Viscosity – Molecular Weight Relationships and Unperturbed Dimensions of Linear Chain Molecules

Characteristics of solid-state batteries with zinc/cadmium halide-doped silver phosphate glasses as electrolytes

Physical properties of polyelectrolytes have been shown to be significantly related to their chain conformations. Atomistic simulation has been used as an effective method for studying polymer chain structures, but few simulations have focused on the effects of chain length and tacticity in the presence of monovalent salts. This paper investigated the microscopic conformation behaviors of poly(acrylic acid) (PAA) with different chain sizes, tacticities, and sodium chloride concentrations. The hydrogen behaviors and corresponding radial distribution functions were obtained. The results showed that the increase of salt concentrations led to the collapse of PAA chains, especially for longer chains. It was found that the effects of salt were mainly attributed to the shielding screening effect by sodium ions rather than the hydrogen bonding effect. Two different structures were formed by isotactic PAA and syndiotactic PAA, respectively, which were due to the deprotonation patterns along the PAA chain.

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Atomistic Molecular Dynamic Simulation of Dilute Poly(acrylic acid) Solution: Effects of Simulation Size Sensitivity and Ionic Strength

Infrared spectroscopic studies of ion-conducting silver phosphate glasses doped with zinc and cadmium halides

Lead arsenate glasses containing different concentrations of NiO ranging from 0 to 1 mol% (in steps of 0.2 mol%) were prepared. The samples were characterized by X-ray diffraction and differential thermal analysis. A number of studies viz., optical absorption, thermoluminescence, magnetic susceptibilities and IR spectra, have been carried out on these glasses. The bands observed in the optical absorption spectra of the glasses have been analyzed using Tanabe–Sugano diagrams for d8 ion; the analysis indicates the presence of Ni2+ ions in both tetrahedral and octahedral positions. The increase in the concentration of NiO in the glass matrix shows a gradual transformation of nickel ions from tetrahedral positions to octahedral positions in the glass network. The thermoluminescence light output of the X-ray irradiated glasses has exhibited a glow peak at 353 K (with increasing intensity with an increase in the concentration of NiO) in addition to the conventional peak due to the recombination of electron–hole centers; this glow peak is identified due to 3T2 → 3A2 emission transition of octahedral Ni2+ ions. The value of the magnetic moment evaluated from the measured magnetic susceptibility show a decreasing trend from 3.84 to 3.10 μB with the increase in the concentration of NiO. All these studies indicate an increasing presence of octahedral (lasing) Ni2+ ions in these glasses with the increase in the concentration of NiO.

Spectroscopic studies of lead arsenate glasses doped with nickel oxide

A number of samples of sodium potassium (Na:K=9:1 to 3:7) and lithium potassium (Li:K=9:1 to 5:5) copolyphosphates were prepared and characterized. Their number-average molecular weights were determined by end-group titration and intrinsic viscosities were determined in 0.035 N NaBr solution. Intrinsic viscosity–molecular weight relationships according to the Mark–Houwink equation were established for each series of compounds. A highly interesting feature of the results obtained was a decrease in the value of the constant a with an increase in the mole fraction of potassium in the copolyphosphates. This is a remarkable demonstration of the dependence of a on the degree of solvation; the solubilities of both kinds of copolyphosphates were found to decrease with an increase in the proportion of potassium.

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Intrinsic viscosity-molecular weight relationships in copolyphosphates

A comparative study of the catalytic action of water-miscible organic solvents on the hydrolytic degradation of long-chain polyphosphates

The results of viscosity measurements on several samples of lithium-potassium copolyphosphates (Li:K ratio ranging from 9:1 to 5:5) in salt-free aqueous solutions and in theta solvents are reported. Molecular weights determined by end-group titration ranged from 4000–10000. In aqueous solutions the Fuoss equation parameter A was found to be nearly proportional to the square of molecular weights, indicating rod-like structures of the poly-ions at infinite dilution. The concentrations of NaBr solutions acting as theta solvents at 35°C were determined for all cases and the viscosity data in θ-solvents were utilized in calculating unperturbed dimensions which were found to lie in the range 4.7×10−7 cm to 7.4×10−7 cm.

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Viscosities of Copolyphosphates in Salt-Free Aqueous Solutions and Theta Solvents I.

The results obtained by testing the PALIT equation 100ϱ0[η] + In M = K1M2/3 + K2 with solutions of some polyphosphates and copolyphosphates have been analyzed and compared with the MARK-HOUWINK relationship. The values of the exponent a in the MARK-HOUWINK relationship were found to be higher for those samples which have higher values of K1 or lower values of K2 in the equation suggested by PALIT.



Die bei Anwendung der PALIT-Beziehung 100ϱ0[η] + In M = K1M2/3 + K2 auf Losungen einiger Polyphosphate und Copolyphosphate erhaltenen Ergebnisse wurden analysiert und mit der MARK-HOUWINK-Beziehung verglichen. Die Werte des Exponenten a in der MARK-HOUWINK-Beziehung sind fur die Proben groser, die grosere Werte K1 oder Kleinere Werte K2 in der von PALIT vorgeschlagenen Gleichung ergeben.

Viscosity relationships for polyphosphates and copolyphosphates

Sodium polyphosphate and sodium–copper and sodium–nickel copolyphosphate glasses (with the ratio Na : M = 9 : 1 and 8 : 2, where M is Cu or Ni) are studied. The glass transition (Tg) and melting (Tm) temperatures are determined by differential scanning calorimetry (DSC). It is revealed that the Tgand Tmtemperatures depend on the molecular weight Mt(determined from terminal groups) of polymeric glasses, the Na : M ratio, and the glass synthesis conditions. The activation energies are calculated, and the thermodynamic parameters ΔH, ΔS, and Cpare measured.

H. N. Bhargava

Papers

Intrinsic viscosity-molecular weight relationships in copolyphosphates

A comparative study of the catalytic action of water-miscible organic solvents on the hydrolytic degradation of long-chain polyphosphates

Viscosities of Copolyphosphates in Salt-Free Aqueous Solutions and Theta Solvents I.

Viscosity relationships for polyphosphates and copolyphosphates

A Study of Sodium–Copper and Sodium–Nickel Polyphosphate Glasses by Differential Scanning Calorimetry1