Login In
1992 Volume 9 Issue 2
1992, 9(2): 1-11
Abstract:
The important solid catalysts may be divided into two classes:the one is generally assumed to be multiphasic and multicomponent, e. g, metal and alloy catalysts, it is sofar difficult to elucidate the mechanism of their action. The other is monophasic and with well-defined crystal structure, e. g. zeolite, pillared-clay, polyoxometallate, certain mixed metal oxide etc., the active center of the latter may be envisaged as being dispersed in a spatially uniform fashion throughout its bulk. This point of view is deduced by tracing analogies with the chemistry of enzyme catalysts, focussed largely on their molecular structure and catalytic behaviour.
The important solid catalysts may be divided into two classes:the one is generally assumed to be multiphasic and multicomponent, e. g, metal and alloy catalysts, it is sofar difficult to elucidate the mechanism of their action. The other is monophasic and with well-defined crystal structure, e. g. zeolite, pillared-clay, polyoxometallate, certain mixed metal oxide etc., the active center of the latter may be envisaged as being dispersed in a spatially uniform fashion throughout its bulk. This point of view is deduced by tracing analogies with the chemistry of enzyme catalysts, focussed largely on their molecular structure and catalytic behaviour.
1992, 9(2): 12-17
Abstract:
Forteen novel complexes of lanthanide perchlorate and nitrate with diethylene glycol di(o-hydroxyphenyl) ether (EO2(HOP)2) (EO=ethylene oxide,HOP=o-hydroxyphenyl) have been synthesized and characterized. Compositions of the complexes were comfirmed as Ln·(ClO4)3. EO2(HOP)2·nH2O (Ln=La-Eu, n=10; Ln=Gd, Dy-Tm,Y, n=7),La3(NO3)9·(EO2(HOP)2)2·3H2O and La(ClO4)3·EO2H(OP)2·5H2O respectively. Some properties of the title coordination compounds were investigated by IR-, UV-Spectra,1HNMR and 13C NMR.Effects of eounterion, kinds of solvents and terminal group ligand on eomplexation were also discussed.
Forteen novel complexes of lanthanide perchlorate and nitrate with diethylene glycol di(o-hydroxyphenyl) ether (EO2(HOP)2) (EO=ethylene oxide,HOP=o-hydroxyphenyl) have been synthesized and characterized. Compositions of the complexes were comfirmed as Ln·(ClO4)3. EO2(HOP)2·nH2O (Ln=La-Eu, n=10; Ln=Gd, Dy-Tm,Y, n=7),La3(NO3)9·(EO2(HOP)2)2·3H2O and La(ClO4)3·EO2H(OP)2·5H2O respectively. Some properties of the title coordination compounds were investigated by IR-, UV-Spectra,1HNMR and 13C NMR.Effects of eounterion, kinds of solvents and terminal group ligand on eomplexation were also discussed.
1992, 9(2): 18-22
Abstract:
The dependence of the size and composition of sodium dodecyl sulfonate(AS) micclls on n-pentanol,n-hexanol and n-heptanol has been investigated using the steady-state fluorescence quenching technique. The results show that with the increase of alcohol concentration ([A]) at certain concentration of AS, the average aggregation number (N1) of the mixed alcohol-AS micells decreases to a minimum and then increases with[A], but their average molecular number (NA) increases steadily with[A].The hydrophobic radius of the spherical mixed pentanol-AS, hexanol-AS micells (Rm) has a minimum value on the plot of Rm versus XAm. The longer the alcohol chain the more pronounced this effect.
The dependence of the size and composition of sodium dodecyl sulfonate(AS) micclls on n-pentanol,n-hexanol and n-heptanol has been investigated using the steady-state fluorescence quenching technique. The results show that with the increase of alcohol concentration ([A]) at certain concentration of AS, the average aggregation number (N1) of the mixed alcohol-AS micells decreases to a minimum and then increases with[A], but their average molecular number (NA) increases steadily with[A].The hydrophobic radius of the spherical mixed pentanol-AS, hexanol-AS micells (Rm) has a minimum value on the plot of Rm versus XAm. The longer the alcohol chain the more pronounced this effect.
1992, 9(2): 23-27
Abstract:
Unmixing processes of poly (methyl methacrylate) and poly (vinyl acetate)blends were investigated by using light scattering and optical microscope techniques. The results show that there exist self-similarity and fractal behaviour in phase separation processes. In the late stage of phase separation the asymptotic behavior of scaled structure function F(x) is F(x)~x-6 for large values of x. The fractal dimension of phase structure is about 1.64. These imply that the fractal behaviour of phase structure may result in the scaling feature of structure function.
Unmixing processes of poly (methyl methacrylate) and poly (vinyl acetate)blends were investigated by using light scattering and optical microscope techniques. The results show that there exist self-similarity and fractal behaviour in phase separation processes. In the late stage of phase separation the asymptotic behavior of scaled structure function F(x) is F(x)~x-6 for large values of x. The fractal dimension of phase structure is about 1.64. These imply that the fractal behaviour of phase structure may result in the scaling feature of structure function.
1992, 9(2): 28-32
Abstract:
The molecular sieve CoAPSO-11, cobalt silicoaluminophosphate, and its single crystals have been prepared. The compound consists of P, Al, Co and Si with a molar ratio of 11:11:1:1. The results obtained by SEM, XPS and IR showed that parts of Al and P in frame work are substituted by Co and Si in CoAPSO-11, as compared with AlPO4-11. CoAPSO-11 has a high thermal stability and catalytic activity for isopropylbenzene cracking and methanol conversion.
The molecular sieve CoAPSO-11, cobalt silicoaluminophosphate, and its single crystals have been prepared. The compound consists of P, Al, Co and Si with a molar ratio of 11:11:1:1. The results obtained by SEM, XPS and IR showed that parts of Al and P in frame work are substituted by Co and Si in CoAPSO-11, as compared with AlPO4-11. CoAPSO-11 has a high thermal stability and catalytic activity for isopropylbenzene cracking and methanol conversion.
1992, 9(2): 33-37
Abstract:
Solid state substitution reactions take place between (Co(NH3)4CO3)Cl or (Co(en)2CO3)Cl with NH4SCN at 100℃, with the non-volatized CO32- being substituted outside the inner coordination sphcrc by SCN-. Trans-(Co(NH3)4(NCS)2)Cl is formed in the reaction of (Co(NH3)4CO3)Cl with NH4SCN. However, in the reaction bctwccn(Co(en)2CO3)Cl and NH4SCN, Cis-Co(en)2(NCS)2Cl is at first formed transforming into trans-isomer ultimately. Two reactions are believed to proceed through SN2 mechanism.
Solid state substitution reactions take place between (Co(NH3)4CO3)Cl or (Co(en)2CO3)Cl with NH4SCN at 100℃, with the non-volatized CO32- being substituted outside the inner coordination sphcrc by SCN-. Trans-(Co(NH3)4(NCS)2)Cl is formed in the reaction of (Co(NH3)4CO3)Cl with NH4SCN. However, in the reaction bctwccn(Co(en)2CO3)Cl and NH4SCN, Cis-Co(en)2(NCS)2Cl is at first formed transforming into trans-isomer ultimately. Two reactions are believed to proceed through SN2 mechanism.
1992, 9(2): 38-41
Abstract:
The crystallization behaviour of HDPE/LDPE blend have been studied by using DSC and WAXD techniques.The formation of two types of cocrystallite in blend system depends on the composition of the blend.When the content of HDPE is more than 50%,a HDPE cocrystallite is formed as a result of the entering of LDPE crystallite into HDPE crystalline regions. When the content of LDPE is more than 50%, a LDPE cocrystallite is formed. The changes in Tc, Tm, degree of crystallinity, and parameters of unit cell, observed by DSC and WAXD, showed the presence of HDPE/LDPE cocrystallite. The expansion of interracial regions, was observed from the value of αc, α1, and αb obtained by Raman spectra.
The crystallization behaviour of HDPE/LDPE blend have been studied by using DSC and WAXD techniques.The formation of two types of cocrystallite in blend system depends on the composition of the blend.When the content of HDPE is more than 50%,a HDPE cocrystallite is formed as a result of the entering of LDPE crystallite into HDPE crystalline regions. When the content of LDPE is more than 50%, a LDPE cocrystallite is formed. The changes in Tc, Tm, degree of crystallinity, and parameters of unit cell, observed by DSC and WAXD, showed the presence of HDPE/LDPE cocrystallite. The expansion of interracial regions, was observed from the value of αc, α1, and αb obtained by Raman spectra.
1992, 9(2): 42-45
Abstract:
On the basis of defining a templating index Kt=λ(STA/TPA+), where STA/TPA+ represents the molar ratio of a secondary templating agent(STA) to tetrapropylammonium cation TPA+,λ represents the ratio of the bond length of STA to the bond length of,TPA+. The templating indexes for seven common templating agents (amines and alcohols) in the formation of ZSM-5 molecular sieve were determined. It is shown through synthesis experiments that the templating index can quantitatively describe the effect of templating agents.
On the basis of defining a templating index Kt=λ(STA/TPA+), where STA/TPA+ represents the molar ratio of a secondary templating agent(STA) to tetrapropylammonium cation TPA+,λ represents the ratio of the bond length of STA to the bond length of,TPA+. The templating indexes for seven common templating agents (amines and alcohols) in the formation of ZSM-5 molecular sieve were determined. It is shown through synthesis experiments that the templating index can quantitatively describe the effect of templating agents.
1992, 9(2): 46-50
Abstract:
The isomers of K13[Ln(βi-SiW11O39)2·xH2O (Ln=La, Ce, Pr, Nd, Sm, Gd, Er; βi=β1 and β3) have been prepared and characterized by elemental analysis, polarography,CV, UV-VIS, magnetic susceptibility, magnetic moments determination and thermal analysis. It is showed that the polarographic half wave Potential E1/2 for the new complexes are in the same order as for the βi-SiW11. In β-isomers the E1/2 of βi decreases with the increaoe of the number of unrotated W3O13 group.A linear relationship between E1/2(Ⅰ)and the lowest energy of charge-transfer of the complexes is found. It can be concluded from VIS spectra that Ln(βi-SiW11)2 and Ln(α-SiW11)2 have an identical geometric structure.
The isomers of K13[Ln(βi-SiW11O39)2·xH2O (Ln=La, Ce, Pr, Nd, Sm, Gd, Er; βi=β1 and β3) have been prepared and characterized by elemental analysis, polarography,CV, UV-VIS, magnetic susceptibility, magnetic moments determination and thermal analysis. It is showed that the polarographic half wave Potential E1/2 for the new complexes are in the same order as for the βi-SiW11. In β-isomers the E1/2 of βi decreases with the increaoe of the number of unrotated W3O13 group.A linear relationship between E1/2(Ⅰ)and the lowest energy of charge-transfer of the complexes is found. It can be concluded from VIS spectra that Ln(βi-SiW11)2 and Ln(α-SiW11)2 have an identical geometric structure.
1992, 9(2): 51-55
Abstract:
Polypyrrole (PPy) and polypyrrole containng Methylene Green (MG/PPy)thin-film modified electrodes prepared by electrochemical polymerization may promote heterogeneous electron transfer process of hemoglobin. Using optical thin-layer spectroelectrochemical techniques some electrochemical parameters of hemoglobin on PPy and MG/PPy modified electrode were determined as follows:the electron transfer number n=1.88,formal electrode potential E°'=-0.081V (vs Ag/AgCl) and the heterogeneous electron transfer rate constant ks=1.75×10-5cm/S. The mechanism for the electron transfer reaction of hemoglobin at polypyrrole modified electrode includes:first,the polypeptide chains of hemoglobin were got out of shape by pyrrole, as a result, heme groups were in part exposed; second, owing to the interaction between pyrrole and heme iron, Fe(Ⅱ)was lowered into the porphyrin ring.
Polypyrrole (PPy) and polypyrrole containng Methylene Green (MG/PPy)thin-film modified electrodes prepared by electrochemical polymerization may promote heterogeneous electron transfer process of hemoglobin. Using optical thin-layer spectroelectrochemical techniques some electrochemical parameters of hemoglobin on PPy and MG/PPy modified electrode were determined as follows:the electron transfer number n=1.88,formal electrode potential E°'=-0.081V (vs Ag/AgCl) and the heterogeneous electron transfer rate constant ks=1.75×10-5cm/S. The mechanism for the electron transfer reaction of hemoglobin at polypyrrole modified electrode includes:first,the polypeptide chains of hemoglobin were got out of shape by pyrrole, as a result, heme groups were in part exposed; second, owing to the interaction between pyrrole and heme iron, Fe(Ⅱ)was lowered into the porphyrin ring.
1992, 9(2): 56-59
Abstract:
Complex impedance diagram on Bi2O3-Y2O3 system was investigated using AC impedance method. It was found that Ba2O3-based materials are characteristic of the Warburg impedance. The rate-limiting step of the electrode process at high PO2 is the diffussion of oxygen atom into the solid electrolyte on the triple line. At low PO2 the electrode process is controlled by diffusson as well as by concentration polarization, or controlled only by concentration polarization. Ba2O3-Y2O3 system characterized as a pure oxygen icn conductor at PO2=1×1-10~1×105Pa
Complex impedance diagram on Bi2O3-Y2O3 system was investigated using AC impedance method. It was found that Ba2O3-based materials are characteristic of the Warburg impedance. The rate-limiting step of the electrode process at high PO2 is the diffussion of oxygen atom into the solid electrolyte on the triple line. At low PO2 the electrode process is controlled by diffusson as well as by concentration polarization, or controlled only by concentration polarization. Ba2O3-Y2O3 system characterized as a pure oxygen icn conductor at PO2=1×1-10~1×105Pa
1992, 9(2): 60-61
Abstract:
Poly[1-(trimethylsilyl)-1-propyne](PTMSP) of higher molecular weight was synthesized by cationic polymerization in solution. It has a structurc of[-C(Me)=C(SiMe3)-). It is an amorphous,soluble solid.The permeability to oxygen and selecfivity of O2/N2 Of PTMSP membrane are reported after various modification.
Poly[1-(trimethylsilyl)-1-propyne](PTMSP) of higher molecular weight was synthesized by cationic polymerization in solution. It has a structurc of[-C(Me)=C(SiMe3)-). It is an amorphous,soluble solid.The permeability to oxygen and selecfivity of O2/N2 Of PTMSP membrane are reported after various modification.
1992, 9(2): 62-65
Abstract:
The metal vapor synthesis (MVS) method has been used to prepare Agn/C fuel cell elec. trode catalysts with different Ag contents. The results of XRD and TEM measure ments showed that as Ag content increased the particle size of Agn clusters increased. XRD and XPS data indicated that Ag was mainly in zero.valence state.Agn/C catalysts prepared by MVS method have smaller particles of Agn, more narrow particle size distribution and greater catalytic activities than the Agn/C catalyst with the same content of Ag prepared by conventional method.
The metal vapor synthesis (MVS) method has been used to prepare Agn/C fuel cell elec. trode catalysts with different Ag contents. The results of XRD and TEM measure ments showed that as Ag content increased the particle size of Agn clusters increased. XRD and XPS data indicated that Ag was mainly in zero.valence state.Agn/C catalysts prepared by MVS method have smaller particles of Agn, more narrow particle size distribution and greater catalytic activities than the Agn/C catalyst with the same content of Ag prepared by conventional method.
1992, 9(2): 66-68
Abstract:
Dimethylacetylene (tolane) suffered hydrogenation in the presence of (RCp)2TiCl2. The influences of the catalyst structure on the selectivity of the reaction have been studied.Results indieated that cis-olefins as well as trans-olefins could be obtained by varying R in the catalyst and under suitable reaction conditions.
Dimethylacetylene (tolane) suffered hydrogenation in the presence of (RCp)2TiCl2. The influences of the catalyst structure on the selectivity of the reaction have been studied.Results indieated that cis-olefins as well as trans-olefins could be obtained by varying R in the catalyst and under suitable reaction conditions.
1992, 9(2): 69-72
Abstract:
An empirical correlation between the bond parameters and the hardness of binary crystal ANB8-N was derived:Hv=A((N·Z)/d6)exp(-0.6fi), Hm=0.675 Hv, where Hv-Vikers hardness, Hm-Mohs hardnss,Z-valence,d-bond length (10-10m), N-coordination number, fi-Phillips ionicity,A-constant,8467.5.This empirical correlation was used to calculate the hardness of 66 kinds of compounds. The calculated values of 36 kinds of them are in agreement with the experimental values.
An empirical correlation between the bond parameters and the hardness of binary crystal ANB8-N was derived:Hv=A((N·Z)/d6)exp(-0.6fi), Hm=0.675 Hv, where Hv-Vikers hardness, Hm-Mohs hardnss,Z-valence,d-bond length (10-10m), N-coordination number, fi-Phillips ionicity,A-constant,8467.5.This empirical correlation was used to calculate the hardness of 66 kinds of compounds. The calculated values of 36 kinds of them are in agreement with the experimental values.
1992, 9(2): 73-75
Abstract:
The nitric oxide complex of meso-tetra(p-nitrophenyl) porphinatoiron(Ⅱ)([T(p-NO2)PP] Fe(Ⅱ)(NO)) was prepared.The molecular structure of the complex was examined by means of UV-YIS, IR and EPR. The reaction of[T(p-NO2)PP]Fe(Ⅲ)Cl with NO and the effects of solvents on the absorption spectra of[T(p-NO2)PP]Fe(Ⅱ)(NO) were also studied.
The nitric oxide complex of meso-tetra(p-nitrophenyl) porphinatoiron(Ⅱ)([T(p-NO2)PP] Fe(Ⅱ)(NO)) was prepared.The molecular structure of the complex was examined by means of UV-YIS, IR and EPR. The reaction of[T(p-NO2)PP]Fe(Ⅲ)Cl with NO and the effects of solvents on the absorption spectra of[T(p-NO2)PP]Fe(Ⅱ)(NO) were also studied.
1992, 9(2): 76-78
Abstract:
A sensitive method for determination of gold in ore using cathodic stripping voltammetry is reported.The method is based on the adsorption of AuCl4- on the carbon paste surface at+1.4V (vs Ag/AgCl) in 0.1mol/L HCl solution.In the concentration range of 2~100ng/mL the stripping current and concentration of gold appeared a linear relationship. The detection limit is 0.2ng/mL after 5 min accumulation. The effects of different parameters on the response were examined.
A sensitive method for determination of gold in ore using cathodic stripping voltammetry is reported.The method is based on the adsorption of AuCl4- on the carbon paste surface at+1.4V (vs Ag/AgCl) in 0.1mol/L HCl solution.In the concentration range of 2~100ng/mL the stripping current and concentration of gold appeared a linear relationship. The detection limit is 0.2ng/mL after 5 min accumulation. The effects of different parameters on the response were examined.
1992, 9(2): 79-82
Abstract:
High molecular weight poly L-alanine(PL-ALa) was prepared by thermal ring-opening polymerization of L-alanine-N-carboxyl anhydride. The influence of solvent, reaction temperature and monomer concentration on the polymerzation rate and the molecular weight of PL-Ala has been studied. It was found that the rate of polymerization and the molecular weight of PL-Ala have a maximum value at about 70℃ in different reaction systems.
High molecular weight poly L-alanine(PL-ALa) was prepared by thermal ring-opening polymerization of L-alanine-N-carboxyl anhydride. The influence of solvent, reaction temperature and monomer concentration on the polymerzation rate and the molecular weight of PL-Ala has been studied. It was found that the rate of polymerization and the molecular weight of PL-Ala have a maximum value at about 70℃ in different reaction systems.
1992, 9(2): 83-85
Abstract:
Four mid-long chain a-chloroaliphatic acids(C8, C10,C12) were synthesized in 50~70% yield. Their physical and chemical constants, IR and1HNMR spectra data were determined. The method has a good specifity, without any α,α-dichloro-, β-and γ-chloro-acids as by products.
Four mid-long chain a-chloroaliphatic acids(C8, C10,C12) were synthesized in 50~70% yield. Their physical and chemical constants, IR and1HNMR spectra data were determined. The method has a good specifity, without any α,α-dichloro-, β-and γ-chloro-acids as by products.
1992, 9(2): 86-88
Abstract:
Molar magnetic susceptibilities Xm of EuP5O14 were determined from liquid nitrogen to room temperature by Faraday's method. Xm of EuP5O14 were also calculated from the energy levels of the multiplets of Eu3+ in EuP5O14 obtained from its spectral data. Both values were consistent with each other quite well.
Molar magnetic susceptibilities Xm of EuP5O14 were determined from liquid nitrogen to room temperature by Faraday's method. Xm of EuP5O14 were also calculated from the energy levels of the multiplets of Eu3+ in EuP5O14 obtained from its spectral data. Both values were consistent with each other quite well.
1992, 9(2): 89-95
Abstract:
Fourteen 1-(α-naphthylacetyl)-4-aroylthiosemicarbazidesⅡ and 3-(α-naphthylmethene)-4-aroyl-1,2,4-triazoline-5-thiones Ⅲ were prepared. The structures of typical compounis were confirmed by elemental analysis, IR,1HNMR and MS measurements. All the compounds Showed an antifungal activity against E.Coli.
Fourteen 1-(α-naphthylacetyl)-4-aroylthiosemicarbazidesⅡ and 3-(α-naphthylmethene)-4-aroyl-1,2,4-triazoline-5-thiones Ⅲ were prepared. The structures of typical compounis were confirmed by elemental analysis, IR,1HNMR and MS measurements. All the compounds Showed an antifungal activity against E.Coli.
1992, 9(2): 96-98
Abstract:
The Diels-Alder reaction of butadiene with maleic anhydride can bc catalyzed by various lanthanide chloride under mild conditions with satisfactory yield, The activities of the catalysts are greatly dependent on the atomical number of the lanthanide of the catalysts.
The Diels-Alder reaction of butadiene with maleic anhydride can bc catalyzed by various lanthanide chloride under mild conditions with satisfactory yield, The activities of the catalysts are greatly dependent on the atomical number of the lanthanide of the catalysts.
1992, 9(2): 99-101
Abstract:
The discharge and charge mechanisms of Zn/1 mol/L Zn(ClO4)2-PC/λ-MnO2 were investigated by microelectrode voltammetry, coulometry and XRD analysis. It is found that zinc can intercalate electrochemically into or deintercalate from λ-MnO2 in 1mol/L Zn(ClO)2-PC with the spinel structure of λ-MnO2 being remained intact.
The discharge and charge mechanisms of Zn/1 mol/L Zn(ClO4)2-PC/λ-MnO2 were investigated by microelectrode voltammetry, coulometry and XRD analysis. It is found that zinc can intercalate electrochemically into or deintercalate from λ-MnO2 in 1mol/L Zn(ClO)2-PC with the spinel structure of λ-MnO2 being remained intact.
1992, 9(2): 102-105
Abstract:
Copolymersd of diacetone acrylamide (DAAM)-styrene (St) and DAAM-methylmethacrylate (MMA) were used as pervaporation membrane materials for ethanol-water mixture separation.The results showed that a better permselectivity for water was obtained when the content of St or MMA in copolymers was high. And with increase of DAAM content in copolymer the permeation rate increased significantly.The pervaporation behavior is explained in terms of preferential sorption of water in copolymer membranes. Sorption plays an important role in all pervaporation process.
Copolymersd of diacetone acrylamide (DAAM)-styrene (St) and DAAM-methylmethacrylate (MMA) were used as pervaporation membrane materials for ethanol-water mixture separation.The results showed that a better permselectivity for water was obtained when the content of St or MMA in copolymers was high. And with increase of DAAM content in copolymer the permeation rate increased significantly.The pervaporation behavior is explained in terms of preferential sorption of water in copolymer membranes. Sorption plays an important role in all pervaporation process.
1992, 9(2): 106-110
Abstract:
Separation and determination of amino acids were carried out by means of a glycerolpropyl-diethylenesilyl bonded phase (GDSB) combined with a UV-detector at 254nm. An acetate buffer solution (pH 5.75) containing 2.5×10-4 mol/L of copper ion and 2.5×10-4 mol/L of hexyl sulfonate was used as a mobile phase. The effects of the mobile phase composition on capacity factor and detection sensitivity were examined. The results the suifability of GDSB system as a stationary phase for analysis of amino acids showed by HPLC.
Separation and determination of amino acids were carried out by means of a glycerolpropyl-diethylenesilyl bonded phase (GDSB) combined with a UV-detector at 254nm. An acetate buffer solution (pH 5.75) containing 2.5×10-4 mol/L of copper ion and 2.5×10-4 mol/L of hexyl sulfonate was used as a mobile phase. The effects of the mobile phase composition on capacity factor and detection sensitivity were examined. The results the suifability of GDSB system as a stationary phase for analysis of amino acids showed by HPLC.
1992, 9(2): 111-114
Abstract:
The dynamic mechanical properties of the segmented polyester polyurcthaneurea (PUU) elastomcrs based on 4,4'-diphenylmethane diisocyanate (MDI), ethylene diamine (ED) and polybutylene adipate (PBA) (mol. wt. of 1975 and 1228) have been studied. The results showed that PUU exhibited a two phase structure, and two major transitions corresponding to the soft and hard segments were observed. Several secondary relaxations were also observed. All the relaxations were affected by both the molecular weight of the soft segments and content of the hard segments. The degree of the phase segregation may be improved by increasing the hard segment content. There occured a multi-step rubbery platform in E~T curves. A model has been proposed for reasonable explanation for the existence of the multi-step platforms.
The dynamic mechanical properties of the segmented polyester polyurcthaneurea (PUU) elastomcrs based on 4,4'-diphenylmethane diisocyanate (MDI), ethylene diamine (ED) and polybutylene adipate (PBA) (mol. wt. of 1975 and 1228) have been studied. The results showed that PUU exhibited a two phase structure, and two major transitions corresponding to the soft and hard segments were observed. Several secondary relaxations were also observed. All the relaxations were affected by both the molecular weight of the soft segments and content of the hard segments. The degree of the phase segregation may be improved by increasing the hard segment content. There occured a multi-step rubbery platform in E~T curves. A model has been proposed for reasonable explanation for the existence of the multi-step platforms.
1992, 9(2): 115-118
Abstract:
The copolyethers of methoxy polyethylene glycol methacrylate (MEO16)with acrylamide derivatives, such as methylacrylamide (MA), N,N-dimethylacrylamide (DMA), and N,N-diethylacrylamide (DEA), were prepared by plasma-initiated polymerization. The order of conversion of the acrylamides is as follows:MA > DMA > DEA. The crystallinities(Xc) and the glass transition temperatures (Tg) of the copolyethers became lower after the addition of the acrylamides.The relations between the compsition of the P(MEO16-DMA) and the Xc, the Tg were discussed, The ionic conductivity of the P(MEO16-DMA)-LiClO4is 5.5×10-5S·cm-1 when the content of DMA is about 50mol% and the EO/Li is about 32 at 25℃, but that of the PMEO16-LiClO4 is 1.89×10-5S·cm-1 at the same conditions.
The copolyethers of methoxy polyethylene glycol methacrylate (MEO16)with acrylamide derivatives, such as methylacrylamide (MA), N,N-dimethylacrylamide (DMA), and N,N-diethylacrylamide (DEA), were prepared by plasma-initiated polymerization. The order of conversion of the acrylamides is as follows:MA > DMA > DEA. The crystallinities(Xc) and the glass transition temperatures (Tg) of the copolyethers became lower after the addition of the acrylamides.The relations between the compsition of the P(MEO16-DMA) and the Xc, the Tg were discussed, The ionic conductivity of the P(MEO16-DMA)-LiClO4is 5.5×10-5S·cm-1 when the content of DMA is about 50mol% and the EO/Li is about 32 at 25℃, but that of the PMEO16-LiClO4 is 1.89×10-5S·cm-1 at the same conditions.
1992, 9(2): 119-122
Abstract:
The hydroxycitronellal has been synthesized from citronellal. The oxazolidine derivative has been prepared from citroncllal and diethanolamine by using dehydrator for protecting citroncllal carbonyl. The citroncllal-dicthanolamine adduct were hydrated with the sulfuric acid and an affix catalytic promoter with subsequent hydrolysis to hydroxycitronellal.The optimum experimental conditions were obtained by using orthogonal experimental design. Thc yield of the condensation compound and the hydroxycitronellal have been achieved to be 96.6% and 87.7% respectively. The rate of inversion of the citronellal achieved 84.7%.
The hydroxycitronellal has been synthesized from citronellal. The oxazolidine derivative has been prepared from citroncllal and diethanolamine by using dehydrator for protecting citroncllal carbonyl. The citroncllal-dicthanolamine adduct were hydrated with the sulfuric acid and an affix catalytic promoter with subsequent hydrolysis to hydroxycitronellal.The optimum experimental conditions were obtained by using orthogonal experimental design. Thc yield of the condensation compound and the hydroxycitronellal have been achieved to be 96.6% and 87.7% respectively. The rate of inversion of the citronellal achieved 84.7%.
1992, 9(2): 123-126
Abstract:
The segregation and dissolution of M_n at the electrodes of hydrogen storage alloys, LaMmMnCoNi and AlMmMnCoNi (Mm-alloy of rare earth rich in lanthanum), have been studied in cycling course using XPS and electron probe techniques. It was observed that Mn inside the electrodes dispersed rapidly to the electrode surfaces in the active stage, forming MnO2. Both the capacities of the electrodes and the Mn content on the electrode surfaces gave maximum values in the cycling course, The segregation and dissolution of Mn in the hydrogen storage alloy electrode containing Al were slower than that in the alloy electrode without Al, The alloy electrode with and without Al in 80% discharge showed a cycling life of 520 and 350 times, respectively. It is concluded that Al may inhibit the segregation and dissolution of Mn and extend the cycling life of the eletrode.
The segregation and dissolution of M_n at the electrodes of hydrogen storage alloys, LaMmMnCoNi and AlMmMnCoNi (Mm-alloy of rare earth rich in lanthanum), have been studied in cycling course using XPS and electron probe techniques. It was observed that Mn inside the electrodes dispersed rapidly to the electrode surfaces in the active stage, forming MnO2. Both the capacities of the electrodes and the Mn content on the electrode surfaces gave maximum values in the cycling course, The segregation and dissolution of Mn in the hydrogen storage alloy electrode containing Al were slower than that in the alloy electrode without Al, The alloy electrode with and without Al in 80% discharge showed a cycling life of 520 and 350 times, respectively. It is concluded that Al may inhibit the segregation and dissolution of Mn and extend the cycling life of the eletrode.
