Inhibitors Of Radical Polymerization Research Articles

Resonant electron capture by quercetin derivatives

According to available experimental data, the formation of long-lived (∼10−5 s) negative molecular ions (NMIs) due to resonant electron capture (REC) by polyatomic molecules is observed experimentally with the proviso that their electron affinity (EA) is on the order of several tenths of electronvolt or above. Such compounds are characterized by large NMI formation cross sections. High ability to effectively capture thermal electrons correlates with their ability to capture free radicals, in particular, to act as inhibitors of radical polymerization [1]. It is likely that these compounds will exhibit antioxidant activity as well. It is therefore of interest to use the REC technique for studying antioxidant compounds, of which the bioflavonoid quercetin (QU) (1) (Fig. 1) and its derivatives are prominent representatives [2, 3].

Safe method for synthesis of methoxy-NNO-azoxyethene

Safe method for synthesis of methoxy-NNO-azoxyethene by pyrolysis of 1,1-di(methoxy-NNO-azoxy) ethane in high yield was developed. The method is based on use of dibutyl phthalate as phlegmatizer and polyphenols as inhibitors of radical polymerization.

Mechanism of synergistic action of binary mixtures of antioxidants reacting with alkyl and peroxyl radicals

1. The synergism shown by mixtures of alkyl radical acceptors and inhibitors interacting with peroxyl radicals is due to the formation of donor-acceptor complexes between them, these complexes having high activities in the reaction with the alkyl radicals. 2. Complexes of chloranil with aromatic amines and phenols are inhibitors of radical polymerization. An estimate has been made of the reactivity of the complexes with respect to the alkyl radicals of methyl methacrylate. 3. Mixtures of a nitroxyl radical with electron donors-N,N,N′,N′-tetraethyl-p-phenylenediamine, N-methylpyrrolidone, and N,N-dimethylformamide — manifest synergism in the oxidation of 1-nonene. 4. Equilibrium constants and extinction coefficients have been measured for charge transfer complexes of chloranil withα-naphthylamine and diphenylamine in 1-nonene.

Asphalts as inhibitors of radical polymerization

AbstractThe results of investigations concerning the effect of asphalts on radical polymerization of a monomer for model systems composed of styrene and two petroleum asphalts originated from two different crude oils: low sulphur nonparaffinic crude oil and medium sulphur paraffinic crude oil. Based on determination of styrene conversion in the radical polymerization process in the presence of asphalts, it was found that both asphalts act as inhibitors of this reaction. The inhibiting effect of asphalts is weakened by using higher temperatures and prolongation of polymerization time or application of greater initiator rates. On the basis of the analysis of group and elementary chemical composition of both asphalts as well as electron paramagnetic resonance, it was found that the inhibiting effect to radical polymerization is caused mainly by the presence of structures which are stable free radicals in character. The probability of inhibiting effect by sulphur compounds present in asphalts is also discussed.

Radiation chemical method of exciting thiacyclanes as inhibitors of radical polymerization

The inhibiting activity of the following compounds in the polymerization of methyl methacylate during γ-irradiation has been studied: elemental sulphur, 3,6-dimethyl-1,4,5-trithiocycloheptane (TCH), 1,3,5,7-tetramethyl-2,4,6,8-tetrathioadamantane (TTA) and 1,3,5,7-tetramethyl-2,4,6,8,9,10-hexathioadamantane (HTA). It is shown that γ-irradiation causes an increase in the activity of the inhibiting additions which is connected with radiolysis of the sulphur containing compounds.