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1.
Summary The isobutylene polymerizations in the presence of BCl3 were carried out in dichloromethane ([M]=7 mol/l) at-20°C in the presence and absence of PVC. The products of polymerizations in the absence of PVC are oligoisobutylenes with a narrow molecular weight distribution ; their structure was analyzed by 1H-NMR spectroscopy. In addition to the signals assigned to known unsaturated terminal structures [ 4.62 and 4.82-CH2C(CH3)=CH2, 5.12-CH=C(CH3)2], a new intense signal was found at 5.09 ppm and assigned to the structure-CH=C(CH3)CH2CH3. A mixture of isobutylene homopolymers and PVC grafted with isobutylene (approx. 9.5% wt. isobutylene grafted) is formed in the presence of PVC.  相似文献   

2.
Copper(II) polymer complexes of empirical formula [Cu(ligand)2X2] (where X = Cl, Br, I, NO3, and SO4) and [Cu(ligand)(CH3COO)2] have been prepared with poly(3-phenylacrylidine semicarbazone). All the polymer complexes prepared have been characterized by elemental analysis, magnetic moment, conductance, IR, electronic, 1H-NMR, and electronic paramagnetic resonance spectral studies. The polymer complexes [Cu(ligand)2X2] and [Cu(ligand) (CH3COO)2] may have tetragonal symmetry while the [Cu(ligand)2( SO4)2] may be five-coordinate trigonal bipyramidal in structure. All complexes exhibit normal magnetic moments corresponding to one unpaired electron except [Cu(ligand)(CH3COO)2] which shows a subnormal magnetic moment. EPR spectra of the polymer complexes have been studied with a view to assigning their stereochemistries. Various EPR parameters have been calculated. The g, A, G values for all the polymer complexes are consistent with a tetragonal 15 and trigonal bipyramidal 6 stereochemistry in the Cu(II) polymer complexes of homopolymer.  相似文献   

3.
A series of poly(ferrocenylsilane)s containing chloroalkyl side chains of increasing length is reported. By reacting fcLi2· tmeda with Cl2SiMeR, the corresponding [1]ferrocenophanes were prepared (2a, R=CH2Cl; 2b, R=CH2CH2Cl; and 2c, R=CH2CH2CH2Cl). Transition metal-catalyzed or thermal ring-opening polymerization (ROP) of these monomers yielded the polyferrocenes 3a, 3b, and 3c. The chlorine substituents of polymers 3a and 3b were unreactive toward nucleophilic substitution. In contast, polymer 3c could be reacted with 4-dimethylaminopyridine in DMF to afford the water-soluble poly(ferrocenylsilane) 4. This represents a new method for the preparation of water-soluble polyferrocenes.  相似文献   

4.
Summary Phenylacetylene could be polymerized by (mesitylene)W(CO)3 in CCl4 to give a polymer with 12,000 in ca. 80% yield. UV irradiation was unnecessary unlike the W(CO)6–CCl4-h catalyst. The present polymerization did not proceed in toluene. The (mesitylene)W(CO)3 catalyst afforded high molecular weight polymers from phenylacetylenes bearing bulky substituents (e.g., Me3Si and CF3) at the ortho position. The Mo counterpart, (mesitylene)Mo(CO)3, catalyzed the polymerization of 1-chloro-2-phenylacetylene and 1-chloro-1-octyne to provide high molecular weight polymers . Catalytic amounts of Lewis acids accelerated the polymerization of phenylacetylene by (mesitylene)W(CO)3, but decreased the polymer molecular weight; this polymerization proceeded not only in CCl4 but also in toluene.  相似文献   

5.
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  相似文献   

6.
Summary The efficient synthesis of symmetrical telechelic polyisobutylenes carrying CH2C(CH3)2Cl groups at either end of the molecule, , has been accomplished by rapid living polymerization using aromatic di-tert.-ether/BCl3 initiator system in CH3Cl at –70°. The living nature of the polymerization was demonstrated by linear Mn versus amount of PIB formed (WPIB) plots starting at the origin. The effect of temperature and solvent composition (polar/nonpolar) on the polymer structure has been investigated. Undesirable indanyl end groups which form during polymerizations carried out at –30° and –50°C can be eliminated by decreasing the temperature to –70°C. The apparent activation energy differences have been determined in the –30 to –70°C range at different polar/nonpolar solvent compositions: Ea of decreases from 2.6 to 1.0 kcal/mole by decreasing the polarity of the medium from 100% CH3Cl to a 60/40 v/v CH3Cl/hexanes mixture.  相似文献   

7.
The potentiometric behaviour of the hydrogen electrodes (Pt or Au) H2O-H2, OHhas been investigated in molten (Na0·5, K0·5)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).  相似文献   

8.
A series of metal-containing vinylic monomers of the type and was homopolymerized using 2,2-azobisisobutyronitrile (AIBN) as the free-radical initiator. These monomers were also copolymerized with styrene in the presence of AIBN. These compounds represent a class of organometallic polymers in which the metal is bonded to the polymer backbone via a metal–carbon bond. The new compounds were characterized by IR and 1H NMR spectroscopy as well as scanning electron microscopy, gel permeation chromatography, and thermoanalytical studies (DSC and TGA). The properties of the new organometallic polymers are discussed.  相似文献   

9.
A complex with the formula [CuL(H2O)2]{[CuL][Fe(CN)6]}2·2H2O, where L=3,10-bis(2-hydroxyethyl)-1,3,5,8,10,12-hexaazacyclotetradecane, has been synthesized and crystallographically characterized. The structure is composed of a one-dimensional zigzag chain of units, and [CuL(H2O)2]2+ units. The one-dimensional zigzag chain extents through linkages. The adjacent two polymer chains are linked by the hydrogen bonding between [CuL(H2O)2]2+ and [Fe(CN)6]3–, forming a 3D supramolecular structure with inner hydrophilic channels. Magnetic susceptibility measurements show no exchange interaction between the Cu(II) and Fe(III) ions due to the longer (axial) bond length.  相似文献   

10.
11.
Many electrochemical processes suffer in varying degrees from mass transfer limitations. These limitations may require operation at considerably less than economic optimum current densities. Mass transfer to a surface may be considerably enhanced by insertion of turbulence promoters in the fluid flow path near the affected surface.An instrument was developed to measure local current densities in the hydrodynamically very difficult region near the turbulence promoter. A general method for the relative evaluation of hydrodynamic conditions has been developed. Generalization of the data permits optimization of hydrodynamic cell design using the promoter shapes investigated.

Notation

Symbols A Coefficient for cell power costs, $ m2 (As)–1 - A c Cell area, m2 - a Constant in Equation 4 - B Coefficient for area-proportional costs, $ A (m2 s)–1 - C Coefficient for pumping power costs, $ A (m2 s)–1 - C b Bulk concentration, kg mol m–3 - C bi Inlet bulk concentration, kg mol m–3 - C e Energy cost, $ (Ws)–1 - C i Interfacial concentration, kg mol m–3 - ¯C s Amortized area cost, $ (m2 s)–1 - D Current—density-insensitive costs, $ s–1 - D e Equivalent diameter, m - D Diffusion constant, m2 s–1 - e Current efficiency - F d Cell feed rate, m3 s–1 - F 96.5×106 A s kg eq–1 - g Channel width, m - h Channel height, m - i Current density, A m–2 - i opt Economic optimum current density, A m–2 - K Total costs of running cell, $ s–1 - (K–D)ideal Total sensitive costs under hydrodynamically ideal conditions, $ s–1 - k c Convective mass transfer coefficient, m s–1 - L Total length of flow path, m - l Promoter spacing, m - N Mass flow rate to surface due to convection, kg mol m2 s–1 - n e Number of electrons transferred in electrode reaction - P c Power required by cell, W - P/L Average pressure gradient in channel, N m–3 - R av Effective cell resistance, m2 - S Open channel cross-section, m2 - S 0 Minimum channel cross-section at promoter, m2 - s i Stoichiometric coefficient of species i - t i Transport number of species i in solution - ¯t i Effective tranport number of species at polarized surface - V Average fluid velocity, m s–1 - x Distance from inception of concentration disturbance, m - 1 Electrical power conversion efficiency - 2 Pumping power conversion efficiency - Solution viscosity, kg (m s)–1 - Solution density, kg m–3 Dimemionless groups Fanning friction factor - Reynolds number - R h/g Channel aspect ratio - D e/l Promoter frequency - S/S 0 Contraction coefficient - Sherwood number - Degree of reaction - Dimensionless total sensitive - Dimensionless current density - Energy cost ratio  相似文献   

12.
Atomic Force Microscopy (AFM) images have been recorded from the surfaces of platelet type monocrystals of linear alkanes, n-tritriacontane, C33H68, and n-hexatriacontane, C36H74. Structural details have been revealed in the range from several hundreds of nanometers down to the atomic scale. High resolution AFM micrographs of the linear alkanes show a regular pattern of elevations characterized by two main periodicities: aAFM=.70±.02 nm, bAFM=.52±.05 nm, , and aAFM=.79±.05 nm, bAFM=.61±.05 nm, , for C33H68 and C36H74 respectively. This structure is in fair agreement with the orthorhombic subcell of the bulk structure as confirmed by electron diffraction. Further, AFM results are in accordance with an orthorhombic unit cell for C33H68, and a monoclinic one for C36H74 under investigation. Consequently, the elevations in the AFM images can be assigned to individual methyl groups, which form the surface layer of a paraffine crystal. A regular surface structure has also been observed in AFM images of platelet crystals of cyclic alkanes, cyclooctatetracontane (CH2)48, and cyclodoheptacontane (CH2)72. In these cases, the periodicities are characterized by aAFM=1.10±.01 nm, bAFM=.85±.01 nm, yAFM=89±1o, and aAFM=1.11±.06 nm, bAFM=.91±.05, and , for (CH2)48 and (CH2)72, respectively. The images are consistent with the arrangement of the adjacent reentry folds obtained from crystallographic data.Herrn Prof. Dr. Harald Cherdron zu seinem 60. Geburtstag herzlich gewidmet  相似文献   

13.
The influence of temperature in the range 25 to 80°C on the dissolution of tin was investigated in an acidic solution at pH4 containing 0.1 to 1m NaCl. The corrosion current is slightly dependent on both the temperature and the Cl ion concentration. The main dissolution characteristics of tin are
  相似文献   

14.
Conclusions Using the method of pure bending, we studied the steady-state (stationary) creep of the single-phase and the two-phase ceramics belonging to the ZrO2-CaO system in the 1300–1600°C and 2–32 N/mm2 ranges; the CaO content of the experimental ceramics varied from 12 up to 50%. The ratio of the strain rates in the two-phase region of the phase diagram (a mixture of the cubic solutions of ZrO2 and calcium zirconate CaZrO3) amounts to at 1400°C and 4 N/mm2 and 1:5:3.8 at 1500°C and 2 N/mm2.The stress parameters and the activation parameters of creep (the stress exponent and the effective activation energy) were determined and their dependence on the phase composition of the experimental specimens was evaluated.The possible deformation mechanisms during the creep regime were discussed. It was shown that in the single-phase specimens consisting of cubic solid solutions, the mechanisms of diffusional-plastic (viscous) flow in the body of the grains, conservative dislocation slip, and creep induced by the formation of cracks operate.The values of the stress exponent of the two-phase specimens (n 1.3·1.6) indicate the occurrence of grain boundary sliding or the crack-induced creep mechanism. In the ceramic consisting of calcium zirconate, the combination of a relatively high activation energy for creep and the parameter n 2 indicates the dislocation nature of the high-temperature deformation process.Translated from Ogneupory, No. 2, pp. 7–12, February, 1989.  相似文献   

15.
Summary Poly(N-ethyl 3.7-phenothiazinediyl) (1) and poly (N-ethyl 3.7-phenothiazinediyl-co-acetylene) (2) were synthesized by homo- and copolycondensation of 3.7-dibromo N-ethylphenothiazine and 1.2-dibromoethene using a Grignard reaction and NiCl2 or NiCl2.2PPh3 as catalyst. Polymers are soluble in common organic solvents and after doping with iodine have an electrical conductivity of 10–7 –10–6 cm–1.  相似文献   

16.
A mathematical model is presented for the optimization of the hydrogen-chlorine energy storage system. Numerical calculations have been made for a 20 MW plant being operated with a cycle of 10 h charge and 10h discharge. Optimal operating parameters, such as electrolyte concentration, cell temperature and current densities, are determined to minimize the investment of capital equipment.Nomenclature A ex design heat transfer area of heat exchanger (m2) - a F electrode area (m2) - heat capacity of liquid chlorine (J kg–1K–1) - heat capacity of hydrogen gas at constant volume (J kg–1 K–1) - c p,hcl heat capacity of aqueous HCl (J kg–1 K–1) - C $acid cost coefficient of HCl/Cl2 storage ($ m–1.4) - C $ex cost coefficient of heat exchanger ($ m–1.9) - C $F cost coefficient of cell stack ($ m–2) - cost coefficient of H2 storage ($ m–1.6) - C $j cost coefficient of equipmentj ($/unit capacity) - C $pipe cost coefficient of pipe ($ m–1) - C $pump cost coefficient of pump ($ J–0.98 s–0.98) - E cell voltage (V) - F Faraday constant (9.65 × 107 C kg-equiv–1) - F j design capacity of equipmentj (unit capacity) - G D design electrolyte flow rate (m3 h–1) - heat of formation of liquid chlorine (J kg-mol–1 C12) - H f 0 ,HCl heat of formation of aqueous HCl (J kg-mol–1HCl) - H m total mechanical energy losses (J) - I total current flow through cell (A) - i operating current density of cell stack (A m–2) - L length of pipeline (m) - N number of parallel pipelines - nHCl change in the amount of HCl (kg-mole) - P pressure of HCl/Cl2 storage (kPa) - p 1 H2 storage pressure at the beginning of charge (kPa) - p 2 H2 storage pressure at the end of charge (kPa) - –Q ex heat removed through the heat exchanger (J) - R universal gas constant (8314 J kg-mol–1 K–1) - the solubility of chlorine in aqueous HCl (kg-mole Cl2 m–3 solution) - T electrolyte temperature (K) - T 2 electrolyte temperature at the end of charge (K) - T max maximum electrolyte temperature (K) - T min minimum electrolyte temperature (K) - t final time (h) - t ex the length of time for the heat exchanger operation (h) - Uit ex overall heat transfer coefficient (J h–1 m–2 K–1) - V acid volume of HCl/Cl2 storage (m3) - } volume of H2 storage (m3) - v design linear velocity of electrolyte (m s–1) - amount of liquid chloride at timet (kg) - amount of liquid chlorine at timet 0 (kg) - w hcl amount of aqueous HCl solution at timet (kg) - W p design brake power of pump (J s–1) - X electrolyte concentration of HCl at timet (wt fraction) - X f electrolyte concentration of HCl at the end of charge (wt fraction) - X i electrolyte concentration of HCl at the beginning of charge (wt fraction) - X 0 electrolyte concentration of HCl at timet 0 (wt fraction) - Y objective function to be minimized ($ kW–1 h–1) - j the scale-up exponent of equipmentj - overall electric-to-electric efficiency (%) - acid safety factor of HCl/Cl2 storage - fractional excess of liquid chlorine - p pump efficiency - average density of HCl solution over the discharge period (kg m–3)  相似文献   

17.
Two new organic–inorganic hybrid compounds [\textCu\textI ( \texten ) 2 ( \textH 2 \textO )] 2 { ( \textSiW\textVI 1 1 \textW\textV 1\textO 40 ) 2 [ \textCu\textII ( \texten ) 2 ( \textH 2 \textO )] 2 [\textCu\textII ( \texten ) 2 ] 2 }·6 \textH 2 \textO [{\text{Cu}}^{\text{I}} \left( {\text{en}} \right)_{ 2} \left( {{\text{H}}_{ 2} {\text{O}}} \right)]_{ 2} \left\{ {\left( {{\text{SiW}}^{\text{VI}}_{ 1 1} {\text{W}}^{\text{V}}_{ 1}{\text{O}}_{ 40} } \right)_{ 2} \left[ {{\text{Cu}}^{\text{II}} \left( {\text{en}} \right)_{ 2} \left( {{\text{H}}_{ 2} {\text{O}}} \right)\left] {_{ 2} } \right[{\text{Cu}}^{\text{II}} \left( {\text{en}} \right)_{ 2} } \right]_{ 2} } \right\}{\cdot}6 {\text{H}}_{ 2} {\text{O}} (1) and (H2 L)2[SiW12O40]·H2O (2) [en = ethylenediamine, L = 1,4-bis(3-pyridinecarboxamido)benzene], have been hydrothermally synthesized and characterized by IR, elemental analyses, TG analysis, and single-crystal X-ray diffraction. Structural analyses indicate that compound 1 exhibits an interesting three-dimensional(3D) cross-like supramolecular network through arrangement of a 1D organic–inorganic hybrid chain { ( \textSiW\textVI 1 1 \textW\textV 1 \textO 40 ) 2 [ \textCu\textII ( \texten ) 2 ( \textH 2 \textO )] 2 [\textCu\textII ( \texten ) 2 ] 2 } 2- . \left\{ {\left( {{\text{SiW}}^{\text{VI}}_{ 1 1} {\text{W}}^{\text{V}}_{ 1} {\text{O}}_{ 40} } \right)_{ 2} \left[ {{\text{Cu}}^{\text{II}} \left( {\text{en}} \right)_{ 2} \left( {{\text{H}}_{ 2} {\text{O}}} \right)\left] {_{ 2} } \right[{\text{Cu}}^{\text{II}} \left( {\text{en}} \right)_{ 2} } \right]_{ 2} } \right\}^{ 2- } . The compound 2 consists of protonated L ligand and [SiW12O40]4− anion. The protonated L ligands have been extended into a 2D network via hydrogen-bonding interactions. The guest [SiW12O40]4− clusters have been incorporated into the square voids of the 2D host network as templates. The electrochemical behavior and electrocatalysis of compound 2 bulk-modified carbon paste electrode (2-CPE) have been studied.  相似文献   

18.
Summary Cationic polymerization of CH2=CH-O-CH2CH2C(COOC2H5)3, a vinyl ether with three pendent esters, initiated by the HI/I2 system in toluene at –40 °C afforded living polymers with a controlled molecular weight ( = 103–104) and a narrow molecular weight distribution ( = 1.1–1.2). The number-average molecular weight of the polymers was directly proportional to monomer conversion and the monomer-to-initiator (HI) feed ratio. The polymers obtained with BF3O(C2H5)2 had a fairly high molecular weight ( 105, 5 × 104) and a broad molecular weight distribution. The triester vinyl ether was similar in reactivity to alkyl counterparts and one order of magnitude more reactive than the corresponding mono- and diester vinyl ethers.  相似文献   

19.
Denitrification rates (d) in a flooded alkaline clay were measured following addition of either to the floodwater, by collecting evolved N2 + N2O in an enclosure in the absence or presence of rice plants. Similar estimates of d were obtained in the treatment when the isotopic composition of the enclosed atmosphere was determined using arc redistribution or direct mass spectrometric analysis. Approximately 90% of the gaseous products of denitrification were physically trapped in the soil five days after addition. Mechanical shaking of the soil-water system was an effective method for releasing entrapped gas. Denitrification showed a marked diurnal variation in both and treatments planted to rice, with higher rates during the day than at night. Measured rates of denitrification were higher in planted than in unplanted pots for both and treatments for normal gas sampling. However, evidence was obtained that this was not a real effect, but was due to release of entrapped gas. Denitrification losses corrected for gas entrapment were estimated at <5% of applied . The 15N mass balance indicated that a much larger amount of applied ammonium (15–25%) was lost by NH3 volatilisation. The rate of denitrification corrected for gas entrapment was similar to the rate of nitrification estimated by inhibition of ammonium oxidation. Although the inhibitors 2-ethynylpyridine and acetylene prevented denitrification by effectively inhibiting nitrification of , the total recovery of 15N in the soil-plant system did not increase. The total recovery of was 7–9% higher in the presence than in the absence of rice.  相似文献   

20.
The infrared stretching frequencies of linear-bonded carbon monoxide on face, edge and corner atoms have been identified with four platinum catalysts. The metal particles were supported on different absorbentia and each having a different average particle size, ranging from about 10 to 200 Å. The values of the various absorption bands correlate linearly with the number of nearest neighbours of the different surface sites (n in C n ). Effects of an interaction between Pt clusters and support on the linear-CO stretching frequency have not been observed. This empirical correlation between and Cn, and the advantages ofin situ Diffuse Reflectance Fourier transform Infrared Spectroscopy in combination with derivative spectrometry opens the possibility to monitor the dispersity of supported platinum in a simple and relatively quick way.  相似文献   

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