scholarly journals Probing Uranium(IV) Hydrolyzed Colloids and Polymers by Light Scattering

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
N. Priyadarshini ◽  
M. Sampath ◽  
Shekhar Kumar ◽  
U. Kamachi Mudali ◽  
R. Natarajan
Keyword(s):  
Light Scattering ◽  
Virial Coefficient ◽  
Average Molecular Weight ◽  
Second Virial Coefficient ◽  
Solvent Interaction ◽  
Stable Suspension ◽  
Crystalline Nature ◽  
Hydrolysis Of ◽  
Colloid Formation ◽  
Light Scattering Technique

Tetravalent uranium readily undergoes hydrolysis even in highly acidic aqueous solutions. In the present work, solutions ranging from 0.4 to 19 mM (total U) concentration (1<pH<4) are carefully investigated by light scattering technique with special emphasis on polymerization leading to colloid formation. The results clearly indicate that the concentration has significant effect on particle size as well as stability of colloids. With increasing concentration the size of colloids formed is smaller due to more crystalline nature of the colloids. Stability of colloids formed at lower concentration is greater than that of colloids formed at higher concentration. Weight average molecular weight of the freshly prepared and colloidal polymers aged for 3 days is determined from the Debye plot. It increases from 1,800 to 13,000 Da. 40–50 atoms of U are considered to be present in the polymer. Positive value of second virial coefficient shows that solute-solvent interaction is high leading to stable suspension. The results of this work are a clear indication that U(IV) hydrolysis does not differ from hydrolysis of Pu(IV).

scholarly journals Particle Size Variation and Prediction of Molecular Weight of Bi(III) Hydrolyzed Polymer Using Light Scattering Technique

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
N. Priyadarshini ◽  
M. Sampath ◽  
Shekhar Kumar ◽  
U. Kamachi Mudali
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Light Scattering ◽  
Second Virial Coefficient ◽  
Size Variation ◽  
Degree Of Polymerization ◽  
High Concentration ◽  
Naoh Solution ◽  
Colloid Formation ◽  
Light Scattering Technique

The present paper gives an overview of the hydrolysis reactions up to colloid formation of Bi(III) in aqueous nitric acid medium using light-scattering measurements. The hydrolysis products of Bi were polynuclear complexes such as dimers, pentamers, and the most important is the hexameric species. In the present investigation Bi3+ polymers were prepared by diluting different concentrations of Bi(NO3)3·5H2O solutions to pH 1 ± 0.1 by adding 0.1 M NaOH solution as it starts to precipitates at pH 1.4. The degree of polymerization was found to be 5-6 units. Particle size measurements were performed, and it has been found that particle size increases at high concentration of Bi due to aggregation. Refractive index measurements were also performed. The molecular weight of hydrolyzed polymeric species of Bi was determined by using Debye plot, and it was estimated as 1236 Da. The second virial coefficient was found to be 6.24 × 10−3 mLg−1 Da. The present investigation confirms that the predominant complex in the solution has 5-6 Bi atoms.

Size, Form and Flexibility of the Rubber Molecule

1962 ◽  
Vol 35 (4) ◽  
pp. 908-917 ◽  
Author(s):  
G. V. Schulz ◽  
A. Mula
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Light Scattering ◽  
Virial Coefficient ◽  
Second Virial Coefficient ◽  
Quantitative Measure ◽  
Degree Of Polymerization ◽  
Bromine Content ◽  
Angle Scattering ◽  
Gaussian Density

Abstract Natural rubber can be brominated in dilute cyclohexane solution, whereby the molecular weight, corresponding to the bromine content, increases. For brominated rubber, increasing bromine content makes cyclohexane an increasingly poorer solvent, which is shown by a contraction of the molecule coils and a decrease in the second virial coefficient. Quantitative results were obtained through viscosity and light scattering measurements. Cyclohexane solutions of brominated rubber containing about 43% bromine have a θ point at room temperature. Here the second virial coefficient is zero and the coil has an ideal Gaussian density distribution. In this state the coil diameter is about 1.6 times bigger than for completely free rotation. A comparison of these data with X-ray low angle scattering could yield a quantitative measure of possible molecular branching. Brominated rubber with about one bromine per isoprene residue is a good starting material for the preparation of electron-microscope samples which can be used for the determination of the molecular weight distribution in rubber. The value of the weight average degree of polymerization determined by an electron microscope is in agreement with that determined through (1) light scattering and (2) ultracentrifuge and diffusion measurements. The molecular inhomogeneity of our sample is of the order of 0.5.

scholarly journals Specific refractive index increments of inulin

2001 ◽  
Vol 66 (6) ◽  
pp. 397-401 ◽  
Author(s):  
Goran Nikolic ◽  
Milorad Cakic ◽  
Ljubomir Ilic
Keyword(s):  
Refractive Index ◽  
Light Scattering ◽  
Approximate Method ◽  
Virial Coefficient ◽  
Molar Mass ◽  
Laser Light ◽  
Second Virial Coefficient ◽  
Laser Light Scattering ◽  
Operating Wavelength ◽  
Differential Refractometer

The specific refractive index increments (dn/dc) of inulin in water, at 25 ?C, were measured at different wavelengths (436, 546 and 589 nm) using a BP-differential refractometer. The dn/dc at the operating wavelength (633 nm) of the laser light scattering photometer was calculated by an approximate method. This value can be used to determine the absolute molar mass and the second virial coefficient of inulin by light scattering photometry.

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