V. P. Zakharov

Enhancement of the activity of the titanium catalyst for isoprene polymerization by improving the step of active site formation

Commercial microheterogeneous titanium catalyst in the step of its preliminary formation was subjected to hydrodynamic action by circulation in a tubular diffuser-confuser apparatus. As a result of such treatment, the Mooney viscosity of the high-molecular-weight polyisoprene prepared in the presence of this catalyst becomes more stable.

Improvement of the neodymium catalyst preparation step in isoprene rubber production

The results of pilot tests of a tubular reactor of the diffuser-confuser type in modification of neodymium chloride isopropanol complex in turbulent flows were presented. The new procedure leads to reduced catalyst consumption, as well as to increased average molecular weights and narrowed molecular weight distribution of cis-1,4-polyisoprene.

Enhancement of the activity of a neodymium catalyst for the synthesis of stereoregular polyisoprene

A new ligand based on two pyrazole cycles linked with each other was synthesized. Its interaction with Cu(II), Ni(II), Co(II), Mn(II), Cr(III), Zn(II), and Cd(II) cations in ethanol was studied by the spectrophotometric method.

Kinetic inhomogeneity of titanium- and neodymium-based catalysts for the production of cis-1,4-polyisoprene

The kinetic inhomogeneity of polysite titanium- and neodymium-based catalysts for the industrial production of cis-1,4-polyisoprene significant studied. The titanium- and neodymium-based catalysts are characterized by the presence of two and three types of active sites, respectively. Modification, including hydrodynamic treatment, of the titanium and neodymium catalyst makes it possible to prepare monosite systems with the same kinetic activity.

Kinetic inhomogeneity of copolymerization sites of butadiene and isoprene on titanium catalyst

Copolymerization of butadiene and isoprene on the titanium catalyst proceeds on three types of active sites, and this correspond to the standard set of homopolymerization of isoprene. Sites responsible for the preparation of low-molecular-mass fractions of macromolecules are more active in the copolymerization as compared with homopolymerization of butadiene and isoprene. Change in the hydrodynamic regime in the reaction region is accompanied by an increase in the copolymerization rate due to an increase in the over-all concentration of active sites but it does not affect the typical set of growth sites of macromolecules. Distribution curve of active sites with respect to their reactivity is shifted to the high-molecular-mass region with increasing average weight molecular mass with decreasing average number molecular mass when the corresponding molecular-mass distribution becomes broader.

Kinetics of the enzymatic hydrolysis of chitosan films

The kinetics of the enzymatic hydrolysis of chitosan film samples under the action of the enzyme hyaluronidase was studied. It was found that, although a monolithic film sample was subjected to hydrolysis, the enzymolysis of chitosan in this case obeyed the same laws as the enzymatic hydrolysis of chitosan in solution at small substrate concentrations.

Low-toxic nitrogen-containing antioxidant for polyvinyl chloride

The kinetics of thermal oxidative dehydrochlorination of rigid and plasticized polyvinyl chloride in the presence of 5-hydroxy-6-methyluracil was studied. 5-Hydroxy-6-methyluracil shows high antioxidant performance, inhibiting the polymer degradation. This additive significantly decelerates the accumulation of hydroperoxides in the course of oxidation of the polyvinyl chloride plasticizer, dioctyl phthalate, which ultimately leads to considerable deceleration of the degradation of the plasticized polymer.

The role of low-molecular-mass electrolyte drug substances in the modification of the chitosan matrix

The effect of antibiotics of the aminoglycoside and cephalosporin series on the properties of chitosan films formed from acetic acid solutions is studied. It is shown that the introduction of the indicated substances substantially affects the conformational state of chitosan acetate and its supramolecular structure. The modification of chitosan by drug substances, accompanied by loss in solubility of chitosan films in water, leads to a decrease in the rate of desorption of antibiotics from the polymer matrix.

Kinetic nonuniformity of a titanium catalyst in the polymerization of butadiene: Effect of intensifying stirring of the reaction mixture

Intensification of turbulent stirring of the reaction mixture in the course of butadiene polymerization on a titanium catalyst promotes a successive increase in the rate of reaction with increasing polymer content. Independent of the viscosity of the reaction mixture, the concentration of active centers forming the low-molecular-mass fraction of polybutadiene decreases and the molecular mass distribution narrows. The reactivity distribution of active centers is determined by the hydrodynamic effect, and it does not depend on the increasing viscosity of the reaction mixture. This suggests an insignificant influence of viscosity and, hence, diffusion limitations on the distribution of active centers of polymerization over the probability of chain propagation.

Synthesis of antiagglomeration agent based on calcium stearate for synthetic rubbers in tubular apparatus

Formation of an antiagglomeration agent for synthetic rubbers, based on an aqueous suspension of calcium stearate, by the reaction a highly concentrated solution of calcium chloride (up to 40 wt %) and a dilute solution of potassium stearate (up to 5 wt %) in a small tubular apparatus of diffuser-confuser design was studied.