Mathematical modeling of 1,3-butadiene polymerization over a neodymium-based catalyst in a batch reactor with account taken of the multisite nature of the catalyst and chain transfer to the polymer

A mathematical model for a batch polymerization process under the effect of a neodymium versatate-diisobutylaluminum hydride-hexachloro-p-xylene catalytic system is developed that takes into account its polycentric nature and chain transfer to the polymer. The mechanism of 1,3-butadiene polymerization in the presence of the catalytic system under investigation is proposed. It is assumed that butadiene polymerization occurs at two types of active sites with the transition of the centers with higher activity to the centers with lower activity. The constructed mathematical model adequately describes the experimental data, which confirms the proposed mechanism of the process.     

Use of basic zirconium carbonates for the synthesis of refractory materials

Conclusions The technology for the production of a basic zirconium carbonate of various grades has been developed. The processes occurring during the thermal decomposition have been studied and it is shown that zirconium carbonate can be used as good raw material for the synthesis of cubic and tetragonal solid solutions.A method has been developed for obtaining cubic and tetragonal solutions which makes it possible to lower the temperature of the synthesis by 800–1000°C from the present temperature.Translated from Ogneupory, No. 5, pp. 47–49, May, 1980.