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Journal ArticleDOI

Redox polymerization of acrylonitrile. Kinetics of the reaction initiated by systems based on cyanoacetic acid/Mn(III) complexes in dimethylsulphoxide

01 Jan 1982-European Polymer Journal (Pergamon)-Vol. 18, Iss: 6, pp 501-505
Abstract: The kinetics of polymerization of acrylonitrile initiated by the redox systems cyanoacetic acid/Mn(OAc) 3 and cyanoacetic acid/tris(benzoylacetonato)manganese(III) in dimethylsulphoxide as solvent have been investigated over the range 20–35°. The kinetics of oxidation are consistent with the formation of intermediate complexes between the reactants, followed by electron transfer. Manganous ions inhibit the reaction by competitive complexation. The primary radicals are very efficient as initiators of polymerization which is terminated by mutual interaction of macroradicals. Mechanisms have been proposed to explain the kinetics; rate and equilibrium constants have been evaluated.
Topics: Cyanoacetic acid (62%), Polymerization (55%), Acrylonitrile (54%), Radical (52%), Redox (52%)
Citations
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Abstract: The photodegradation of thin films of poly(para-tert-butylstyrene) with 265 nm radiation in the presence of oxygen, and as a function of irradiation time, has been studied using fluorescence, Fourier transform-infrared spectroscopy, and ultraviolet-visible spectroscopy. The influence of phthalate and terephthalate plasticizers on photo-oxidative degradation was also investigated. Blending with phthalate plasticizers was found to cause a higher efficiency of degradation than that obtained for doping with terephthalate plasticizers. The intensity of absorption was also found to increase with time of irradiation and in the intensity of a new absorption band at longer wavelength, thus indicating a possibility of photodegradation of polymer films. The analysis of the Fourier transform-infrared spectra of the irradiated and non-irradiated samples showed an increase in the intensities of the carbonyl and hydroxyl regions of the Fourier transform-infrared spectra providing evidence for the photodegradation as well as the photo-oxidation of polymeric chains. The increase in the analyzed ranges is attributed to the formation of alcohols, aliphatic ketones and to the increase in the number of polyene structures that resulted from hydrogen abstraction during photodegradation reactions.

11 citations


References
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Journal ArticleDOI
Abstract: Weight-average molecular weights and intrinsic viscosities in dimethyl formamide at 25° have been measured for four unfractionated low-conversion acrylonitrile polymers covering the molecular weight range 30 to 250 thousand. The results follow the equation:

122 citations



Journal ArticleDOI
Abstract: Kinetics of vinyl polymerisation initiated by the redox system malonic acid/Mn3⊕ have been investigated in the temperature range of 5-15°C in sulphuric acid and perchloric acid media for acrylonitrile and methyl methacrylate. A mechanism involving the formation of a complex between Mn3⊕ and malonic acid whose decomposition yields the initiating free radical with the polymerisation being terminated by mutual interaction of growing radicals has been suggested. Es wurde die Reaktionskinetik der durch das Redoxsystem Malonsaure/Mn3⊕ initiierten Vinylpolymerisation von Acrylnitril und Methylmethacrylat im schwefelsauren und perchlorsauren Medium im Temperaturbereich von 5-15°C untersucht. Es wird ein Mechanismus vorgeschlagen, welcher die Bildung eines Komplexes zwischen Mn3⊕ und Malonsaure vorsieht. In dem vorgeschlagenen Mechanismus wird das Startradikal durch Zerfall des Komplexes gebildet, und die Abbruchreaktion erfolgt durch eine Radikalkettenabbruchsreaktion der wachsenden Polymerketten.

28 citations


Journal ArticleDOI
Abstract: SELECTIVE FREE-RADICAL INITIATION Selective initiation of free-radical polymerization is, as far as I am aware, a novel phenomenon Conventional initiators such as benzoyl peroxide and azo-bis-isobutyronitrile, which produce active radicals, are not significantly discriminating in their behaviour towards different monomers, provided these can be polymerized by a radical mechanism; indeed the rate of initiation by azo-bis-isobutyronitrile at a given concentration is essentially the same for a number of common monomers12 Recent work3 has revealed the existence of a type of initiator which is strongly selective, the rate of initiation apparently depending on the electron-accepting properties of the monomer Our interest in selective initiation of free-radical polymerization arose during studies of initiation by chelate derivatives of metals, which will now be described briefly Three groups of workers have shown that certain metal acetylacetonates can act as sources of initiating radicals4-6 Both Kastning et al5 and ourselves6 have pointed out the relatively high activity possessed by manganic acetylacetonate Mn"(acac)a compared to the simple chelates of other metals At 80°C the rate of polymerization w of bulk methyl methacrylate is given as a function of chelate concentration by the equation

10 citations


Journal ArticleDOI
Abstract: Manganese(III) acetylacetonate, in the presence of a suitable electron donor such as dimethyl sulphoxide, is an active, selective, initiator of free-radical polymerization at 25°, the order for the monomers studied being acrylonitrile > methyl methacrylate > styrene: suggested mechanisms for selective and nonselective components of the reaction involve ligand displacement.

9 citations