N. V. Yablokova

Styrene polymerization on mineral filler surfaces, modified with organosilicon peroxides☆

Styrene polymerization on filler surfaces modified with organosilicon peroxides has been studied. It was shown that the amount of initiator grafted to the surface depends on the nature of the peroxide and of the filler. The kinetic parameters of breakdown of the initiators, grafted to the surface and the features of styrene polymerization on modified fillers have been established. It was shown that vinyltri(tert-butylreroxy) silane is capable of ensuring the formation of polystyrene compositions with a grafted polymer, without previous modification of the filler surface. The effect of surface modification of the filler on the properties of polystryrene samples, filled with Aerosil and Al2O3 was studied.

Emulsion copolymerization of butyl acrylate with methacrylic acid

Abstract The kinetic laws of emulsion copolymerization of butyl acrylate with methacrylic acid, iniated by ammonium persulphate in the presence of sodium lauryl sulphonate as emulsifier and ammonium sulphate as salting-out agent are studied. Data are obtained on the activation parameters of the process, the copolymerization mechanism, and the relative activities of the monomers.

Initiating radical polymerization of vinyl monomers by silicon peroxides

Abstract The initiating ability of organosilicon peroxides, Me 4-m Si ( OOCMe 3 ) m where m = 1−3, for polymerization of vinyl monomers has been quantitatively characterized. Complex formation between monomers and Lewis acids has been found to activate the polymerization process. The activation effect is observed for a ratio [Lewis acid]/[monomer] of 0.003 to 0.02. The complex formation parameters (equilibrium constant and complex composition) have been determined by PMR, thermochemical and cryoscopic methods. Organosilicon peroxides have been found to influence the composition of copolymers; polyfunctional peroxides can be used to prepare block copolymers.

On the mechanism of initiation of butyl methacrylate polymerization by silicon monoperoxide

Kinetic parameters have been determined for butyl methacrylate polymerization initiated by Me3SiOOCMe3 in the range 353–373 K. It has been proved by PMR analysis that the rate of formation of a donor-acceptor complex of monomer with silicon monoperoxide, decomposing to radicals, is higher than for the pure peroxide. Catalytic amounts of Lewis acids activate decomposition of Me3SiOOCM3. As regards their influence on the polymerization rate Lewis acids may be placed in the following order: Bu3SnCl<R2SnCl2, where R=Me, Et, n-Pr, n-BU, <ZnCl2⪡SnCl4. An increase in the rate of polymerization initiated by Me3SiOOCMe3 in presence of Lewis acids is accompanied by a reduction in the activation energy of the process from 74·6 to 46·9 kJ/mole, and by a reduction in MW of the polymer. The polymerization rate is lower in the case of a marked excess of Lewis acid with respect to the peroxide. The activation effect stems from an increase in the rate of initiation of polymerization owing to the formation of a complex between components of the initiating system.

Effect of inhibiting additives on the emulsion (co)polymerization of butyl acrylate and methacrylic acid

Abstract The effect of the inhibiting additives, hydroquinone and 1,4-benzoquinone, on the kinetics and formation of particles in emulsion (co)polymerization of butyl acrylate with methyacrylic acid has been studied. The order for emulsifier was reversed. An explanation for this is offered. It is shown that the presence of hydroquinone (5–10% in relation to the initiator) favourably affects the kinetic parameters of the copolymerization process. Additions of benzoquinone worsen the characteristics of the copolymer (increase its homopolymer content).

Kinetics and mechanism of high-temperature decomposition of di-methyl-di (tert-butyl-peroxy) silane

Kinetic parameters and rate constants for initiation reaction during thermal decomposition of di-methyl-di (tert-bytylperoxy) silane in tetravalerate-pentaerythrol solution have been determined at temperatures ranging from 170 to 220°C. It has been established that tert-butyl hydroperoxide, the product of homolytic peroxysilane decomposition, takes part in the initiation reaction.AbstractИзучены кинетические закономерности и определены константы скорости инициирования при термическом разложении ди-метил-ди (трет-бутил-перокси) силана в растворе тетравалерата пентаэритрита при 170–220°C. Установлено, что в реакции инициирования принимает участие гидропероксид третбутила, являющийся продуктом гомолитического разложения пероксисилана.

Modelling the process of synthesis of low molecular mass polyacrylic acid

A mathematical model of solution polymerization of acrylic acid initiated by the system H2O2Cu2+ accompanied by the formation of low molecular mass polyacrylic acid is considered. It has been established that termination of the polymerization chain comes about in the main on the Cu2+ ions. Increase in the concentration of H2O2 and Cu2+ promotes a fall in the MM of polyacrylic acid. Cu2+ ions are both a component of the initiating system and a regulator of the MM of polyacrylic acid. The mathematical model of the process considered helps in the selection of the requisite concentrations of the starting reagents and the conditions of conducting the experiment for obtaining polyacrylic acid of specified MM.

Polymerization of methacrylic esters initiated by organosilicon peroxides in the presence of sulfuryl chloride

The kinetic parameters for the polymerization of butyl methacrylate initiated by the (CH3)4−nSi[OOC(CH3]n-SO2Cl2 system, where n = 1−3 are determined. It is established that polymerization obeys the main laws of a radical process, and the acrylic monomer polymerization activation effect is associated with the formation of unstable peroxide esters, which are derivatives of chlorosulphonic acid, which generate radicals on decomposition. The composition curves for the copolymer of acrylonitrile with styrene, obtained by using this system, also confirm the radical nature of the process. In the given system the SO2Cl2 can be considered as a complex modifier: a chain transfer agent, a co-catalyst, and a complexing agent.