V. P. Budtov

Thermodynamics and viscosities of dilute polymer solutions in binary solvents

Experiments aimed at comparison of calculated and experimental intrinsic viscosities of PS and PMMA in some binary solvents used as eluents in chromatography are performed. The intrinsic viscosities are determined in mixed solvents of different thermodynamic qualities, including a θ solvent, in a wide composition range. The analysis of the thermodynamic and rheological theoretical equations for ternary systems allowed the interpretation of anomalies observed on the experimental curves of intrinsic viscosity versus solvent composition.

Effect of organoaluminum compound on kinetic nonuniformity and structure of active centers of neodymium catalytic systems in butadiene polymerization

The effect of organoaluminum compound nature on the kinetic nonuniformity of the active centers of neodymium-containing catalytic systems at butadiene polymerization was studied. The concentrations of each type of active centers were calculated.

Determination of a cumulative distribution function of kinetic activity of lanthanide ion-coordination catalytic systems used for diene polymerization

Abstract From the experimentally obtained of curves 1,4-cis-polybutadiene molecular weight-distribution the cumulative distribution functions on kinetic activity of polymerization centers of NdCl33L-Al(i-C4H9)3 catalytic system are obtained by the Tikhonov regularization procedure. At least four types of active sites distinguished by kinetic activity are detected. The influence of polymerization condition and concentration of the components of the polymerization system on a modification of their activity is shown.

The physical chemistry of a maleic acid-hex-1-ene copolymer and of its neutralized samples in dilute solutions☆

Abstract Viscosity, diffusion and light scattering measurements were used to study a maleic acid-hex-1-ene copolymer (MHC) in solvents with different polarities. The use of DMF + 0·05 n NaI as solvent gave rise to a secondary MHC macromolecular structure which was due to intramolecular reactions of the alkyl radicals present in the branches. The copolymer takes up the conformation of a non-permeated, flexible Gaussian coil in methylethylketone (MEK) and dioxane as solvents. The viscosity of MHC-Na and MHC-Cd as a function of the neutralization α has a maximum; its position shifts towards larger α values with increasing dielectric constant.

Molecular weight and molecular weight distribution of 1,4-cis-polyisoprene obtained under various conditions with the system TiCl4Al(C7H15)3☆

Abstract Gel permeation chromatography and accelerated sedimentation have been used to study the way in which the molecular characteristics of 1,4- cis -polyisoprene depend on the polymerization conditions on the catalytic system TiCl 4 Al(C 7 H 15 ) 3 . It is shown that the polymer contains a gel fraction of from 7 to 15% and that changing the polymerization conditions enables the molecular characteristics of the poly-isoprene to be regulated. Satisfactory agreement is reported in the determination of molecular mass and molecular weight distribution by sedimentation and gel permeation chromatography.

Investigation of the viscosity of dilute solutions of mixed polymers

Abstract A study was made of the viscosity of solutions of mixed polymer homologues and of incompatible mixtures of polymers in two groups. For the first group of polymers, as well as for the polymer homologues, there is fulfillment of the law of additivity, while for the second group it was found that there were positive and negative deviations of experimentally obtained viscosity values from the calculated values. The experimental results agree well with a theoretical analysis of the viscosity of the solutions of mixed polymer homologues and of the polymers in the first group. For solutions of mixed polymers in the second group anomalies in the relation of viscosity to the composition of the mixtures are due to the formation of supermolecular structures that have varying stability towards changes in temperature.

Correction of gel chromatograms for instrumental broadening

The Tikhonov regularization method was proposed for correction of gel chromatograms for instrumental broadening. The results obtained in solving the Tung equation by approximation and regularization methods and also in using the Gauss and Pearson distributions as a function of instrumental broadening were compared.

Molecular and hydrodynamic characteristics of an aromatic polysulphone obtained by electrophilic substitution

The hydrodynamic and optical of properties of aromatic polysulphone have been determined. A link between the hydrodynamik constant S0, D0 [η] and the MW of the polymer has been established. From the values of birefringence using known relations the authors have determined the inherent anisotropy of the segment and monomer unit. It is shown that in interpreting the experimental data it is necessary to allow for the finiteness (non-Gaussian nature) of the macromolecular chain.

Molecular characteristics and kinetic polymerization parameters of polypiperylene

Conclusions1.A study has been made of the molecular characteristics of polypiperylenes obtained by polymerization, under various conditions, on catalysts containing various lanthanides.2.The molecular mass of the polymer varies with the time of polymerization, the concentration of the monomer (CM) and the organoaluminum (CAl) component of the catalyst, and the nature of the lanthanide and the solvent. Equations relating CM, CA1, and the molecular mass have been derived.3.The kinetic parameters for piperylene polymerization on lanthanide catalytic systems have been calculated, and it has been shown that the organoaluminum compound is the principal chain transfer agent.

Structure formation in solutions of zinc and calcium salts of the copolymer of styrene and methacrylic acid

Viscosimetric and dynamic birefringence studies were made of the behaviour of Zn and Ca ionomers in DMF and bromoform with DMF additions. It was found that solutions of the zinc salts are molecular solutions, whereas macromolecules of the Ca ionomers form rod-like associates with a high degree of order in solutions.