The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Bijan Das - One of the best experts on this subject based on the ideXlab platform.
-
influence of temperature added electrolyte and polymer molecular weight on the counterion condensation phenomenon in aqueous solution of sodium polystyrenesulfonate a scaling theory approach
RSC Advances, 2015Co-Authors: Dhiman Ray, Bijan DasAbstract:Interactions between a polyion and its counterions in aqueous solutions of an anionic polyelectrolyte sodium polystyrenesulfonate in the presence of sodium chloride were investigated using electrical Conductivity as the probe. The specific Conductivity vs. polyelectrolyte concentration data were analyzed with an equation recently developed by us considering the scaling description for the conformation of a polyion chain. The influences of (a) the molecular weight and the concentration of the polyelectrolyte, (b) the added electrolyte concentration, and (c) the temperature on polyion–counterion interactions were investigated. The extent of counterion condensation was found to be greatly affected by the concentration and molecular weight of the polyelectrolyte, the concentration of the added electrolyte, and the temperature. The polyion Equivalent Conductivity in conjunction with the derived coefficient of friction between the monomer units and the solvent provided important information concerning the relative importance of the size and charge of the polyions. The overall results have been elucidated taking the medium dielectric constant, the hydration behaviour of the counterions, and the coiling behavior of the polyion chains into account. The present study provides new insight as to how the polyelectrolyte molecular weight influences the counterion condensation behaviour in a polyelectrolyte solution in the presence of an added electrolyte.
-
The Effects of Concentration, Relative Permittivity and Temperature on the Transport Properties of Sodium Polystyrenesulphonate in Methanol–Water Mixed Solvent Media
Journal of Polymer Research, 2006Co-Authors: Ajaya Bhattarai, Prabir Nandi, Bijan DasAbstract:Precise measurements on the electrical Conductivity of solutions of sodium polystyrenesulphonate in methanol–water mixed solvent media containing 8, 16, 25, and 34 wt.% of methanol at 308.15, 313.15, 318.15, and 323.15 K are reported. The degree of substitution of sodium polystyrenesulphonate used was 1, and the concentrations were varied from ∼2.0 × 10^−4 to ∼4.0 × 10^−3 monomol l^−1. The results showed a slight and monotonous increase in the Equivalent Conductivity with decreasing polyelectrolyte concentration. The applicability of the Manning’s theory for salt-free polyelectrolyte solution was examined and a major discrepancy against the theory was observed. The calculated values of the Equivalent Conductivity deduced on the basis of this theory were found to be lower than the experimental ones. Possible reasons for this discrepancy have been discussed. The effects of the temperature and relative permittivity of the medium on the Equivalent Conductivity were also investigated. Estimation of the fractions of uncondensed counterions provides important insight regarding the solution behavior of the polyelectrolyte in methanol–water mixtures.
Ajaya Bhattarai - One of the best experts on this subject based on the ideXlab platform.
-
Interaction behavior of polyion-counterion for sodium polystyrene sulfonate.
Data in brief, 2019Co-Authors: Ajaya BhattaraiAbstract:Abstract The specific conductances are measured for sodium polystyrene sulfonate in water and methanol-water mixture. The Equivalent Conductivity data against concentration are evaluated by scaling concept. The effects of the solvent composition and the polyelectrolyte concentration on the fractions of uncondensed counterions ( f ) , the polyion conductivities λ p , the standard state free energies of counterion association Δ G A o , and the polyion transference number T P are calculated. The charge density ( ξ ) of sodium polystyrene sulfonate was used for the research article [1] to see the variation of the critical aggregation concentration of cetyltrimethyl ammonium bromide in sodium polystyrene sulfonate against the charge density of sodium polystyrene sulfonate.
-
Electrical Conductivity of sodium polystyrenesulfonate in acetonitrile–water-mixed solvent media: experiment and data analysis using the Manning counterion condensation model and the scaling theory approach
Colloid and Polymer Science, 2009Co-Authors: Debapratim Ghosh, Ajaya BhattaraiAbstract:Precise measurements on the electrical Conductivity of sodium polystyrenesulfonate in acetonitrile–water-mixed solvent media containing 20 and 40 vol.% of acetonitrile at 308.15, 313.15, and 318.15 K are reported. The mobility of the polyelectrolyte solute was found to be influenced by the polyelectrolyte concentration, the relative permittivity of the medium, and the temperature. The Manning counterion condensation theory for salt-free polyelectrolyte solution failed to describe the experimental results. The data have, therefore, been analyzed on the basis of a new model for semidilute polyelectrolyte Conductivity which takes into account the scaling arguments to obtain the fractions of uncondensed counterions which were found to depend on the polyelectrolyte concentration. The effects of the temperature and the relative permittivity of the medium on the Equivalent Conductivity as well as on the fraction of uncondensed counterions have also been discussed.
-
The Effects of Concentration, Relative Permittivity and Temperature on the Transport Properties of Sodium Polystyrenesulphonate in Methanol–Water Mixed Solvent Media
Journal of Polymer Research, 2006Co-Authors: Ajaya Bhattarai, Prabir Nandi, Bijan DasAbstract:Precise measurements on the electrical Conductivity of solutions of sodium polystyrenesulphonate in methanol–water mixed solvent media containing 8, 16, 25, and 34 wt.% of methanol at 308.15, 313.15, 318.15, and 323.15 K are reported. The degree of substitution of sodium polystyrenesulphonate used was 1, and the concentrations were varied from ∼2.0 × 10^−4 to ∼4.0 × 10^−3 monomol l^−1. The results showed a slight and monotonous increase in the Equivalent Conductivity with decreasing polyelectrolyte concentration. The applicability of the Manning’s theory for salt-free polyelectrolyte solution was examined and a major discrepancy against the theory was observed. The calculated values of the Equivalent Conductivity deduced on the basis of this theory were found to be lower than the experimental ones. Possible reasons for this discrepancy have been discussed. The effects of the temperature and relative permittivity of the medium on the Equivalent Conductivity were also investigated. Estimation of the fractions of uncondensed counterions provides important insight regarding the solution behavior of the polyelectrolyte in methanol–water mixtures.
Kenzo Miya - One of the best experts on this subject based on the ideXlab platform.
-
discussion on the Equivalent Conductivity and resistance of stress corrosion cracks in eddy current simulations
Ndt & E International, 2009Co-Authors: Noritaka Yusa, Kenzo MiyaAbstract:This study evaluates the numerical modeling of stress corrosion cracks from the viewpoint of eddy current simulations. Five stress corrosion cracks are artificially introduced into austenitic stainless steel plates measuring 25 mm in thickness, and then eddy current inspections are conducted to gather eddy current signals and destructive tests performed to confirm the true profiles of the cracks. The cracks are carefully introduced so as not to cluster, and the data obtained enables discussion of the modeling of a single crack quantitatively. Subsequent numerical simulations model each crack as a rectangular region with a fixed width and uniform Conductivity, and evaluate the Equivalent width and Conductivity suitable for modeling the crack. The evaluation reveals that it is not reasonable to correlate the size of a crack and only its width or Conductivity, and larger cracks tend to have greater resistance, which is defined as the width divided by Conductivity. Furthermore, the values of width and Conductivity depend also on the exciting frequency and probe used; however, the resistance remains almost unchanged by the experimental condition.
Noritaka Yusa - One of the best experts on this subject based on the ideXlab platform.
-
evaluation of stress corrosion cracking as a function of its resistance to eddy currents
Nuclear Engineering and Design, 2009Co-Authors: Noritaka Yusa, Hidetoshi HashizumeAbstract:This study discusses the Equivalent Conductivity, the Equivalent width, and the Equivalent resistance of stress corrosion cracks from the viewpoint of eddy current testing. Four artificial stress corrosion cracks were prepared for this study, and their eddy current signals were gathered using two absolute pancake probes and two differential type plus point probes. Then their numerical models were evaluated using finite element simulations on the basis of the measured eddy current signals and their profiles revealed by destructive tests. The results of this study revealed that whereas the Equivalent Conductivity and the Equivalent width depend on the exciting frequency utilized, the Equivalent resistance of a crack has much less dependency, which agrees well with an earlier report. This study also revealed that the resistance of a crack depends on probe utilized. Larger probes tend to lead to smaller crack resistance. Pancake type probes tend to lead to larger crack resistance than plus point probes. Analyzing the results together with earlier reports indicates that cracks with a large Equivalent Conductivity tend to have large Equivalent width, and supports the validity of assuming the minimum resistance of a stress corrosion crack whereas considering the Conductivity and the width individually would not be viable.
-
discussion on the Equivalent Conductivity and resistance of stress corrosion cracks in eddy current simulations
Ndt & E International, 2009Co-Authors: Noritaka Yusa, Kenzo MiyaAbstract:This study evaluates the numerical modeling of stress corrosion cracks from the viewpoint of eddy current simulations. Five stress corrosion cracks are artificially introduced into austenitic stainless steel plates measuring 25 mm in thickness, and then eddy current inspections are conducted to gather eddy current signals and destructive tests performed to confirm the true profiles of the cracks. The cracks are carefully introduced so as not to cluster, and the data obtained enables discussion of the modeling of a single crack quantitatively. Subsequent numerical simulations model each crack as a rectangular region with a fixed width and uniform Conductivity, and evaluate the Equivalent width and Conductivity suitable for modeling the crack. The evaluation reveals that it is not reasonable to correlate the size of a crack and only its width or Conductivity, and larger cracks tend to have greater resistance, which is defined as the width divided by Conductivity. Furthermore, the values of width and Conductivity depend also on the exciting frequency and probe used; however, the resistance remains almost unchanged by the experimental condition.
Dhiman Ray - One of the best experts on this subject based on the ideXlab platform.
-
influence of temperature added electrolyte and polymer molecular weight on the counterion condensation phenomenon in aqueous solution of sodium polystyrenesulfonate a scaling theory approach
RSC Advances, 2015Co-Authors: Dhiman Ray, Bijan DasAbstract:Interactions between a polyion and its counterions in aqueous solutions of an anionic polyelectrolyte sodium polystyrenesulfonate in the presence of sodium chloride were investigated using electrical Conductivity as the probe. The specific Conductivity vs. polyelectrolyte concentration data were analyzed with an equation recently developed by us considering the scaling description for the conformation of a polyion chain. The influences of (a) the molecular weight and the concentration of the polyelectrolyte, (b) the added electrolyte concentration, and (c) the temperature on polyion–counterion interactions were investigated. The extent of counterion condensation was found to be greatly affected by the concentration and molecular weight of the polyelectrolyte, the concentration of the added electrolyte, and the temperature. The polyion Equivalent Conductivity in conjunction with the derived coefficient of friction between the monomer units and the solvent provided important information concerning the relative importance of the size and charge of the polyions. The overall results have been elucidated taking the medium dielectric constant, the hydration behaviour of the counterions, and the coiling behavior of the polyion chains into account. The present study provides new insight as to how the polyelectrolyte molecular weight influences the counterion condensation behaviour in a polyelectrolyte solution in the presence of an added electrolyte.