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1985 Volume 2 Issue 3
1985, 2(3): 1-5
Abstract:
The relationship between the relaxation behavior of bulk polymer and the processability of the raw rubber of poly (cis-1,4-butadiene) obtained with nickel catalyst has been studied by the method of stress relaxation. The effect of structure factors of rubber chain on the viscoelastic properties of raw rubber was discussed.
The relationship between the relaxation behavior of bulk polymer and the processability of the raw rubber of poly (cis-1,4-butadiene) obtained with nickel catalyst has been studied by the method of stress relaxation. The effect of structure factors of rubber chain on the viscoelastic properties of raw rubber was discussed.
1985, 2(3): 6-11
Abstract:
It was found tbat when THAQ was pretreated with NaNO2 in acid solution, a sharp,symmetric and sensitive peak current of Zr(Ⅳ)-THAQ complex in borate buffer solution was produced at -0.81V(vs.SCE).The height of the peak of the complex was in direct proportion to the concentration of zirconium in the range of 2.0×10-7 to 5.5×10-6M. The limit of the determination was 20 ppb of Zr(Ⅳ).A new oscillographic method for the determination of micro amount of Zr(0.0005%) in steel and alloys has been then developed.The method was simple to operate,nontoxic and the results of the analysis were satisfactory accurate.The composition ratio of Zr(Ⅳ) to THAQ in complexes determined was 1:2 and 1:4.The stability constants of the correspoding complexes calculated as β1=7.1×1010 and β2=8.9×1021. The results showed that the peak current of Zr(Ⅳ)-THAQ is of adsoiption character.
It was found tbat when THAQ was pretreated with NaNO2 in acid solution, a sharp,symmetric and sensitive peak current of Zr(Ⅳ)-THAQ complex in borate buffer solution was produced at -0.81V(vs.SCE).The height of the peak of the complex was in direct proportion to the concentration of zirconium in the range of 2.0×10-7 to 5.5×10-6M. The limit of the determination was 20 ppb of Zr(Ⅳ).A new oscillographic method for the determination of micro amount of Zr(0.0005%) in steel and alloys has been then developed.The method was simple to operate,nontoxic and the results of the analysis were satisfactory accurate.The composition ratio of Zr(Ⅳ) to THAQ in complexes determined was 1:2 and 1:4.The stability constants of the correspoding complexes calculated as β1=7.1×1010 and β2=8.9×1021. The results showed that the peak current of Zr(Ⅳ)-THAQ is of adsoiption character.
1985, 2(3): 12-17
Abstract:
A higher derivative spectrophotometric method for the determination of individual rare earths has been developed. The method described appears quite adequate in terms of rapidity and simplicity and has been applied to the determination of Pr, Nd, Sm, Eu, Dy, Ho, Er and Tm in mixed rare earth samples with satisfactory results.
A higher derivative spectrophotometric method for the determination of individual rare earths has been developed. The method described appears quite adequate in terms of rapidity and simplicity and has been applied to the determination of Pr, Nd, Sm, Eu, Dy, Ho, Er and Tm in mixed rare earth samples with satisfactory results.
1985, 2(3): 18-22
Abstract:
The authors have synthesized methyl tributyltin maleate (MTBTM)and ethyl tributyltin maleate (ETBTM). Two monomers were copolymerized with vinyl acetate (VAc) and styrene (St) alternatively.The copolylmerization conditions, such as temperature,concentration of monomers and solvents were examined.The conversion of coplymerization of MTBTM with was was found up to 88%.Copolymers were characterized by IR, 1H-NMR, elementarl analysis and intrinsic viscosity.Copolymers of MTBTM-VAc, ETBTM-VAc, ETBTM-St and ETBTM-St are soluble in many organic solvents and the first two are transparant elastomers, while the last two are white and brittle solids.
The authors have synthesized methyl tributyltin maleate (MTBTM)and ethyl tributyltin maleate (ETBTM). Two monomers were copolymerized with vinyl acetate (VAc) and styrene (St) alternatively.The copolylmerization conditions, such as temperature,concentration of monomers and solvents were examined.The conversion of coplymerization of MTBTM with was was found up to 88%.Copolymers were characterized by IR, 1H-NMR, elementarl analysis and intrinsic viscosity.Copolymers of MTBTM-VAc, ETBTM-VAc, ETBTM-St and ETBTM-St are soluble in many organic solvents and the first two are transparant elastomers, while the last two are white and brittle solids.
1985, 2(3): 23-28
Abstract:
In this paper the narrow line emision of f→f transition for Eu2+ ion in the system BaF2-xREF3 (RE:rare earths) is reported. When RE=Lu,x=1(at temperature T=300K);RE=Y,x=2(T=300K)‘RE=Sc,x=2(T=77K);RE=La or Gd(T=77K) the narrow line emission was found to be dependent on the temperature (T) and the molar ratio (x) bet ween cations in flouride matrix and the emission became more easier according the order of La, Gd, Sc, Y and Lu. No narrow line emission for Eu2+ ion in BaF2-xREF3 (Ln=lanthanide ions except Pm) was observed, irrespective of whatever molar ratio or temperature was used in the experiments.The narrow line emission (f→f) has been ascribed to the weak crystal field at the site of the Eu2+ ion in fluorides.
In this paper the narrow line emision of f→f transition for Eu2+ ion in the system BaF2-xREF3 (RE:rare earths) is reported. When RE=Lu,x=1(at temperature T=300K);RE=Y,x=2(T=300K)‘RE=Sc,x=2(T=77K);RE=La or Gd(T=77K) the narrow line emission was found to be dependent on the temperature (T) and the molar ratio (x) bet ween cations in flouride matrix and the emission became more easier according the order of La, Gd, Sc, Y and Lu. No narrow line emission for Eu2+ ion in BaF2-xREF3 (Ln=lanthanide ions except Pm) was observed, irrespective of whatever molar ratio or temperature was used in the experiments.The narrow line emission (f→f) has been ascribed to the weak crystal field at the site of the Eu2+ ion in fluorides.
1985, 2(3): 29-33
Abstract:
The transfer of alkali metal ion from water to nitrobenzene facilitated by macrocyclic neutral ionophere has been investigated by voltammetry at the nitrobenzene/water interface. The "potential window" has been extended to the negative direction by using the more hydrophobic salt, tetraphenylarsonium tetraphenylborate, as the base electrolyte in the nitrobenzene phase.
The transfer of alkali metal ion from water to nitrobenzene facilitated by macrocyclic neutral ionophere has been investigated by voltammetry at the nitrobenzene/water interface. The "potential window" has been extended to the negative direction by using the more hydrophobic salt, tetraphenylarsonium tetraphenylborate, as the base electrolyte in the nitrobenzene phase.
1985, 2(3): 34-39
Abstract:
The polymerization of butadiene using neodymium catalysts in combination with organomagnesium-organoaluminum complexes has been investigated. About 40% trans-1,4-polybutadiene was obtained when Ph2Mg was used as one of the catalyst. components Selecting an appropriate formula as well as an order of mixing of components are very important factors for obtaining good yield of high cis-1, 4-polybutadiene.
The polymerization of butadiene using neodymium catalysts in combination with organomagnesium-organoaluminum complexes has been investigated. About 40% trans-1,4-polybutadiene was obtained when Ph2Mg was used as one of the catalyst. components Selecting an appropriate formula as well as an order of mixing of components are very important factors for obtaining good yield of high cis-1, 4-polybutadiene.
1985, 2(3): 40-44
Abstract:
The opmplex oxides Ln1-xSrxMO3 (Ln:rare earth elements.M:Co,Ni,Mn or their mixture), mixed with active carbon, were found to be promising as O2 cathodic reduction catalysts with higher catalytic activity than either of them alone. The steady-state polarization curves of cathodic reduction of oxygen are composedof two Tafel lines with different slopes: b1=-2.303RT/(1+α)F and b2=-2.303RT/αF(α=0.5) for the low c. d.and higher c. d.region respectively. Experiments carried out at different temperatures showed that the system of Ln1-xSrxMO3(10%)-active carbon has a higher catalytic activity for the electrochemical reduction of oxygen in comparison with that of silver(21.2%)-active carbon. The zinc-air cells in which the positive electrodes are made of Ln1-xSrxMO3(10%)-C are found to have specific energy of 340 Wh/kg or 430 Wh/1 and good shelf-life.
The opmplex oxides Ln1-xSrxMO3 (Ln:rare earth elements.M:Co,Ni,Mn or their mixture), mixed with active carbon, were found to be promising as O2 cathodic reduction catalysts with higher catalytic activity than either of them alone. The steady-state polarization curves of cathodic reduction of oxygen are composedof two Tafel lines with different slopes: b1=-2.303RT/(1+α)F and b2=-2.303RT/αF(α=0.5) for the low c. d.and higher c. d.region respectively. Experiments carried out at different temperatures showed that the system of Ln1-xSrxMO3(10%)-active carbon has a higher catalytic activity for the electrochemical reduction of oxygen in comparison with that of silver(21.2%)-active carbon. The zinc-air cells in which the positive electrodes are made of Ln1-xSrxMO3(10%)-C are found to have specific energy of 340 Wh/kg or 430 Wh/1 and good shelf-life.
1985, 2(3): 45-49
Abstract:
A PVC membrane chloride ion-selective electrode with functional polymers as active materials was prepared by thermocompression of its pellet. No plasticizer was added in membrane and no leaching of active materials was experienced. The electrode exhibits Nernstion response in the range from 1×10-1M to 2×10-4M for Cl- and is characterized by very fast response, longer service life, wider pH range in application and small internal resistance. The curves of electrode resistance against preconditional time was obtained. The conditioning of the electrode is related to the constant value of its internal resistance upon gradual decrease with increase of preconditional time.
A PVC membrane chloride ion-selective electrode with functional polymers as active materials was prepared by thermocompression of its pellet. No plasticizer was added in membrane and no leaching of active materials was experienced. The electrode exhibits Nernstion response in the range from 1×10-1M to 2×10-4M for Cl- and is characterized by very fast response, longer service life, wider pH range in application and small internal resistance. The curves of electrode resistance against preconditional time was obtained. The conditioning of the electrode is related to the constant value of its internal resistance upon gradual decrease with increase of preconditional time.
1985, 2(3): 50-54
Abstract:
A series of Pb-Sb alloys containing different amounts of antimony was studied by means of metallography, electro-beam microprobe analysis and cyclic voltametry. The tendency of intercrystalline corrosion of antimony rich phase was observed, and theintercrystalline corrosion was suggested to be caused by the dissolution of Pb(Ⅱ)-compound which appears concentrated in the inter crystalline boundary.
A series of Pb-Sb alloys containing different amounts of antimony was studied by means of metallography, electro-beam microprobe analysis and cyclic voltametry. The tendency of intercrystalline corrosion of antimony rich phase was observed, and theintercrystalline corrosion was suggested to be caused by the dissolution of Pb(Ⅱ)-compound which appears concentrated in the inter crystalline boundary.
1985, 2(3): 55-61
Abstract:
The experimental results of the extraction equlibrium and fractional counter current extraction in system HEH(EHP)-Kerosene-HNO3-(Sm-Gd)(NO3)3 are reported. 96.7% of Sm and more than 99% of Gd were obtained in the raffinate and solvent phaserespectively. From the data obtained in the extraction equlibrium a semiempirical distribution model Di
ai1Zi2aHi3aXjai4Yi5a (i, j=1,2) has been deduced, which is simple in calculation with a certain accuracy. Non-linear equations for the distribution between aqueous and organic phases and the mass equilibrium in each stage for the counter current. extraction were given. The matrix method and FORTRAN program were introduced for the calculation. The calculated values of metal ion concentration, acidity and concentration of the extractants for each stage are in good agreement with the experimental ones.
The experimental results of the extraction equlibrium and fractional counter current extraction in system HEH(EHP)-Kerosene-HNO3-(Sm-Gd)(NO3)3 are reported. 96.7% of Sm and more than 99% of Gd were obtained in the raffinate and solvent phaserespectively. From the data obtained in the extraction equlibrium a semiempirical distribution model Di
ai1Zi2aHi3aXjai4Yi5a (i, j=1,2) has been deduced, which is simple in calculation with a certain accuracy. Non-linear equations for the distribution between aqueous and organic phases and the mass equilibrium in each stage for the counter current. extraction were given. The matrix method and FORTRAN program were introduced for the calculation. The calculated values of metal ion concentration, acidity and concentration of the extractants for each stage are in good agreement with the experimental ones.
1985, 2(3): 62-67
Abstract:
In this paper the kinetics of the laser decomposition process of eight kinds of polymers has been studied. In plotting the decomposition speceis concentration vs.time,a series of similiar S-shape curve was obtained,indicating that there is an analogous kinetic beavior for the polymers decomposed by laser. When the middle and the last portion of the S-shape curves was treated as a first-order and zero-order reactions respectively, the correspoding rate constants were obtained. As the authors considered, the initial stage in the course of the laser radiation is an inductive stage of excitation, on which a certain explanation has been given in the paper. The turning points of the upper portion of the S-shape curves vary with the kinds of polymers studied and could serve as an important parameter,characterizing the structure of the polymers.
In this paper the kinetics of the laser decomposition process of eight kinds of polymers has been studied. In plotting the decomposition speceis concentration vs.time,a series of similiar S-shape curve was obtained,indicating that there is an analogous kinetic beavior for the polymers decomposed by laser. When the middle and the last portion of the S-shape curves was treated as a first-order and zero-order reactions respectively, the correspoding rate constants were obtained. As the authors considered, the initial stage in the course of the laser radiation is an inductive stage of excitation, on which a certain explanation has been given in the paper. The turning points of the upper portion of the S-shape curves vary with the kinds of polymers studied and could serve as an important parameter,characterizing the structure of the polymers.
1985, 2(3): 68-73
Abstract:
In this paper a mono-molecular model of the end-peeling reaction of atactic poly-propylene (APP) was proposed, based on the experimental results, such as iodine value,viscosity and molecular weight distribution of raw material and the products of pyrolysis of APP.An equation of the zero-order reaction of polymer pyrolysis was derived: dmp/dt=K0m0. Another equation for the calculation of the velocity of the mono-molecular first-order pyrolysis reaction, which was considered to be taken place at the final stage of peeling, was also derived: dmp/dt=k1m (where k1=2k0).
In this paper a mono-molecular model of the end-peeling reaction of atactic poly-propylene (APP) was proposed, based on the experimental results, such as iodine value,viscosity and molecular weight distribution of raw material and the products of pyrolysis of APP.An equation of the zero-order reaction of polymer pyrolysis was derived: dmp/dt=K0m0. Another equation for the calculation of the velocity of the mono-molecular first-order pyrolysis reaction, which was considered to be taken place at the final stage of peeling, was also derived: dmp/dt=k1m (where k1=2k0).
1985, 2(3): 74-76
Abstract:
A comparison of air-stability of polyacetylenes(PA) prepared by rare-earth catalyst(Ln-PA) and Shirakawa's catalyst(Ti-PA) through examination of ESR, IR, weight uptake and change of electrical conductivity on long time exposure of these PA films toair is presented. It is found that the cis/trans ratio and conductivity decreased with increasing the exposure time for both types of polymers, but the thermal isomerization rate and the decrease of conductivity of Ln-PA film appeared slower than those of Ti-PA film. Similary, a gradual decrease of conductivity was observed for I2-doped Ln-PA.Spin concentration calculated from ESR intensity decreased with increasing exposure time in the initial stage of oxidation, then increased slightly and decreased. This seems to suggests the occurence of the oxidation reactions (see p.75 eqs. 1, 2).
A comparison of air-stability of polyacetylenes(PA) prepared by rare-earth catalyst(Ln-PA) and Shirakawa's catalyst(Ti-PA) through examination of ESR, IR, weight uptake and change of electrical conductivity on long time exposure of these PA films toair is presented. It is found that the cis/trans ratio and conductivity decreased with increasing the exposure time for both types of polymers, but the thermal isomerization rate and the decrease of conductivity of Ln-PA film appeared slower than those of Ti-PA film. Similary, a gradual decrease of conductivity was observed for I2-doped Ln-PA.Spin concentration calculated from ESR intensity decreased with increasing exposure time in the initial stage of oxidation, then increased slightly and decreased. This seems to suggests the occurence of the oxidation reactions (see p.75 eqs. 1, 2).
1985, 2(3): 77-80
Abstract:
The kinetics of N-MAM synthesized from formaldehyde and acrylamide with NaOH as catalyst in a water solution system and the effect of the amount of catalyst used have been studied. It was found that the reaction rate increased with the increase of reaction temperature and pH of the system. A relative equation between pH and reaction rate constant was obtained. The activation energy of the reaction was calculated.
The kinetics of N-MAM synthesized from formaldehyde and acrylamide with NaOH as catalyst in a water solution system and the effect of the amount of catalyst used have been studied. It was found that the reaction rate increased with the increase of reaction temperature and pH of the system. A relative equation between pH and reaction rate constant was obtained. The activation energy of the reaction was calculated.
1985, 2(3): 81-85
Abstract:
The electroreduction of bromocresol purple was studied by d.c.polarography, differential pulse polarography and cyclic voltammetry. Three or four polarographic reduction waves (peaks) appeared at different pH. First three waves were observed over pH range of 2-9. When pH>9 waves Ⅱ and Ⅲ were overlapped with an appearance of a new wave Ⅳ. Wave Ⅰ was a diffusioncontrolled, irreversible, two electron one, the E1/2(Ep) of which shifted towards more negative potentials with increasing pH. Wave Ⅱ was so small, it could be seen only in differential pulse polarograph.Wave Ⅲ being adsorptive in nature was an irreversible, two-electron one, the E1/2(Ep) of which was independent of pH.Wave Ⅳ was a diffusion controlled, two-electron one. Considering acid-base equilibrium of both oxidized form and reduced form,a formula expressing the relationship between pH and E1/2 has been derived, and the plot of pH-E1/2 for wave Ⅰ has been explained. The mechanism for the reduction of bromocresol purple is discussed.
The electroreduction of bromocresol purple was studied by d.c.polarography, differential pulse polarography and cyclic voltammetry. Three or four polarographic reduction waves (peaks) appeared at different pH. First three waves were observed over pH range of 2-9. When pH>9 waves Ⅱ and Ⅲ were overlapped with an appearance of a new wave Ⅳ. Wave Ⅰ was a diffusioncontrolled, irreversible, two electron one, the E1/2(Ep) of which shifted towards more negative potentials with increasing pH. Wave Ⅱ was so small, it could be seen only in differential pulse polarograph.Wave Ⅲ being adsorptive in nature was an irreversible, two-electron one, the E1/2(Ep) of which was independent of pH.Wave Ⅳ was a diffusion controlled, two-electron one. Considering acid-base equilibrium of both oxidized form and reduced form,a formula expressing the relationship between pH and E1/2 has been derived, and the plot of pH-E1/2 for wave Ⅰ has been explained. The mechanism for the reduction of bromocresol purple is discussed.
