New Poly(Methacrylate)s Containing Benzylpiperazine and Methylpiperidine Moieties

The synthess of two new methacrylate esters containing 2-(4-benzyl piperazin-1-yl)-2-oksoethyl and 2-(4-methylpiperidin-1-yl)-2-oksoethyl group are described. The monomers produced from the reaction of corresponding 4-methylpiperidinechloroacetamide and 1-benzylpiperazinechloroacetamide with sodium methacrylate were polymerized in DMSO solution at 65°C using AIBN as an initiator. The monomers and their polymers were characterized by IR, ¹H- and ¹³C-NMR spectroscopy. The glass transition temperature of the polymers were investigated by DSC and the apparent thermal decomposition activation energies (E _d ) were calculated by Ozawa method using the SETARAM Labsys TGA thermobalance. By using gel permeation chromatography, weight average ( ) and number average ( ) molecular weights and polidispersity, indices of the polymers were determined.     

Synthesis and electrical properties of poly[2-(2-(4-trifluoromethyl)phenyl)ethenyl-1,4-phenylenevinylene] and PPV copolymers

Summary Poly[2-(2-(4-(trifluoromethyl)phenyl)ethenyl)-5-methoxy-1,4-phenylenevinylene] (PFEMPV) and a series of PPV copolymers containing 1,4-phenylenevinylene (PV) units were synthesized through a water-soluble precursor route, and their electrical and third-order nonlinear optical properties were studied. The PFEMPV films could not be doped with I₂, but FeCl₃-doped films showed an electrical conductivity of 5.0x10^-4 S/cm. The conductivities of FeCl₃-doped copolymer films ranged from 2.0x10^-3 to 2.0 S/cm depending on their copolymer compositions. The third-order nonlinear optical susceptibility, ⁽³⁾(–;,,–), was also investigated by the degenerate four wave mixing technique at 602 nm. The ⁽³⁾ value of PFEMPV was 6.9x10^-11 esu. The photoluminescence spectrum of PFEMPV shows its emission maximum at 550 nm.     

Hydrogen half-cells in molten salts. A potentiometric investigation of the systems (Pt or Au) H2O/H2, OH− in fused alkali nitrates

The potentiometric behaviour of the hydrogen electrodes (Pt or Au) H₂O-H₂, OH_–has been investigated in molten (Na_0·5, K_0·5)NO₃ at 503 K. In both cases the potential of the indifferent electrode could be expressed by the general equation [H₂O]/[H₂] [OH^–] which is different from the one expected on the basis of a Nernstian behaviour of the theoretical overall system 2H₂O+2e=H₂+2OH^–.The experimental findings are discussed in terms of mechanistic models involving the actual electrode surface and the standard potential for the theoretical (reversible) hydrogen electrode is calculated: =–·0V(versus Ag/Ag⁺ 0·07 M).     

Comparison between the impedance spectra of Li/SOCl2 batteries obtained using the time and the frequency domain measurement techniques

A comparison between the impedance spectra of Li/SOCl₂ batteries obtained in the time and frequency domains is reported. It is demonstrated that by averaging over several responses the accuracy in the time domain is greatly improved. On the other hand, it was found that the time domain technique caused nonlinearity in the system response even at very small amplitudes of excitation (for example corresponding to a potential drop of 30 mV). The method is useful for routine characterization of the quality of galvanic cells in industrial production. The accuracy compared with market-available impedance spectrometers operating in the frequency domain is satisfactory (±10%), the price being much lower.Nomenclature g _i parameters of model frequency response - g _id parametersg _i obtained by deconvolution - g _ir parametersg _i obtained by frequency domain method - H frequency response - H _m model frequency response - H _r reference frequency response - i(t) excitation current - I() Fourier transform of thei(t) - Im imaginary part - j imaginary unit - M Number of independent measurements - N number of samples - Re real part - R resistance - R ₀ ohmic resistance - T sampling time - u(t) response voltage - U() Fourier transform ofu(t) - dispersion factor - angular frequency - () phase spectrum - _a relative amplitude error - _gi relative error ofg _i - average relative amplitude error - _p relative phase error - average relative phase error - ₀ mean relaxation time     

Fundamental studies on a new concept of flue gas desulphurization

A new process for removal of sulphur dioxide from waste gases is proposed consisting of both electrochemical and catalytic sulphur dioxide oxidation. In the catalytic step a part of the sulphur dioxide is oxidized by oxygen on copper producing sulphuric acid and copper sulphate. The other part is oxidized electrochemically on graphite. The cathodic reaction of this electrolysis is used for recovering the copper dissolved in the catalytic step. The basic reactions of this process have been studied experimentally in detail. It has been shown that sulphur dioxide can be electrochemically oxidized on carbon electrodes to sulphuric acid with high current efficiency. The reaction rate of the electrochemical copper deposition is increased by dissolved sulphur dioxide in the electrolyte. The catalytic oxidation of sulphur dioxide on copper has been investigated for different sulphur dioxide concentrations and temperatures. The ratio of the reaction products, sulphuric acid and copper sulphate, varies over a wide range depending on the experimental conditions.Nomenclature SO₂ concentration (gas phase) (vol % SO₂) - SO₂ concentration (electrolyte) (g l^–1) - E potential vs saturated calomel electrode (V) - E _s specific energy consumption (W g^–1 SO₂) - F Faraday constant (A s^–1 mol^–1) - i current density (mA cm^–2) - molecular weight (g mol^–1) - T temperature (° C) - U _c cell voltage (V) - v _e number of electrons being transferred - space-time yield of SO₂-oxidation (g SO₂ h^–1 dm^–3) - _cu space-time yield of Cu-corrosion (g Cu h^–1 dm^–3) - ratio - fractional conversion of SO₂ - current efficiency for SO₂ oxidation     

On the preparation and properties of CuZSM-5 catalysts for NO decomposition

Equilibrium exchange isotherms were determined for the exchange of Cu²⁺ with NaZSM-5 at varying Cu(Ac)₂ concentrations in solutions of constant volume and zeolite weight. At low Cu²⁺ levels the solid scavenged all the copper ions. When copper could be detected in the equilibrated solutions, overexchange was observed. The extent of overexchange was higher at pH 6 than at pH 4. These results were analyzed in relation to catalytic activity.On leave from the Central Institute for Chemistry, Hungarian Academy of Sciences, H1525 Budapest, Hungary.     

Weak Gel Behaviour of Poly(vinyl alcohol)-Borax Aqueous Solutions

Thermal transition of PVA-borax aqueous gels with a PVA concentration of 60 g/L and a borax concentration of 0.28 M was investigated at temperatures ranging from 15 to 60C using static light scattering (SLS), dynamic light scattering (DLS), and dynamic viscoelasticity measurements. Three relaxation modes, i.e. two fast and one slow relaxation modes, were observed from DLS measurements. Two fast relaxation modes located around 10^–310¹ sec, with one fast mode (_f1) being scattering vector q-dependent and the other fast mode (_f2, with _f2>_f1) being q-independent. The _f1 mode was attributed to the gel mode whilst the _f2 mode could be due to the hydrodynamics of intra-molecular hydrophobic domains formed by uncharged segments of polymer backbones. The slow relaxation mode with relaxation time located around 10¹10³ sec in DLS data was due to the motion of aggregated clusters and was observed only at temperatures above 40C. The amplitude and relaxation time of slow mode decrease as temperature is increased from 40 to 60C. At temperatures below 40C, no slow relaxation mode was observed. The SLS measurements showed PVA-borax-water system had fractal dimensions D _f2.4 and D _f2.0 as temperature was below and above 40C, respectively. The simple tilting test indicated gel behaviour for the PVA-borax aqueous system at temperatures below 40C with a creep flow after a long time exposure in the gravity field. But the dynamic viscoelasticity measurements demonstrated a solution behaviour for PVA/borax/water at temperatures below 40C, the critical gel point behaviour for G() and G() was not observed in this system as those reported for chemical crosslinked gels. These results suggest that the PVA-borax aqueous system is a thermoreversible weak gel.     

Mark-Houwink-Sakurada coefficients for conventional poly(methyl methacrylate) in tetrahydrofuran

Summary Intrinsic viscosities [] in tetrahydrofuran (THF) at 30°C are reported for ten narrow molecular weight distribution poly(methyl methacrylate) (PMMA) samples covering nearly two orders of magnitude in molecular weight. By combining the viscosity results with absolute weight-average molecular weights determined via low-angle laser light scattering (LALLS) experiments, we have accurately determined the Mark-Houwink-Sakurada (MHS) parameters for this polymer-solvent pair (K=7.56x10⁵ and a=0.731, when [] is in dL g^-1).     

Isotopic exchange between H2 and D2 by the Rideal-Eley mechanism

The rate of the reaction, H₂+D₂ 2HD, is very rapid at –160 °C on the catalyst Cp₂Th-(CH₃)₂/dehydroxylated Al₂O₃, activated in H₂+D₂ and believed to contain supported Cp₂ThH⁺(Cp = ⁵-pentamethylcyclopentadienyl). Even at –195 °C, the turnover frequency is greater than 0.1 sec^–1 at atm. Strong evidence is adduced that the exchange proceeds by a Rideal-Eley process, i.e. by a four-center transition state involving Th-H+D-D.     

Sex pheromone components of corn stalk borerSesamia nonagriodes (Lef.) isolation,identification, and field tests

Z-11-Hexadecenyl acetate (Z11–16OAc), dodecyl acetate (12OAc),Z-11-hexadecenal (Z11–16Aid), andZ-11-hexadecenol (Z11– 16OH), were found in pheromone gland extracts of femaleSesamia nonagriodes (Lef.) [Lepidoptera: Noctuidae]. These four components were also present in airborne volatiles collected from calling virgin females in a 651889 ratio. Hexadecyl acetate (16OAc) was also detected but found to be inactive. The identification was based on multicolumn GC analysis, mass spectrometry, and field activity.Z11–16OAc is the major sex pheromone component; the addition of the secondary components individually decreased male captures. The blend of the four synthetic components in 691588 ratio was highly attractive to males; 200 g per trap was the most effective concentration in field tests.Lepidoptera: Noctuidae     

Mass transfer at the electrodes of the ‘falling-film cell’

In the falling-film cell the electrolyte flows as a thin film in the channel between an inclined plane plate and a sheet of expanded metal which work as electrodes. The present work gives the mass transfer coefficients at both electrodes; the experimental variables are the electrolyte flow-rate, the angle of inclination of the channel and the interelectrode distance. The results allow three different flow regimes to be characterized. At low flow rates, there exists a particular regime where capillary effects are present; in this regime the mass transfer coefficient decreases with increasing flow rate, which is interesting from the point of view of possible industrial electrolytic applications.Nomenclature b width of the inclined channel - D diffusion coefficient - d interelectrode distance - e _m mean film thickness - Grashof number, based ond - Grashof number, based onL - ¯k overall mass transfer coefficient, defined by Equation 9 - L electrode length - Q _v volumetric flow rate - volumetric flow rate per unitQ _vl width of channel - Reynolds number - Schmidt number - Sherwood number, based ond - Sherwood number, based onL - mean velocity of the liquid film - inclination angle of the channel with respect to the horizontal - kinematic viscosity of them electrolyte     

Temperature programmed oxidation of Cu/ZnO catalysts with N2O: an attempt for characterization of copper catalysts

For characterization of the surface structure of metallic copper formed on the support, temperature programmed oxidation (TPO) with N₂O was carried out over various Cu/ZnO catalysts. Four peaks of the N₂ formation (, , and ) were observed at 223, 400, 545 and 600 K in the TPO runs. The average copper crystallite size estimated from the sum of the amount of - and -peaks agreed fairly with those determined by X-ray diffraction and transmission electron microscopy. It was concluded that - and -peaks resulted from the oxidation of metallic copper atoms on the steps, corners and/ or defect sites, and on the flat sites of the surface of copper crystallites, respectively, while - and -peaks resulted from the bulk oxidation of copper.     

Properties ofSrMO 3-δ(M=Fe,Co) as oxygen electrodes in alkaline solution

Strontium ferrates and cobaltates with compositions SrFeO_3- (0.060.40) and SrCoO_3- (0.040.30) were synthesized. The dependence of the oxygen electrode properties on the value was examined in 1 mol dm^–3 KOH solution. In the SrFeO_3- series, the samples with 0.24<<0.29, showed the highest activity in both oxygen evolution and reduction reactions. In contrast, no strong dependence on the value was observed in SrCoO_3-, which also showed a high catalytic activity for oxygen evolution.     

Terpolymerization: A Review

The terpolymer, poly (styrene-acrylonitrile-linalool) has been synthesized by free radical solution polymerization of the electron-donating monomers, linalool (optically active) (LIN) and styrene (STY) with the electron-accepting monomer, acrylonitrile (AN) using benzoyl peroxide (BPO) as an initiator and xylene as diluent at 75°C for 40 minutes. The system follows ideal kinetics. Rp [BPO]^0.5 [LIN]^1.0 [STY]^1.0 [AN]^1.0. ¹H-NMR spectrum of terpolymer has peaks at 7.8–8.0 due to –OH group of LIN and at 7.0–7.7 due to phenyl group of styrene. ¹³C-NMR spectrum of terpolymer has peaks at ppm = 119–120 of –CN, ppm = 129–136 of C₆H₅ and ppm = 75–77 of –C–OH. Bands at 3075 cm^–1, 2240 cm^–1 and at 3500 cm^–1 are observed in the FTIR spectrum of terpolymer, indicates the presence of phenyl, cyanide and hydroxy group respectively. The reactivity ratios, determined by the Kelen–Tüdös method [r ₁ for AN and r ₂ for (LIN + STY)] are 0.11 and 0.005 respectively. It is concluded that the system agrees with theoretical treatment and gives the relative reactivity ratio k ₁₂/k ₁₃=0.748 by treatment of the free radical propagating mechanism. The overall activation energy is 38 kJ/mol. The molecular weight of terpolymer is determined by gel permeation chromatography technique. The value of _w/ > _n is 1.36.     

Effects of crystallinity and supermolecular formations on the interfacial shear strength and adhesion in GF/PP composites

Aim of this study was to screen the morphological effects on the interfacial shear strength (i) in glass fibre (GF) reinforced isotactic polypropylene (iPP) model composites. i was determined by a modified single fibre pull-out technique. It was established that the relation between i (5–6 MPa) and the yield stress of the iPP (y30 MPa) is at about 1:6 and that the i values were not influenced by the mophological superstructure set under isothermal crystallization conditions. Increased i was only observed when specimens were produced non-isothermally, by quenching (i9 MPa). This improvement could not be related to thermal shrinkage stresses. The enhancement in i was attributed to better wetting and improved adhesion due to the enlarged amorphous PP (aPP)-phase. A schematic adhesion model considering the wetting behaviour of aPP and iPP was proposed.     

Physicochemical properties of electrodepositedβ-lead dioxide: Effect of deposition current density

The influence of current density on the coulometric efficiency of -PbO₂ deposition in 0.5 M cM lead nitrate, the nonstoichiometry, impurity of -PbO₂ and voltammetric double layer capacitance have been studied. While the coulometric efficiency is about 95% at current densities less than 30 mA cm^–2, it decreases at higher current densities. The oxygen deficiency, , in -PbO_2- has been found to be invariant with the current density. X-ray diffraction studies provide a linear decrease in the weight percent of -PbO₂ as an impurity in the -PbO₂ with increase in current density, and the -PbO₂ is found to be absent at 100mA cm^–2 or higher. The estimated double layer capacitance from the cyclic voltammograms recorded in the potential range 0.70–1.10V, increases with deposition current density, indicating enhanced surface area.     

Numerical simulation of non-Newtonian jets emanating from a converging cone

The effects of the rheological properties on the fluid motion of non-Newtonian jets emanating from a converging cone have been investigated theoretically. Three typical non Newtonian fluid models have been considered; i.e. the power-law fluid, the modified Bingham ngham fluid and the Oldroyd-B fluid. The effects of five parameters on the flow field are analyzed in detail; these parameters are: the contraction ratio of the radius of the cone far upstream to that at the cone exit L; the converging angle of the cone 6; the power-law index n; the Bingham number Bn and the Weissenberg number We. The Galerkin finite-element method incorporated with the upwind scheme was applied to solve the flow problems numerically. Full Newton iteration was used to solve the flow fields and the free-surface positions of power-law and modified Bingham fluids. However, the free-surface position of the Oldroyd-B fluid has to be updated by kinematic iteration to avoid numerical oscillations.Notation a one-half of the cone gap at the cone exit - Bn Bingham number, Eq. (8) - b radius of the cone far upstream - C_o jet swell ratio, Eq. (2) - D rate of the deformation tensor, Eq. (7) - I unit tensor - L contraction ratio, Eq. (2) - m exponent factor of the modified-Bingham fluid, Eq. (8) - n power-law index - n unit normal vector - p, pressure, dimensional and dimensionless - P_atm environmental pressure - U average fluid speed at the cone exit - v, velocity vector, dimensional and dimensionless - We Weisenberg number, Eq. (9) Greek letters viscosity ratio of polymer to solution - one-half of the jet thickness far downstream - _o Newtonian viscosity or consistency of power law fluid - converging angle, Figure 1 - relaxation time of the Oldroyd-B fluid - _D second invariant of tensor D, Eq. (7) - total stress tensor, Eq. (5) - , stress tensor, dimensional and dimensionless - _E elastic stress tensor, Eq. (9) - _V stress tensor, Eqs. (6), (8) and (9) - _o apparent yield stress     

Comportement électrochimique des variétés alpha et beta PbO2 et influence de l'antimoine sur leur reactivité électrochimique en milieu H2SO4, 8N

Résumé L'expérience a montré qu'il est possible d'obtenir par l'oxydation anodique des variétés- et-PbO₂ parfaitement pures au point de vue cristallographique, et que la réduction de-PbO₂ se déroule à un potentiel plus élevé et plus constant que celui observé sur-PbO₂. La réactivité électrochimique de-PbO₂ est plus importante que celle de-PbO₂. L'introduction de Sb dans les réseaux cristallins de ces variétés diminue fortement leur cristallinité et dans le cas de-PbO₂ on obtient toujours simultanément- et-PbO₂. Du point de vue réactivité électrochimique, l'accroissement dû à la présence de Sb est de l'ordre de 33%.

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The results demonstrate the possibility of preparing through anodic oxidation rigorously pure, from the crystallographic point view,- and-PbO₂ phases, and that the reduction of-PbO₂ takes place at a potential which is more positive and more constant than the one obtained with-PbO₂. In a battery, the electrochemical reactivity of-PbO₂ is more important. The introduction of Sb into the lattice of these forms of PbO₂ decreases their crystallinity, and for the case of-PbO₂ we obtained simultaneously- and-PbO₂. Their electrochemical reactivity can increase by about 33%.

     

Studies on nonisothermal solid state galvanic cells — effect of gradients on EMF

An expression for the EMF of a nonisothermal galvanic cell, with gradients in both temperature and chemical potential across a solid electrolyte, is derived based on the phenomenological equations of irreversible thermodynamics. The EMF of the nonisothermal cell can be written as a sum of the contributions from the chemical potential gradient and the EMF of a thermocell operating in the same temperature gradient but at unit activity of the neutral form of the migrating species. The validity of the derived equation is confirmed experimentally by imposing nonlinear gradients of temperature and chemical potential across galvanic cells constructed using fully stabilized zirconia as the electrolyte. The nature of the gradient has no effect on the EMF.Nomenclature J _i flux of speciesi - X _i generalized forces - L _ij Onsagar coefficient - ₁ electrochemical potential of ions - ₂ electrochemical potential of electrons - T absolute temperature - U ₁ ^* total energy of transfer of the ion - partial molar enthalpy of the ion - Q ₁ ^* heat of transport of the ion - Z ₁ charge on the ion - F Faraday constant - electrostatic potential - ₂ chemical potential of the electron - ₁ chemical potential of the ion - partial entropy of the ion - E _SE EMF developed across the solid electrolyte - E _Pt EMF developed across the platinum lead - ( ₂)_Pt chemical potential of electrons in platinum - partial entropy of electrons in platinum - (Q ₂ ^* )_Pt heat of transport of electrons in platinum - E _cell EMF developed across the whole cell - chemical potential of oxygen - chemical potential of oxygen in its standard state - R universal gas constant - partial pressure of oxygen - relative chemical potential of oxygen - _M relative chemical potential of metal M - a _M activity of metal M     

Synthesis and characterization of polyacrylonitrile grafted with poly(2,6-dimethyl-1,4-phenylene oxide)

Summary Free radical copolymerization of acrylonitrile (AN, M₁) with poly(2,6-dimethyl-1,4-phenylene oxide)--vinylbenzyl ether (PPO-VBE, M₂, _n + 4200g/mol, _w/ _n + 1.04) was performed at 60°C in either a mixture of N,N-dimethylformamide/toluene or tetrahydrofuran, using 2,2-azoisobutyronitrile (AIBN) as initiator. The characterization of the resulting polyacrylonitrile grafted with poly(2,6-dimethyl-1,4-phenylene oxide) (PAN-g-PPO) was performed by 200 MHz ¹H-NMR spectroscopy and solubility.