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1987 Volume 4 Issue 3
1987, 4(3): 1-10
Abstract:
In this paper a new technique for polymer synthesis known as group transfer polymerization is reviewed. The process is used for polymerization of a, β unsaturated carbonyl compounds with active silyl compound as initiator in the presence of catalyst. GTP provides "living polymer" with narrow molecular weight distribution which is useful for preparation of block copolymers and telechelic polymers. The application and recent progress of the method have also been described.
In this paper a new technique for polymer synthesis known as group transfer polymerization is reviewed. The process is used for polymerization of a, β unsaturated carbonyl compounds with active silyl compound as initiator in the presence of catalyst. GTP provides "living polymer" with narrow molecular weight distribution which is useful for preparation of block copolymers and telechelic polymers. The application and recent progress of the method have also been described.
1987, 4(3): 11-16
Abstract:
Random ethylene-propylene copolymers with statistically distributed long C3-sequences should have thermoplastic elastomeric properties as a result of the dual features in its molecular structure, contributing both to elasticity and PP higher temperature plasticity. In this work 6-TiCl3-Et2AlCl catalyst was used in an attempt to obtain E-P copolymers with isotactic PP sequences for the benefit of higher strength.The effect was studied of[Ti],[Al]/[Ti], polymerization temperature and duration, and monomer composition on the polymerization yield,[η], MWD and copolymer composition. Structure of the copolymers was proved by heptane-extraction, dynamic mechanical properties,IR spectra and x-ray diffraction studies. Crystallinity is the prime factor responsible for their strength, to which[η] also contribates. High C3 E-P copolymers are characterized by high crystallinity, strength and hardness and high elongation. A sample with C3=79.8 mol% had a 300% modulus of 102 kg/cm2 and a breaking strength of 135 kg/cm2.
Random ethylene-propylene copolymers with statistically distributed long C3-sequences should have thermoplastic elastomeric properties as a result of the dual features in its molecular structure, contributing both to elasticity and PP higher temperature plasticity. In this work 6-TiCl3-Et2AlCl catalyst was used in an attempt to obtain E-P copolymers with isotactic PP sequences for the benefit of higher strength.The effect was studied of[Ti],[Al]/[Ti], polymerization temperature and duration, and monomer composition on the polymerization yield,[η], MWD and copolymer composition. Structure of the copolymers was proved by heptane-extraction, dynamic mechanical properties,IR spectra and x-ray diffraction studies. Crystallinity is the prime factor responsible for their strength, to which[η] also contribates. High C3 E-P copolymers are characterized by high crystallinity, strength and hardness and high elongation. A sample with C3=79.8 mol% had a 300% modulus of 102 kg/cm2 and a breaking strength of 135 kg/cm2.
1987, 4(3): 17-21
Abstract:
This paper discusses the exchange reaction between WCl6 and four alcohols:n-C4H9OH, n-C5H11)OH, t-C7H15OH and n-C10H21OH. The results show that the products of the reaction may be represented as WCl4(OR)2, The content of 1,2-unit in polymer prepared with WCl4(OR)2-Al(i-Bu)3 catalyst in hydrogenated gasoline is found to be about 80% and the catalyst system with R=n-C10H21O gives the highest activity. The molecular weight distribution is independent of the polymerization conditions used.
This paper discusses the exchange reaction between WCl6 and four alcohols:n-C4H9OH, n-C5H11)OH, t-C7H15OH and n-C10H21OH. The results show that the products of the reaction may be represented as WCl4(OR)2, The content of 1,2-unit in polymer prepared with WCl4(OR)2-Al(i-Bu)3 catalyst in hydrogenated gasoline is found to be about 80% and the catalyst system with R=n-C10H21O gives the highest activity. The molecular weight distribution is independent of the polymerization conditions used.
1987, 4(3): 22-25
Abstract:
An IPN from polyurethane of hydroxy terminated poly (butadiene-acrylonitrile) (HTBN) prepolymer and poly(methyl acrylate) was synthesized by simultaneous crosslinking polymerization. The relationship between the mechanical properties of IPNs and the ratio of components and NCO contents in polyursthane networks has been studied through the measurement of tensile strength, shear strength and TG analyses. The results showed that the IPN has better mechanical and thermal properties than the homopolymers from corresponding monomers. When PU/PMA=8/2, the mechanical property of IPNs showed a maximum value due to the synergy effect.
An IPN from polyurethane of hydroxy terminated poly (butadiene-acrylonitrile) (HTBN) prepolymer and poly(methyl acrylate) was synthesized by simultaneous crosslinking polymerization. The relationship between the mechanical properties of IPNs and the ratio of components and NCO contents in polyursthane networks has been studied through the measurement of tensile strength, shear strength and TG analyses. The results showed that the IPN has better mechanical and thermal properties than the homopolymers from corresponding monomers. When PU/PMA=8/2, the mechanical property of IPNs showed a maximum value due to the synergy effect.
1987, 4(3): 26-30
Abstract:
The photopolarization and wavelength response of single crystal CdS electrode in polysulfide and cyanide couple were measured. The conversion efficiency, fill factor and band gap were then calculated. Impedance spectra were also measured using a frequency response analyzer at various frequencies. The complex plane diagrams obtained were approximately equal to a semicircle, therefore,the interfacial structure can be described with asimple model. The Mott-Schottky plots show a good linearity. By extrapolating these straight lines to the potential axis the flat-band potentials were obtained which were quantitatively in agreement with potentials of photocurrent transition in photopolarization curves. A linear relationship was found between the flat-band potential of CdS electrode and the pH value of the redox couple. This relationship is explained in ferms of the formation of hydrated oxide film on the surface of CdS electrode in equilibrium with the Haq+ ions in solution.
The photopolarization and wavelength response of single crystal CdS electrode in polysulfide and cyanide couple were measured. The conversion efficiency, fill factor and band gap were then calculated. Impedance spectra were also measured using a frequency response analyzer at various frequencies. The complex plane diagrams obtained were approximately equal to a semicircle, therefore,the interfacial structure can be described with asimple model. The Mott-Schottky plots show a good linearity. By extrapolating these straight lines to the potential axis the flat-band potentials were obtained which were quantitatively in agreement with potentials of photocurrent transition in photopolarization curves. A linear relationship was found between the flat-band potential of CdS electrode and the pH value of the redox couple. This relationship is explained in ferms of the formation of hydrated oxide film on the surface of CdS electrode in equilibrium with the Haq+ ions in solution.
1987, 4(3): 31-34
Abstract:
The critical micelle concentration (CMC) of three kinds of polyoxyethylene-polyoxypro-pylene block copolymer-L64, AE21, AP221 has been measured by surface tension and benzopurpurine uptake. Results showed that L64 and AE21 form monomolecular micelles at low concentration and aggregated micelles at high concentration, while AP221 only form saggregated micelle at low concentration. Measurement of CMC at different temperature showed that in aqueous solution temperature has little effect on the CMC of L64 for monomolecular micellization, but has marked effect for aggregated micellization which decreases sharply with increase of temperature. Heat of formation of aggregated micelle has a large value, of 140.6kJ/mol.
The critical micelle concentration (CMC) of three kinds of polyoxyethylene-polyoxypro-pylene block copolymer-L64, AE21, AP221 has been measured by surface tension and benzopurpurine uptake. Results showed that L64 and AE21 form monomolecular micelles at low concentration and aggregated micelles at high concentration, while AP221 only form saggregated micelle at low concentration. Measurement of CMC at different temperature showed that in aqueous solution temperature has little effect on the CMC of L64 for monomolecular micellization, but has marked effect for aggregated micellization which decreases sharply with increase of temperature. Heat of formation of aggregated micelle has a large value, of 140.6kJ/mol.
1987, 4(3): 35-38
Abstract:
The luminescence of Ce3+ in LnOX was studied by excitation and emission spectroscopy. The LnOX studied belong to the same structure type, tetragonal, with space group D4h7-P4/nmm, site symmetry of Ln3+ C4v. The spectra show that when X is kept identical but with different Ln the spectra only manifest minor differences:whereas with different X there are rather noticeable changes in spectra, the corresponding peaks in the spectra shift to lower energy in the order of Cl-Br-I. Some differences were observed in the behavior of La compound in comparing with that of Gd or Y compounds, especially in the excitation spectra. It was discussed in terms of the differences bstween ionic radius of Ce3+ and those of the host cations.
The luminescence of Ce3+ in LnOX was studied by excitation and emission spectroscopy. The LnOX studied belong to the same structure type, tetragonal, with space group D4h7-P4/nmm, site symmetry of Ln3+ C4v. The spectra show that when X is kept identical but with different Ln the spectra only manifest minor differences:whereas with different X there are rather noticeable changes in spectra, the corresponding peaks in the spectra shift to lower energy in the order of Cl-Br-I. Some differences were observed in the behavior of La compound in comparing with that of Gd or Y compounds, especially in the excitation spectra. It was discussed in terms of the differences bstween ionic radius of Ce3+ and those of the host cations.
1987, 4(3): 39-42
Abstract:
Using SnO2-ZrO2 and SnO2-ThO2 systems as the gas sensitive materials, we have investigated the effects of sintering temperature on the structure and particle size as well as on the sensitivities and selectivities of the material. The experimental results show that the sintering temperature not only effects on the sensitivity of gas sensitive materials but also strongly on their selectivity under the experimental conditions.The sensitivity of the material does not always decrease as sintering temperature increases,it sometimes gives a maximum value at certain temperature of sintering and for SnO2-ZrO2 system its selectivity loses when sintering temperature is elevated up to 800℃.
Using SnO2-ZrO2 and SnO2-ThO2 systems as the gas sensitive materials, we have investigated the effects of sintering temperature on the structure and particle size as well as on the sensitivities and selectivities of the material. The experimental results show that the sintering temperature not only effects on the sensitivity of gas sensitive materials but also strongly on their selectivity under the experimental conditions.The sensitivity of the material does not always decrease as sintering temperature increases,it sometimes gives a maximum value at certain temperature of sintering and for SnO2-ZrO2 system its selectivity loses when sintering temperature is elevated up to 800℃.
1987, 4(3): 43-48
Abstract:
The structure and components of A-stage benzoguanamine-formaldehyde resins obtained in the conditions of various feed ratios and reaction times are identified by chemical analysis of formaldehyde contents in the resins, determination of Mn with VPO, and assignment of H-NMR spectra. It is proved that the resins are a series of methylol derivatives of benzoguanamine. The molecular species in the resins are datermined quantitatively with high-speed liquid chromatographic technique.
The structure and components of A-stage benzoguanamine-formaldehyde resins obtained in the conditions of various feed ratios and reaction times are identified by chemical analysis of formaldehyde contents in the resins, determination of Mn with VPO, and assignment of H-NMR spectra. It is proved that the resins are a series of methylol derivatives of benzoguanamine. The molecular species in the resins are datermined quantitatively with high-speed liquid chromatographic technique.
1987, 4(3): 49-52
Abstract:
17 indolinospirobenzopyran compounds were synthesized through the reaction of TTOI with salicylic aldehyde derivatives, 8 of them have not been reported in literature. In study the compounds were devided into two groups:A-compounds without nitrogroup and B-compounds which have NO2 in molecule. The results showed that compounds of group A in general can not be purified from its alcoholic solution, while compounds of group B are easily precipited from alcohol solution with metal lustre and show a better photochromic property. A number of polymers have been tested for coatings for compounds of group B, all of them were bad in photochromism, except polyvinyl butyral.
17 indolinospirobenzopyran compounds were synthesized through the reaction of TTOI with salicylic aldehyde derivatives, 8 of them have not been reported in literature. In study the compounds were devided into two groups:A-compounds without nitrogroup and B-compounds which have NO2 in molecule. The results showed that compounds of group A in general can not be purified from its alcoholic solution, while compounds of group B are easily precipited from alcohol solution with metal lustre and show a better photochromic property. A number of polymers have been tested for coatings for compounds of group B, all of them were bad in photochromism, except polyvinyl butyral.
1987, 4(3): 53-55
Abstract:
The glass transition temperature and the tensile strength of poly (butadiene-co-acrylonitrile) filled with graphite powder, molybdenum disulfide powder and silica were measured. The results showed that the copolymer filled with graphite has the highest tensile strength and percentage of bound rubber as compared with the copolymers containing either of the other two fillers. Tg (U) of the copolymer was verified.
The glass transition temperature and the tensile strength of poly (butadiene-co-acrylonitrile) filled with graphite powder, molybdenum disulfide powder and silica were measured. The results showed that the copolymer filled with graphite has the highest tensile strength and percentage of bound rubber as compared with the copolymers containing either of the other two fillers. Tg (U) of the copolymer was verified.
SYNTHESIS,STRUCTURE AND PROPERTIS OF COPOLYMER OF CHOLESTERIC METHACRYLIC ESTER Ⅰ.SYNTHESIS OF PCHPM
1987, 4(3): 56-57
Abstract:
By reacting 2, 4-di-isocyanatotoluene with cholesterol and 1, 2-hydroxypropyl methacrylate, a new monomer containing cholesteric group was prepared. The monomer was then copolymerized with 1,2-hydroxypropyl methacrylate in different proportions. Copolymers with cholesteric ester side chain from 1,2-hydroxypropyl 2,4-diisocyanatotoluene methacrylate were prepared.The formation of monomer and copolymer has been identified by IR and NMR spectroscopic methods.
By reacting 2, 4-di-isocyanatotoluene with cholesterol and 1, 2-hydroxypropyl methacrylate, a new monomer containing cholesteric group was prepared. The monomer was then copolymerized with 1,2-hydroxypropyl methacrylate in different proportions. Copolymers with cholesteric ester side chain from 1,2-hydroxypropyl 2,4-diisocyanatotoluene methacrylate were prepared.The formation of monomer and copolymer has been identified by IR and NMR spectroscopic methods.
1987, 4(3): 58-59
Abstract:
Radiation graft copolymer of polystyrene-g-acrylic acid has been characterized by XPS. It is found that along with the main peak C1S there is a photoelectron peak at 289.0eV that appears to be C1S of-???19870317???-OH group and shows the presence of polyacrylic acid grafted on the polystyrene. The graft level obtained by XPS method is consistent with that from gravimetric method., Radiation graft copolymer of polystyrene-g-acrylic acid has been characterized by XPS. It is found that along with the main peak C1S there is a photoelectron peak at 289.0eV that appears to be C1S of-
-OH group and shows the presence of polyacrylic acid grafted on the polystyrene. The graft level obtained by XPS method is consistent with that from gravimetric method.
Radiation graft copolymer of polystyrene-g-acrylic acid has been characterized by XPS. It is found that along with the main peak C1S there is a photoelectron peak at 289.0eV that appears to be C1S of-???19870317???-OH group and shows the presence of polyacrylic acid grafted on the polystyrene. The graft level obtained by XPS method is consistent with that from gravimetric method., Radiation graft copolymer of polystyrene-g-acrylic acid has been characterized by XPS. It is found that along with the main peak C1S there is a photoelectron peak at 289.0eV that appears to be C1S of-
-OH group and shows the presence of polyacrylic acid grafted on the polystyrene. The graft level obtained by XPS method is consistent with that from gravimetric method.
1987, 4(3): 60-63
Abstract:
In comparison of the 1H NMR spectra of the long-oil alkyd resins,saturated fatty acid, oleic acid, and soybean oil and the 13C NMR spectra of the alkyd resins, it deduced that the valuable qualitative and quantitative information of alkyd resins can be obtained by using NMR technique
In comparison of the 1H NMR spectra of the long-oil alkyd resins,saturated fatty acid, oleic acid, and soybean oil and the 13C NMR spectra of the alkyd resins, it deduced that the valuable qualitative and quantitative information of alkyd resins can be obtained by using NMR technique
1987, 4(3): 64-66
Abstract:
A sensitive method for trace determination of beryllium is developed. In a buffer solution of pH5.5 of (CH2)6N4-HCl and in the presence of emulsifier OP and sodium dodecyl-benzene sulfonate (SDBS) Be(Ⅱ) forms a purple complex with chromazurol B(CAB). The molar absorptivity coefficient of the complex is 8.55×104 (605-610nm). Beer's law is obeyed with concentration of beryllium ranging from O to 2.5μg/25ml. The composition of the complex was estimated as Be(Ⅱ):CAB=1:2. The method has been applied sactisfactority to the determination of Be in minerals.
A sensitive method for trace determination of beryllium is developed. In a buffer solution of pH5.5 of (CH2)6N4-HCl and in the presence of emulsifier OP and sodium dodecyl-benzene sulfonate (SDBS) Be(Ⅱ) forms a purple complex with chromazurol B(CAB). The molar absorptivity coefficient of the complex is 8.55×104 (605-610nm). Beer's law is obeyed with concentration of beryllium ranging from O to 2.5μg/25ml. The composition of the complex was estimated as Be(Ⅱ):CAB=1:2. The method has been applied sactisfactority to the determination of Be in minerals.
1987, 4(3): 67-69
Abstract:
In this paper the DTA spectra for 15 kinds of dimethylsulphoxide complexes of rare earth nitrates have been reeorded. The results were interpreted in terms of the difference in ion radia, symmetry of space groups and stereohindrance.
In this paper the DTA spectra for 15 kinds of dimethylsulphoxide complexes of rare earth nitrates have been reeorded. The results were interpreted in terms of the difference in ion radia, symmetry of space groups and stereohindrance.
1987, 4(3): 70-72
Abstract:
The miero-struetures of the fraetions and the gel of Ni-catalysde poly butadiene Were studied by FTIR. It was shown that the lower moteeular weight fraction has higher trans-1,4 and vinyl-1,2 contents and the that with higher moleeular weight has higher cis-1,4 content,indieating that more trans-1,4 or vinyl units are formed at the earlier perind of the chain propagation. The trans-1,4 and vinyl-1,2 contents in the gel are more than those in the sol of the same sampla. It is deduced that there is more structural similarity between the gel and the lower moleeular weight fraetions.
The miero-struetures of the fraetions and the gel of Ni-catalysde poly butadiene Were studied by FTIR. It was shown that the lower moteeular weight fraction has higher trans-1,4 and vinyl-1,2 contents and the that with higher moleeular weight has higher cis-1,4 content,indieating that more trans-1,4 or vinyl units are formed at the earlier perind of the chain propagation. The trans-1,4 and vinyl-1,2 contents in the gel are more than those in the sol of the same sampla. It is deduced that there is more structural similarity between the gel and the lower moleeular weight fraetions.
1987, 4(3): 73-75
Abstract:
The character of cerium oxide membrane ion-selective electrode (ISE) for individual and mixed rare earth system in the non-linear response region has been investigated. The potential of the linear response region of ISE for HCl-CeCl3 system at pH=4.9-6.0 and rare earth conceniration (C)=10-2-10-5M can be described as:E=-30 lgCCeCl-47.1 The relations of △E-C and △E-pH for HCl-PrCl3 system show that when pH<2 the interference is higher and the electrode can't be used for the measurement. The relations of △E-C for two rare earths mixed (Pr-Nd)Cl3 C=0.25-0.7M, four rare earths (La-Ce-Pr-Nd) Cl3 C=0.14-0.7M and fifteen rare earths (La-Lu) and Y C=0.2-1.0M systems in the presence of NH4Cl show that when pH ≥ 2 the responses similar to those what in the individual rare earth, while pH<2 the interference of the acidity is evident. A general, more accurate model for various systems is proposed through mathmatical simulation:E=B1 lg[Ci+B2(Ci+Cj)B3]
The character of cerium oxide membrane ion-selective electrode (ISE) for individual and mixed rare earth system in the non-linear response region has been investigated. The potential of the linear response region of ISE for HCl-CeCl3 system at pH=4.9-6.0 and rare earth conceniration (C)=10-2-10-5M can be described as:E=-30 lgCCeCl-47.1 The relations of △E-C and △E-pH for HCl-PrCl3 system show that when pH<2 the interference is higher and the electrode can't be used for the measurement. The relations of △E-C for two rare earths mixed (Pr-Nd)Cl3 C=0.25-0.7M, four rare earths (La-Ce-Pr-Nd) Cl3 C=0.14-0.7M and fifteen rare earths (La-Lu) and Y C=0.2-1.0M systems in the presence of NH4Cl show that when pH ≥ 2 the responses similar to those what in the individual rare earth, while pH<2 the interference of the acidity is evident. A general, more accurate model for various systems is proposed through mathmatical simulation:E=B1 lg[Ci+B2(Ci+Cj)B3]
1987, 4(3): 76-77
Abstract:
A new type of PVC membrane ISE of pyridine as well as of N, N-dimethylaniline was prepared by using chromium trioxide-pyridine complex as active material. The potential Nernst responses for pyridinium and N, N-dimathylanilinium ions ranged in 1×10-1-1×10-5 M and 1×10-1-6.3×10-6M respectively. Pyridinium chlorochromate C5H5NHCrO3Cl can also be used as active material and its potential Nernst response range was found to be the same as chromium trioxide-pyridine complex.
A new type of PVC membrane ISE of pyridine as well as of N, N-dimethylaniline was prepared by using chromium trioxide-pyridine complex as active material. The potential Nernst responses for pyridinium and N, N-dimathylanilinium ions ranged in 1×10-1-1×10-5 M and 1×10-1-6.3×10-6M respectively. Pyridinium chlorochromate C5H5NHCrO3Cl can also be used as active material and its potential Nernst response range was found to be the same as chromium trioxide-pyridine complex.
