T. Földes-Berezsnich

Kinetics of copolymerization—I. Kinetic investigation of the polymerization of acrylonitrile in homogeneous phase

Abstract A detailed study was made of the kinetics of initiated homopolymerization of acrylonitrile in dimethylformamide and dimethylsulphoxide at 40–60°. The rate of polymerization was found to be proportional to the (initiator concentration)1/2. The rate of initiation of polymerization was determined by the inhibition method, using three stable free radicals. Trends in the average rate of polymerization were also studied for various initial monomer and solvent concentrations. The overall rate constant (K) was strongly dependent on monomer concentration decreasing with decrease of monomer concentration. It has been shown that the hot radical theory describes accurately, without physical contradiction, the solvent dependence of rate constants of polymerization systems.

Kinetics of copolymerization—II. Kinetic investigation of the polymerization of methyl acrylate in solution☆

Abstract The kinetics of methyl acrylate polymerization initiated by azobisisobutyronitrile were investigated in dimethylformamide at 40–60. The polymerization was 1/2 order with respect to initiator; the rate of initiation was independent of the initial concentration of monomer. The rate and the overall rate constant of polymerization strongly depend on the medium: the overall rate constant decreases with increase of solvent concentration. The solvent dependence of overall rate constant can adequately be described by the hot radical theory.

Kinetics of radical copolymerization—XI. Investigation of the rate of initiation and copolymer composition of the system styrene-butyl acrylate benzene

Abstract The initiation rate constant and the composition of copolymers formed at 50° in St-BA-AIBN-Bz systems of various compositions were investigated. The initiation rate constant was linearly dependent on the composition of monomers (“additive behaviour”). The experimental composition data were evaluated by the η-ξ transformation method and the reactivity ratios determined accordingly are dilution independent values: ρ1 = 0.698 ± 0.033, ρ2 = 0.164 ± 0.017.

Kinetics of radical polymerization—XXXIX Investigation of the polymerizations of butyl acrylate and methyl acrylate in solution

Abstract The kinetics of free radical polymerizations of methyl and butyl acrylate were studied in benzene at 50°. The initiation rate constant determined by the inhibition method was found to be constant over the whole monomer-solvent composition range in both systems. The polymerization rate was investigated as a function of initiator and monomer concentrations. In accordance with theory, an initiator order of 0.5 was obtained for both systems; monomer orders > 1 were found. This solvent effect could not be explained either in terms of the diffusion theory or by the theory of EDA complexes; complete agreement was found between experimental results and the theory of hot radicals.

Kinetics of free radical polymerization—XXXI. Solvent effect on the polymerization rate of ethyl acrylate

Abstract The free radical polymerization of ethyl acrylate was investigated in benzene and dimethyl formamide solutions at 50°. The effects of initiator and monomer concentration were studied over a wide range. The overall rate of polymerization was proportional to (initiator concentration) 1 2 but not to the concentration of the monomer. We attempted to interpret this solvent effect on the basis of (i) the diffusion theory, (ii) the theory of charge transfer complexes and (iii) the theory of hot radicals. Our experimental results could only be explained quantitatively in terms of hot radicals.

Kinetics of radical polymerization—XLIII. Investigation of the polymerization of methyl acrylate in solution by the rotating sector method

Abstract The solvent effect on the chain propagation (k2) and chain termination (k4) rate constants was studied for the polymerization of MA in benzene at 50°. Absolute values of the rate constants were determined from the classical polymerizations published earlier and from rotating sector measurements. The value of k4 was found constant within the limits of experimental error, while k2 greatly depends on the monomer concentration, its variation can be quantitatively described in terms of the hot radical theory.

Kinetics of radical polymerization—XLII. Investigation of styrene styrene polymerization in solution by the rotating sector method

Abstract A brief report is given of the method of intermittent illumination and of the rotating sector polymerization instrument built in our laboratory. The solvent dependence of chain propagation and termination rate constants was investigated for the polymerization system styrene-benzene at 50°. The observed solvent dependence was found to be caused by the chain propagation step, in accordance with the hot radical theory.

Kinetics of radical copolymerization—VIII Investigation of the effect of molecular inhibitors in copolymerization—1. Bulk copolymerization

Abstract The stoichiometry of the inhibition reaction was studied in AN-MA, AN-St and MA-St copolymerization systems in the presence of nitroso-type molecular inhibitors. According to our experiments, the stoichiometric coefficient of the inhibitor depends on the initial composition of monomers. The hot radical theory, elaborated for the inhibition of polymerization, was extended to the inhibited copolymerization; this theory made it possible to explain and to describe quantitatively the variation of experimental μ value with the initial monomer composition.

Kinetics of radical polymerization—XL. Investigation of the effect of molecule inhibitors in polymerization in solution

Abstract The effect of monomer concentration on the stoichiometric coefficients of nitroso-type molecule-inhibitors was studied for solution polymerizations of AN, MA and St (the solvents were DMF and Bz). The anomalies found in the dependence on the monomer concentration was interpreted; the μ = f ( x mon ) relationship was quantitatively described with the inhibition parameters determined from our experimental results.

Kinetics of copolymerization—VI Investigation of copolymer composition in the system acrylonitrile—methyl acrylate-dimethylformamide

Abstract The compositions of copolymers formed under different copolymerization conditions were studied for the system acrylonitrile-methyl acrylate-dimethylformamide at 50°C. The relationship between the compositions of the feed and the copolymer cannot be described with sufficient accuracy either by the classical copolymerization equation or by the equation derived from the penultimate model. The systematic deviations observed on application of the classical composition equation can be qualitatively well interpreted in terms of the hot radical theory.