The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results ...The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results show thatthe polymer mixtures are compatible in DMF solution in the absence of urea. The influence of urea addition on the degree ofcompatibility of the polymer mixtures has been studied in terms of the compatibility parameters (△b_m and △[η]_m). It wasfound that the compatibility of the polymer mixtures is decreased with increasing urea addition, passing through a minimumat 0.5 M urea.展开更多
The intrinsic viscosity and viscometric interaction parameters of perfluorosulfonic acid （PFSA） and poly（vinyl alcohol） （PVA） were measured by dilute solution viscometry. The miscibility between PFSA and PVA was...The intrinsic viscosity and viscometric interaction parameters of perfluorosulfonic acid （PFSA） and poly（vinyl alcohol） （PVA） were measured by dilute solution viscometry. The miscibility between PFSA and PVA was estimated by the criteria of AB and μ. The results indicated that PFSA and PVA were completely miscible for any weight fraction in aqueous solution.展开更多
Erwinia(E) gum is composed of glucose, fucose, galactose and glucuronic acid. The weightaverage molecular weights M w, numberaverage molecular weights M n and intrinsic viscosities[η] of the four fractions and the ...Erwinia(E) gum is composed of glucose, fucose, galactose and glucuronic acid. The weightaverage molecular weights M w, numberaverage molecular weights M n and intrinsic viscosities[η] of the four fractions and the unfractionated E gum in aqueous solutions at desired temperatures were studied by light scattering, membrane osmometry, size exclusion chromatography(SEC) and viscometry. The experimental results prove that E gum formed aggregates in the aqueous solution at 25 ℃ and the aggregates were broken gradually with increasing temperature. The dissociation of the aggregates of E gum in the aqueous solution started at 36 ℃, and was completed at around 90 ℃. The [η] values of E gum and its fractions are much higher than those of the conventional polymers with the similar molecular weights, and decrease with increasing NaCl concentration.展开更多
Critical concentrations of α-(1→3)-D-glucan L-FV-Ⅱ from Lentinus edodes were studied by viscometry andfluorescence probe techniques. The dependence of the reduced viscosity on concentration of the glucan in 0.5 mol...Critical concentrations of α-(1→3)-D-glucan L-FV-Ⅱ from Lentinus edodes were studied by viscometry andfluorescence probe techniques. The dependence of the reduced viscosity on concentration of the glucan in 0.5 mol/L NaOHaqueous solutions with or without urea showed two turning points corresponding to the dynamic contact concentration c_s andthe overlap concentration c~* of the polymer. The values of c_s and c~* were found to be 1×10^(-3) g cm^(-3) and 1.1×10^(-2) g cm^(-3),respectively, for L-FV-Ⅱ in 0.5 mol/L NaOH aqueous solutions. The two critical concentrations of L-FV-Ⅱ in 0.5 mol/LNaOH aqueous solutions were also found to be 1.2×10^(-3) g cm^(-3) fbr c_s and 9.2×10^(-3) g cm^(-3) for c~* from the concentrationdependence of phenanthrene fluorescence intensities. The overlap concentration c~* of L-FV-Ⅱ in 0.5 mol/L NaOH aqueoussolutions was lower than that of polystyrene with same molecular weight in benzene, owing to the fact that polysaccharidetends to undergo aggregation caused by intermolecular hydrogen bonding. A normal viscosity behavior of L-FV-Ⅱ in 0.5 mol/L urea/0.5 mol/L NaOH aqueous solutions can still be observed in an extremely low concentration range at 25℃.展开更多
Association behavior of ethylene vinyl acetate (EVA) copolymer in foursolvents 1, 2-dichloroethane (DCE), cyclohexane (CYH), xylene (XYL) and chloroform(CF) has been investigated by dilute solution viscometry The crit...Association behavior of ethylene vinyl acetate (EVA) copolymer in foursolvents 1, 2-dichloroethane (DCE), cyclohexane (CYH), xylene (XYL) and chloroform(CF) has been investigated by dilute solution viscometry The critical association concen-tration (C_A) was determined at which the incipient decrease in slope of the η_(sp)/C～ Ccurve in solutions at the dilute regime. Our results showed that whether the CA couldexist depends on solvent property. The values of CA in DCE increase with increasing, oftemperature and vinyl acetate (VA) content in EVA and decreasing of molecular weight ofEVA.展开更多
The intermolecular interaction between poly(methyl methacrylate) (PMMA) and polystyrene (PS) intetrahydrofuran (THF) and N,N'-dimethyl formamide (DMF) solvents was studied at 28℃ using a dilute solution viscometr...The intermolecular interaction between poly(methyl methacrylate) (PMMA) and polystyrene (PS) intetrahydrofuran (THF) and N,N'-dimethyl formamide (DMF) solvents was studied at 28℃ using a dilute solution viscometrymethod. Solvent is believed to play a key role in characterizing the viscosity behavior of the polymer solution. The intrinsicviscosity and viscosity interaction parameter were experimentally measured for the binary (solvent/polymer) and for theternary systems in two solvents. The compatibility of the polymer mixture was discussed in terms of the sign of △b_m. Theresults show that the compatibility of PMMA/PS blend in DMF is larger than that in THF.展开更多
The thermal aging behavior of poly （ vinyl alcohol ） （ PVA ） hydrogel was studied at four different temperatures of 40 ℃, 50 ℃, 60 ℃ and 70 ℃ in one year. The samples of PVA hydrogel were closely covered by pl...The thermal aging behavior of poly （ vinyl alcohol ） （ PVA ） hydrogel was studied at four different temperatures of 40 ℃, 50 ℃, 60 ℃ and 70 ℃ in one year. The samples of PVA hydrogel were closely covered by plastic film. The changes of their chemical structures and physical properties during aging were measured through different measurable techniques including tensile testing, gel permeation chromatography （ GPC ）, viscosity analysis, and Fourier transform infrared （FTIR） spec- trum. The results showed that the molecular weight of PVA in hydrogel changed little with time and temperature. FTIR spectra of PVA in all the samples were similar to those of the original samples. The tensile strength of PVA hydrogel didn＇t change until the 330th days.展开更多
The Interaction between vitamin B12 （VBI2） and fish sperm DNA was investigated in physiological buffer （pH 7.4） using the methylene blue （MB） dye as a spectral probe by spetcrophotometery, viscosity measurements...The Interaction between vitamin B12 （VBI2） and fish sperm DNA was investigated in physiological buffer （pH 7.4） using the methylene blue （MB） dye as a spectral probe by spetcrophotometery, viscosity measurements and cyclic voltammetry. The apparent binding constant of vitamin B12 with DNA was found to be 3.2 × 10^5 mol^-1·L. The voltammetric behavior of vitamin B12 has been investigated at glassy carbon electrode using cyclic voltammetry. Thermodynamic parameters including △H^0, △S^0 and △G^0 for the interaction between VB12 and DNA have determined as -2.3 × 10^4, 27.54 and -3.1 × 10^4j·mol^-l·K^-1 respectively. One indication of DNA binding mode with VBI2 was the change in viscosity when a small molecule associates with DNA. The diffusion coefficients of VB12 in the absence （D0）f and presence of DNA （D0）b was calculated as 5.04 × 10^-6 and 1.13 × 10^-6 cm^2·s^-1 respectively. The results indicated that vitamin B12 can bind to DNA and the major binding mode was intercalative binding.展开更多
The molecular weight distributions were estimated for carbon fiber polymer precursors such as poly（acrylonitrile-co-itaconic acid） synthesized by semi batch solution polymerization in mixed solvents media with the a...The molecular weight distributions were estimated for carbon fiber polymer precursors such as poly（acrylonitrile-co-itaconic acid） synthesized by semi batch solution polymerization in mixed solvents media with the azonitrile compounds as initiator under the different ratios of solvent and non solvent from 0.75 to 2.5 in weight. The copolymer was characterized by using Fourier transform infrared spectroscopy （FTIR） and nuclear magnetic resonance （1H-NMR） analyses. The molecular weight distributions were evaluated by Mv/Mn ratios estimated from viscosity and osmotic measurements, and Mw/Mn estimated from size exclusion chromatography. The molecular weight distributions of these polymers as determined from M, JMn and Mw/Mn are 2.9 to 3,2 and 2.0 to 2.5 respectively. The molecular distributions were close to a narrow distribution of 2.0 when the solvent/non-solvent ratio was varied between 1.4 and 2.0. Intrinsic viscosity [η] as a function of molecular weight of poly（acrylonitrile-co-itaconic acid） was evaluated by means of low angle laser light scattering with size exclusion chromatography （SEC-LALLS） and viscometry with SEC （SEC-VISCO）. The relationship between [η] and Mw for poly（acrylonitrile-co-itaconic acid） in DMF at 50℃ was [q] = 1.1×10-5 Mw0.79, where [η] is obtained in dL/g.展开更多
文摘The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results show thatthe polymer mixtures are compatible in DMF solution in the absence of urea. The influence of urea addition on the degree ofcompatibility of the polymer mixtures has been studied in terms of the compatibility parameters (△b_m and △[η]_m). It wasfound that the compatibility of the polymer mixtures is decreased with increasing urea addition, passing through a minimumat 0.5 M urea.
基金supported by the Innovation Program of Shanghai Municipal Education Commission (Grant No.09YZ163)
文摘The intrinsic viscosity and viscometric interaction parameters of perfluorosulfonic acid （PFSA） and poly（vinyl alcohol） （PVA） were measured by dilute solution viscometry. The miscibility between PFSA and PVA was estimated by the criteria of AB and μ. The results indicated that PFSA and PVA were completely miscible for any weight fraction in aqueous solution.
基金Supported by the National Natural Science Foundation of China
文摘Erwinia(E) gum is composed of glucose, fucose, galactose and glucuronic acid. The weightaverage molecular weights M w, numberaverage molecular weights M n and intrinsic viscosities[η] of the four fractions and the unfractionated E gum in aqueous solutions at desired temperatures were studied by light scattering, membrane osmometry, size exclusion chromatography(SEC) and viscometry. The experimental results prove that E gum formed aggregates in the aqueous solution at 25 ℃ and the aggregates were broken gradually with increasing temperature. The dissociation of the aggregates of E gum in the aqueous solution started at 36 ℃, and was completed at around 90 ℃. The [η] values of E gum and its fractions are much higher than those of the conventional polymers with the similar molecular weights, and decrease with increasing NaCl concentration.
基金This work was supported by the National Natural Science Foundation of China (No. 29374170) and the Research Grant Council of Hong Kong Government Earmarked Grant (CUHK 4161/99M).
文摘Critical concentrations of α-(1→3)-D-glucan L-FV-Ⅱ from Lentinus edodes were studied by viscometry andfluorescence probe techniques. The dependence of the reduced viscosity on concentration of the glucan in 0.5 mol/L NaOHaqueous solutions with or without urea showed two turning points corresponding to the dynamic contact concentration c_s andthe overlap concentration c~* of the polymer. The values of c_s and c~* were found to be 1×10^(-3) g cm^(-3) and 1.1×10^(-2) g cm^(-3),respectively, for L-FV-Ⅱ in 0.5 mol/L NaOH aqueous solutions. The two critical concentrations of L-FV-Ⅱ in 0.5 mol/LNaOH aqueous solutions were also found to be 1.2×10^(-3) g cm^(-3) fbr c_s and 9.2×10^(-3) g cm^(-3) for c~* from the concentrationdependence of phenanthrene fluorescence intensities. The overlap concentration c~* of L-FV-Ⅱ in 0.5 mol/L NaOH aqueoussolutions was lower than that of polystyrene with same molecular weight in benzene, owing to the fact that polysaccharidetends to undergo aggregation caused by intermolecular hydrogen bonding. A normal viscosity behavior of L-FV-Ⅱ in 0.5 mol/L urea/0.5 mol/L NaOH aqueous solutions can still be observed in an extremely low concentration range at 25℃.
基金This work was supported by the National Natural Science Foundation of China(No.29474168)
文摘Association behavior of ethylene vinyl acetate (EVA) copolymer in foursolvents 1, 2-dichloroethane (DCE), cyclohexane (CYH), xylene (XYL) and chloroform(CF) has been investigated by dilute solution viscometry The critical association concen-tration (C_A) was determined at which the incipient decrease in slope of the η_(sp)/C～ Ccurve in solutions at the dilute regime. Our results showed that whether the CA couldexist depends on solvent property. The values of CA in DCE increase with increasing, oftemperature and vinyl acetate (VA) content in EVA and decreasing of molecular weight ofEVA.
文摘The intermolecular interaction between poly(methyl methacrylate) (PMMA) and polystyrene (PS) intetrahydrofuran (THF) and N,N'-dimethyl formamide (DMF) solvents was studied at 28℃ using a dilute solution viscometrymethod. Solvent is believed to play a key role in characterizing the viscosity behavior of the polymer solution. The intrinsicviscosity and viscosity interaction parameter were experimentally measured for the binary (solvent/polymer) and for theternary systems in two solvents. The compatibility of the polymer mixture was discussed in terms of the sign of △b_m. Theresults show that the compatibility of PMMA/PS blend in DMF is larger than that in THF.
文摘The thermal aging behavior of poly （ vinyl alcohol ） （ PVA ） hydrogel was studied at four different temperatures of 40 ℃, 50 ℃, 60 ℃ and 70 ℃ in one year. The samples of PVA hydrogel were closely covered by plastic film. The changes of their chemical structures and physical properties during aging were measured through different measurable techniques including tensile testing, gel permeation chromatography （ GPC ）, viscosity analysis, and Fourier transform infrared （FTIR） spec- trum. The results showed that the molecular weight of PVA in hydrogel changed little with time and temperature. FTIR spectra of PVA in all the samples were similar to those of the original samples. The tensile strength of PVA hydrogel didn＇t change until the 330th days.
文摘The Interaction between vitamin B12 （VBI2） and fish sperm DNA was investigated in physiological buffer （pH 7.4） using the methylene blue （MB） dye as a spectral probe by spetcrophotometery, viscosity measurements and cyclic voltammetry. The apparent binding constant of vitamin B12 with DNA was found to be 3.2 × 10^5 mol^-1·L. The voltammetric behavior of vitamin B12 has been investigated at glassy carbon electrode using cyclic voltammetry. Thermodynamic parameters including △H^0, △S^0 and △G^0 for the interaction between VB12 and DNA have determined as -2.3 × 10^4, 27.54 and -3.1 × 10^4j·mol^-l·K^-1 respectively. One indication of DNA binding mode with VBI2 was the change in viscosity when a small molecule associates with DNA. The diffusion coefficients of VB12 in the absence （D0）f and presence of DNA （D0）b was calculated as 5.04 × 10^-6 and 1.13 × 10^-6 cm^2·s^-1 respectively. The results indicated that vitamin B12 can bind to DNA and the major binding mode was intercalative binding.
基金financially supported by the Council of Scientific and Industrial Research,New Delhi under Supra Institutional Project(SIP-IFCAP-04)
文摘The molecular weight distributions were estimated for carbon fiber polymer precursors such as poly（acrylonitrile-co-itaconic acid） synthesized by semi batch solution polymerization in mixed solvents media with the azonitrile compounds as initiator under the different ratios of solvent and non solvent from 0.75 to 2.5 in weight. The copolymer was characterized by using Fourier transform infrared spectroscopy （FTIR） and nuclear magnetic resonance （1H-NMR） analyses. The molecular weight distributions were evaluated by Mv/Mn ratios estimated from viscosity and osmotic measurements, and Mw/Mn estimated from size exclusion chromatography. The molecular weight distributions of these polymers as determined from M, JMn and Mw/Mn are 2.9 to 3,2 and 2.0 to 2.5 respectively. The molecular distributions were close to a narrow distribution of 2.0 when the solvent/non-solvent ratio was varied between 1.4 and 2.0. Intrinsic viscosity [η] as a function of molecular weight of poly（acrylonitrile-co-itaconic acid） was evaluated by means of low angle laser light scattering with size exclusion chromatography （SEC-LALLS） and viscometry with SEC （SEC-VISCO）. The relationship between [η] and Mw for poly（acrylonitrile-co-itaconic acid） in DMF at 50℃ was [q] = 1.1×10-5 Mw0.79, where [η] is obtained in dL/g.
