4,A criterion cf. Equation 27 - K _4,K criterion cf. Equation 28 - K _4,L criterion cf. Equation 29 - K ₅ criterion cf. Equation 38 - L height of electrode (cm) - L _A,L _K length of copper rods outside the electrolyser (cm) - n _A number of equivalents per mole for anodic process yielding a gaseous phase - n _C number of cells in electrolyser - n _K number of equivalents per mole for cathodic process yielding a gaseous phase - n _r number of copper rods outside the electrolyser - P local pressure (atm) - P _o pressure on top of electrolyser (atm) - P _w pressure of water vapour in equilibrium with electrolyte (atm) - R gas constant (cm³ atm [mol° K]^–1) - (Re)_G Reynolds number for bubbles - S _A anode thickness (cm) - S _K cathode thickness (cm) - s _E specific gravity of electrolyte (g cm^–3) - s _G specific gravity of gas (g cm^–3) - s _M specific gravity of gas-electrolyte mixture (g cm^–3) - T absolute temperature (° K) - U _A,U _K ohmic voltage drops in anode and cathode, respectively (V) - U _LA,U _LK ohmic voltage drop in anode and cathode leads, respectively (V) - U _M ohmic voltage drop in the electrolyte in thez direction (V) - U _T cell voltage (V) - U _AB,U _CD ohmic voltage drop between copper rods and electrodes, see Fig. 5 (V) - _E rate of electrolyte flow in inter-electrode channel (cm s^–1) - _ET rate of electrolyte flow in inter-electrode channel at the top (cm s^–1) - _G rate of gas flow in inter-electrode channel (cm s^–1) - _GT rate of gas flow in inter-electrode channel at the top (cm s^–1) - _R velocity of bubbles corresponding to buoyance (cm s^–1) - V _E volume flow rate of electrolyte in inter-electrode channel (for one cell) (cm³ s^–1) - V _G volume rate of gas flow in inter-electrode channel (for one cell) (cm³ s^–1) - V _GT volume rate of gas flow in inter-electrode channel at the top (cm³ s^–1) - w width of the active surface of an electrode (cm) - w _A width of the inactive part of an anode (cm) - w _K width of the inactive part of cathode (cm) - w _AE width of the inactive part of an anode embedded in electrolyte (cm) - w _KE width of the inactive part of a cathode embedded in electrolyte (cm) - x, y, z length in the direction of co-ordinates - , _T volume fraction of bubbles at a heightx and at the top - _A, _K anodic and cathodic potentials - _A anodic current efficiency for gas evolution - _K cathodic current efficiency for gas evolution - v kinematic viscosity of electrolyte (cm² s^–1) - _A specific resistance of an anode ( cm) 5.76×10^–5 - _K specific resistance of a cathode ( cm) 1.21×10^–5 - _E specific resistance of electrolyte ( cm) - _M specific resistance of a gas-electrolyte mixture between electrodes ( cm) - _A ratio of active anode surface to the productwL - _K ratio of active cathode surface to the productwL     

Theory of porous electrodes—XII. The negative plate of the lead-acid battery

Partial differential equations describing the transport of mass and electricity in the pores of the negative electrode of a lead-acid battery were derived. The theory is based on exact transport equations and on the assumption that the electrode potential is governed by the Nernst equation. Volume changes in both phases are taken into account. Numerical solutions depend on the product of electrode thickness times current density and on the initial porosity. Differences between the negative and positive plates are discussed.     

Theory of porous electrodes—XI. The positive plate of the lead-acid battery

Partial differential equations describing the transport of mass and electricity in the pores of the positive electrode of a lead acid battery were derived. The theory is based on exact transport equations and on the assumption that the solid porous matrix has a metallic conductivity. Volume changes in both phases are taken into account. Numerical solutions obtained on a computer are presented for the case where the influence of electrolyte between the electrodes can be neglected. The solutions depend on the product of electrode thickness times current density, and on the initial porosity.     

Production of high strength Al-Zn-Mg-Cu alloys by spray forming process

1　ＩＮＴＲＯＤＵＣＴＩＯＮＡｌ Ｚｎ ( 7×××ｓｅｒｉｅｓ)ａｌｌｏｙｓｈａｖｅｂｅｅｎｗｉｄｅｌｙｕｓｅｄｂｅｃａｕｓｅｏｆｈｉｇｈｓｔｒｅｎｇｔｈ ,ｃｏｒｒｏｓｉｏｎ ｒｅｓｉｓｔａｎｃｅａｎｄｏｔｈｅｒｇｏｏｄｐｒｏｐｅｒｔｉｅｓ[1 ,2 ] .Ｂｕｔａｐｒａｃｔｉｃａｌｃｏｎｔｅｎｔｌｉｍｉｔｏｆ7%Ｚｎ (ａｌｌｏｙｓ 70 75,71 75ａｎｄ 7475ｅｔｃ)ｉｓｉｍｐｏｓｅｄｆｏｒｃｏｎｖｅｎｔｉｏｎａｌｃａｓｔｍａｔｅｒｉａｌｓｂｅｃａｕｓｅｏｆｓｏ ｌｕｔｅｍａｃｒｏ ｓｅｇｒｅｇａｔｉｏｎａｎｄｃｏａｒ…     

Li_(1 2x)Zn_(1-x_PO_4的合成及其锂离子的导电性

以Li2 CO3,ZnO和NH4 H2 PO4 为原料 ,采用传统固相合成法和柠檬酸盐溶胶凝胶法制备了组成为Li1 2xZn1-xPO4 (x =0～ 0 .5 )的固体粉末和烧结体。对合成材料作了DTA ,TG ,XRD和SEM等分析 ,并用交流阻抗技术测定了样品的导电性。实验结果表明 ,与传统的固相合成方法相比 ,溶胶凝胶法可以使样品合成温度降低约 40 0℃ ,并且具有较高的导电率。     

关于低压及差压铸造发展方向的探讨

探讨了低压、差压铸造主机、液面加压控制系统、保温炉和升液管的改进与发展趋势