Login In
1984 Volume 1 Issue 1
1984, 1(1): 1-12
Abstract:
Photoacoustic spectroscopy (PAS) as a renewed spectroscopic techniquenow attracts in itself great interest and rapid development. In this paper a brief introdwction of the principle of PAS, varions fi-elds of its applications have been given with emphasis on the use of the tech-niqne as a new analytical tool in polymer chemistry and surface chemistrystudies.
Photoacoustic spectroscopy (PAS) as a renewed spectroscopic techniquenow attracts in itself great interest and rapid development. In this paper a brief introdwction of the principle of PAS, varions fi-elds of its applications have been given with emphasis on the use of the tech-niqne as a new analytical tool in polymer chemistry and surface chemistrystudies.
1984, 1(1): 13-20
Abstract:
This paper reports the use of benzilic acid [(C8H5)2 C(OH) COOH] crystals as the precipitant for scandium, instead of its sodium salt or am-monium solution. By adding the crystals to acidic solution of scandium andthen adjusting the acidity to pH 2.0-2.5, pure scandium benzilate can beobtained. This mode of precipitation prevents the formation of scandiumbasic salt and/or hydroxide. From the thermogravigram of the precipitateso obtained, it has been shown that precipitates dried at 160° and 140℃ cor-respond to Sc[(C6H5)2C(OH)COO]3 and its monohydrate respectively. From 592℃ upward, the precipitate becomes scandium oxide. To ensure completeconversion, 650℃ should be used for ignition. Quantitative precipitation ofscandium benzilate can be achieved from solutions of pH 2.0-5.0.BeyondpH5, the precipitate hydrolyzes to basic salt. The amount of benzilicacid needed for quantitative precipitation is 1.5 to 5 fold of the theoretical value. The interference of iron(Ⅲ) can be avoided by (a) reducing to ferrousstate with ascorbic acid, or(b) masking with citric acid--triethanolaminemixture. The latter masks aluminum (Ⅲ) too. Hydrogen peroxide maskingeliminates the interference of titanium(Ⅳ). Yttrium(Ⅲ), larithanum (Ⅲ)and cerium (Ⅲ) benzilates begin to precipitate at pH 1.3, 3.1 and 2.6,respectively. Therefore it is impossible to determine scandium in theirpresence, unless separation is carried out beforehand.
This paper reports the use of benzilic acid [(C8H5)2 C(OH) COOH] crystals as the precipitant for scandium, instead of its sodium salt or am-monium solution. By adding the crystals to acidic solution of scandium andthen adjusting the acidity to pH 2.0-2.5, pure scandium benzilate can beobtained. This mode of precipitation prevents the formation of scandiumbasic salt and/or hydroxide. From the thermogravigram of the precipitateso obtained, it has been shown that precipitates dried at 160° and 140℃ cor-respond to Sc[(C6H5)2C(OH)COO]3 and its monohydrate respectively. From 592℃ upward, the precipitate becomes scandium oxide. To ensure completeconversion, 650℃ should be used for ignition. Quantitative precipitation ofscandium benzilate can be achieved from solutions of pH 2.0-5.0.BeyondpH5, the precipitate hydrolyzes to basic salt. The amount of benzilicacid needed for quantitative precipitation is 1.5 to 5 fold of the theoretical value. The interference of iron(Ⅲ) can be avoided by (a) reducing to ferrousstate with ascorbic acid, or(b) masking with citric acid--triethanolaminemixture. The latter masks aluminum (Ⅲ) too. Hydrogen peroxide maskingeliminates the interference of titanium(Ⅳ). Yttrium(Ⅲ), larithanum (Ⅲ)and cerium (Ⅲ) benzilates begin to precipitate at pH 1.3, 3.1 and 2.6,respectively. Therefore it is impossible to determine scandium in theirpresence, unless separation is carried out beforehand.
1984, 1(1): 21-26
Abstract:
The electric conductivities of molten KCl-NaCl (1: 1mol)-RECl3 were measured by the A.C.bridge method. The following empirical expression of the specific conductivity κ of the melt was obtained as a function of tem-perature: κ=A+B(t-700) where t is temperature (from 700℃ to 850℃), A and B are constant given in the paper. The deviation of the obtained values from the calculated (for the concentration of rare earth chlorides 10-50wt%) was discussed in view of the possible formation of a complex.
The electric conductivities of molten KCl-NaCl (1: 1mol)-RECl3 were measured by the A.C.bridge method. The following empirical expression of the specific conductivity κ of the melt was obtained as a function of tem-perature: κ=A+B(t-700) where t is temperature (from 700℃ to 850℃), A and B are constant given in the paper. The deviation of the obtained values from the calculated (for the concentration of rare earth chlorides 10-50wt%) was discussed in view of the possible formation of a complex.
1984, 1(1): 27-31
Abstract:
In this paper a simple, sensitive method for the determination of eu-ropium in samarium and gadolinium oxides using a graphite tube lined with tantalum foil is described. The effects of hydrochloric acid concentration and samarium and gadolinium matrix are discussed.The method can be used directly for the sample analysis without predissociation of matrix.
In this paper a simple, sensitive method for the determination of eu-ropium in samarium and gadolinium oxides using a graphite tube lined with tantalum foil is described. The effects of hydrochloric acid concentration and samarium and gadolinium matrix are discussed.The method can be used directly for the sample analysis without predissociation of matrix.
1984, 1(1): 32-35
Abstract:
In this paper the determination of the degree of association of polybu-tadienyl lithium in toluene as solvent has been reported. The experimental results show that the average degree of association of polybutadienyl lithiumin toluene is equal or greater than 2 (when the initiator concentratonis>1×10-3mol/l). The viscosity ratio is not found to be influenced by the variation of shear velocity in viscolsimeter, when the degree of association of polybutadienyl lithium is measured by viscosimetry.
In this paper the determination of the degree of association of polybu-tadienyl lithium in toluene as solvent has been reported. The experimental results show that the average degree of association of polybutadienyl lithiumin toluene is equal or greater than 2 (when the initiator concentratonis>1×10-3mol/l). The viscosity ratio is not found to be influenced by the variation of shear velocity in viscolsimeter, when the degree of association of polybutadienyl lithium is measured by viscosimetry.
1984, 1(1): 36-41
Abstract:
Electroreduction of eriochrome blue black B was studied by d.c. pola-rography, differential pulse polarography and cyclic voltammetry. Only a single wave which was diffusion-controlled and totally irreversible appeared over the range of pH2-12. With increasing pH, the electron number(according to logarithmic analysis) of the electrode reaction was changed from 2 to 4 around pH6, and the E1/2 shifted linearly toward more nega-tive potential with a slope of-65mV/pH. Based on the experimental results, a mechanism involving the disproportionation of an unstable inter-mediate was proposed for the reducton of eriochrome blue black B, and by this, the change of electron number with pH was explained.
Electroreduction of eriochrome blue black B was studied by d.c. pola-rography, differential pulse polarography and cyclic voltammetry. Only a single wave which was diffusion-controlled and totally irreversible appeared over the range of pH2-12. With increasing pH, the electron number(according to logarithmic analysis) of the electrode reaction was changed from 2 to 4 around pH6, and the E1/2 shifted linearly toward more nega-tive potential with a slope of-65mV/pH. Based on the experimental results, a mechanism involving the disproportionation of an unstable inter-mediate was proposed for the reducton of eriochrome blue black B, and by this, the change of electron number with pH was explained.
1984, 1(1): 42-47
Abstract:
In this work trace tellurium has been determined by the anodic strip-ping voltammetry on a gold plated electrode or on a gold film deposited ona glassy graphite electrode. Sensitivity, accuracy of the method, recoveryratio as well as the influence of the interfering coexistent elements are disc-ussed.The sample was previously separated and adsorbed through sulfhydrylcotton fiber. In O.1M perchloric acid medium the amount of tellurium inthe water of Min River and in East Sea have been determined to be 8.1and 1.8 ng/1, respectively,with the recovery error less than 10%.
In this work trace tellurium has been determined by the anodic strip-ping voltammetry on a gold plated electrode or on a gold film deposited ona glassy graphite electrode. Sensitivity, accuracy of the method, recoveryratio as well as the influence of the interfering coexistent elements are disc-ussed.The sample was previously separated and adsorbed through sulfhydrylcotton fiber. In O.1M perchloric acid medium the amount of tellurium inthe water of Min River and in East Sea have been determined to be 8.1and 1.8 ng/1, respectively,with the recovery error less than 10%.
1984, 1(1): 48-55
Abstract:
The FTIR spectra of fourteen rare earth tris (4,4,4-trifluoro-1-(2-thie-nyl)-1, 3-butanedione) dihydrates in the 100-4000 cm-1 range have been studied and the assignment of peaks in the far and middle infrared region has been discussed. Six RE-O absorption bands were observed, two of which are in the mid-infrared region, namely 489-508 cm-1 for the asym-metrical stretch and 456-475-1cm for the symmetrical stretch. Four bands are in the far infrared region, three of them are assigned to the metal-che-late oxygen bonds, while the fourth band results from the coordination with the water molecule. The frequencies of the bands near 456-489-1cm change periodically with atomic number, showing the "tetrad effect", which is characteristic of lanthanides. The absorption peak due to the carbonyl group and that due to the C=C bond are lowered by about 60cm-1 respectively in comparison with the free HTTA. This is an evidence of conjugation inthe metal chelate rings.
The FTIR spectra of fourteen rare earth tris (4,4,4-trifluoro-1-(2-thie-nyl)-1, 3-butanedione) dihydrates in the 100-4000 cm-1 range have been studied and the assignment of peaks in the far and middle infrared region has been discussed. Six RE-O absorption bands were observed, two of which are in the mid-infrared region, namely 489-508 cm-1 for the asym-metrical stretch and 456-475-1cm for the symmetrical stretch. Four bands are in the far infrared region, three of them are assigned to the metal-che-late oxygen bonds, while the fourth band results from the coordination with the water molecule. The frequencies of the bands near 456-489-1cm change periodically with atomic number, showing the "tetrad effect", which is characteristic of lanthanides. The absorption peak due to the carbonyl group and that due to the C=C bond are lowered by about 60cm-1 respectively in comparison with the free HTTA. This is an evidence of conjugation inthe metal chelate rings.
1984, 1(1): 56-62
Abstract:
The IR spectra of pyridine adsorbed on oxidic and sulfided form of Ni-Mo and Co-Mo catalyst systems were measured. The results showed that the OH group played an important role in the dispersion of MoO3 on thesurface of support and that Ni and Co promotors apparently increased thedispersion of MoO3 on the support. Kinetic results and the TGA and IRspectra indicated that a certain site of Lewis type,not of Brosted,may playan important role in the HDN reaction of quinoline.
The IR spectra of pyridine adsorbed on oxidic and sulfided form of Ni-Mo and Co-Mo catalyst systems were measured. The results showed that the OH group played an important role in the dispersion of MoO3 on thesurface of support and that Ni and Co promotors apparently increased thedispersion of MoO3 on the support. Kinetic results and the TGA and IRspectra indicated that a certain site of Lewis type,not of Brosted,may playan important role in the HDN reaction of quinoline.
1984, 1(1): 63-68
Abstract:
In this paper, in contrast to the conventional practice of measuring porphyrins with side chain carboxylic groups in the form of their esters in CDCl3 solutions,the proton and carbon-13 NMR spectra of hematoporphyrin.protoporphyrin and porphyrin c in acidic solvents are presented. This app-roach facilitates the structural identification and production monitoring of these medical porphyrins.
In this paper, in contrast to the conventional practice of measuring porphyrins with side chain carboxylic groups in the form of their esters in CDCl3 solutions,the proton and carbon-13 NMR spectra of hematoporphyrin.protoporphyrin and porphyrin c in acidic solvents are presented. This app-roach facilitates the structural identification and production monitoring of these medical porphyrins.
1984, 1(1): 69-73
Abstract:
The free radicals trapped in both polyamide (PA 1010(Ⅰ)) and polya-mide 1010 in presence of maleimides (PA 1010(Ⅱ)) under irradiation with 60Co γ-rays in vacuum and at room temperature were studied by ESR spe-ctroscopy.The decay of the ESR spectrum of the trapped radicals in PA1010(Ⅰ) and PA1010(Ⅱ) has been measured in the course of heat-treatment.It has been observed that the decay follows a second-order rate law and is closely related to the postcrosslinking of irradiated PA 1010(Ⅰ) and PA1010(Ⅱ) under heat-treatment.
The free radicals trapped in both polyamide (PA 1010(Ⅰ)) and polya-mide 1010 in presence of maleimides (PA 1010(Ⅱ)) under irradiation with 60Co γ-rays in vacuum and at room temperature were studied by ESR spe-ctroscopy.The decay of the ESR spectrum of the trapped radicals in PA1010(Ⅰ) and PA1010(Ⅱ) has been measured in the course of heat-treatment.It has been observed that the decay follows a second-order rate law and is closely related to the postcrosslinking of irradiated PA 1010(Ⅰ) and PA1010(Ⅱ) under heat-treatment.
1984, 1(1): 74-80
Abstract:
Factors governing the microstructure of 1, 2-polybutadienes prepared with molybdenum catalysts have been stedied. It was found that the vinyl content of the 1,2-polybutadienes could be regulated by addition cf allyl halide and the order of addition of the catalyst components as well as the polymerization temperature. Allyl bromide appeared more effective for the regulation of 1,2-stereoisomer and the sequence distribution as. well.
Factors governing the microstructure of 1, 2-polybutadienes prepared with molybdenum catalysts have been stedied. It was found that the vinyl content of the 1,2-polybutadienes could be regulated by addition cf allyl halide and the order of addition of the catalyst components as well as the polymerization temperature. Allyl bromide appeared more effective for the regulation of 1,2-stereoisomer and the sequence distribution as. well.
1984, 1(1): 81-86
Abstract:
Two kinds of doped YAG crystals of thirteen groups being grown by Czochralski method have been analyzed. It has been proved that the compo-sition of the doped crystals is definitely rich-in rare earths and is indepen-dent of the composition of the melting matrix, the condition of crystal growth and the atmosphere of the furnace.In this paper we have firstly deter mined the formula of YAG crystal and the variance in its composition.
Two kinds of doped YAG crystals of thirteen groups being grown by Czochralski method have been analyzed. It has been proved that the compo-sition of the doped crystals is definitely rich-in rare earths and is indepen-dent of the composition of the melting matrix, the condition of crystal growth and the atmosphere of the furnace.In this paper we have firstly deter mined the formula of YAG crystal and the variance in its composition.
1984, 1(1): 87-94
Abstract:
The contionuous and intermittent chemical stress relaxations of γ-irra-diated cross-linked low density polyethylene containing different amount of antioxidant D were studied. It was discovered that the cleavage occurs randomly along the network chains. The relaxation may be divided mainly into the oxidation induction and oxidation breaking stages. The activation energy of chemical stress relaxation was found to be 30 Kcal/mole, which is independent of D content and radiation dose. By intermittent relaxation, it was shown that the β-value, the fraction of chains being reformed after scission is increasing with the increase of relaxation temperature and D content.
The contionuous and intermittent chemical stress relaxations of γ-irra-diated cross-linked low density polyethylene containing different amount of antioxidant D were studied. It was discovered that the cleavage occurs randomly along the network chains. The relaxation may be divided mainly into the oxidation induction and oxidation breaking stages. The activation energy of chemical stress relaxation was found to be 30 Kcal/mole, which is independent of D content and radiation dose. By intermittent relaxation, it was shown that the β-value, the fraction of chains being reformed after scission is increasing with the increase of relaxation temperature and D content.
1984, 1(1): 95-97
Abstract:
1984, 1(1): 98-102
Abstract:
