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1.
The polymerization of methyl methacrylate was studied using the peroxydiphosphate and tartaric acid redox system as the initiator. The rate of polymerization increases with increasing peroxydiphosphate concentration and the initiator exponent was computed to be 0.5. The rate of polymerization increases with increasing monomer concentration and the monomer exponent was computed to be unity. The reaction was carried out at three different temperatures, and the overall activation energy was computed to be 3.80 kcal/mol. The effect of certain surfactants on the rate of polymerization has been investigated and a suitable kinetic scheme has been proposed. 相似文献
2.
R. K. Samal P. C. Dash B. Mishra G. V. Suryanarayana D. P. Das M. C. Nayak 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5):805-819
Polymerization of acrylonitrile initiated by the Cr6+/thioacetamide redox system was studied in nitrogen atmosphere in the temperature range 35–45°C. The rate of polymerization and the rate of Cr6+ ion disappearance were measured. The effect of certain water-miscible organic solvents, neutral electrolytes, and complexing agents on the rate of polymerization was investigated. Chromic acid alone did not initiate the polymerization under deaerated and undeaerated conditions. Depending on the results obtained, a suitable kinetic scheme was proposed and various rate parameters were evaluated. 相似文献
3.
Abstract The polymerization of vinyl monomers initiated by dimethylhydroxylamine hydrochloride (DHA)-titanous(III) chloride redox system has been studied in water under a nitrogen atmosphere. In the polymerization of methyl methyacrylate (MMA) initiated by the above system, the rate of polymerization has been found to be proportional to [DHA]0.5 for DHA concentrations of less than 2.06 × 10?3 mole/liter, whereas at higher concentrations the rate tends to fall rapidly. The rate has also been found to be proportional to [Ti(m)] 0.58 and to [MMA] 1.0. The maximum rate of polymerization has been observed at a 1:1 molar ratio of DHA to Ti(III). The polymerization proceeded via a radical mechanism. The overall activation energy was estimated as 5.5 kcal/mole. It has been suggested that the reduction of dimethylhydroxylamine by titanous(III) chloride yields the dimethylamino radical, which initiates vinyl polymerization. An examination of the initiating capacity of the initiator system for the polymerization of some vinyl monomers has also been made. 相似文献
4.
P. C. Dash D. P. Das B. K. Mohanty R. K. Samal M. C. Nayak 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):1357-1370
Kinetics of polymerization of acrylonitrile initiated by the redox system V5+ascorbic acid were investigated in aqueous sulfuric acid in the temperature range of 35–50°C, and the rates of polymerization, of V5+/disappearance, etc. were measured. From the result it was concluded that the polymerization reaction is initiated by an organic free radical arising from the V5+ - ascorbic acid complex formation followed by subsequent decomposition and terminated by V5+ions. A suitable kinetic scheme was proposed and the various rate parameters were evaluated. 相似文献
5.
Kinetics of vinyl polymerization initiated by the redox system thiourea-Mn3+ were investigated in the temperature range 30–40°C in sulfuric acid, and the rates of polymerization Rp and disappearance of Mn3+ have been measured. The effect of certain water-miscible organic solvents and anionic surfactant on the rates of polymerization was investigated. A mechanism involving the formation of a complex between Mn3+ and thiourea whose decomposition yields the initiating free radical with the polymerization terminated by mutual intraction of growing radicals is suggested. 相似文献
6.
Hirofusa Shirai Yasuharu Nagatomo Yoshiaki Inaki Kiichi Takemoto 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5):935-947
The polymerization of acrylonitrile initiated with the imidazole-copper (II) complexes was studied in dimethylsulfoxide solution. The ability of the complexes to initiate polymerization seems to depend on their anion. 2-Substituted imidazole-copper (II) complexes of the type, CuL4X2 (L = imidazole as ligand and X = anion), were also found to initiate vinyl polymerization. From the data of electronic spectra in dimethylsulfoxide solution, the initiation mechanism is discussed in terms of the formation of the active species by the interaction of the complex with monomer molecules. 相似文献
7.
Abstract The binary system of tetramethyl tetrazene (TMT) and Co(II) chloride was used as initiator of acrylonitrile (AN) in dimethylformamide. The initial rate of polymerization (Rp) was found to be expressed by Rp = k[TMT]0.62[Co(II) chloride]0.57 [AN]2.00 The polymerization was confirmed to proceed via a radical mechanism. The over-all activation energy for the polymerization was estimated as 15.1 kcal/mole. On the basis of these results and the product analysis of the reaction between the catalyst components in the absence of monomer, the initiation mechanism of the polymerization is discussed. 相似文献
8.
R. K. Samal G. V. Suryanarayan G. Panda D. P. Das M. C. Nayak 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7-8):1087-1098
Abstract Kinetics of vinyl polymerization of acrylonitrile initiated by the redox system Mn(III)/ethane thiol were investigated in aqueous sulfuric acid in the temperature range of 30-45°C. The rate of polymerization, rate of manganic ion disappearance, etc. were measured. The effect of certain water-miscible organic solvents, neutral electrolytes, and organic nitrogen compounds on the rate has been investigated. A mechanism involving the formation of a complex between Mn(III) and the thiol, whose decomposition yields the initiating free radical with the polymerization being terminated by mutual combination of the growing radicals, has been suggested. 相似文献
9.
The application of polymers at ever-increasing temperatures has given impetus to research on the chemistry of thermal decomposition. In recent years polymers have been used for a variety of high-temperature applications, such as cooking vessels, motor insulation, and re-entry vehicle heat shields. Interest in chemistry of decomposition has been found in such industries as tobacco and grinding-wheels. Because of the vast number of polymers that are available and the variety of applications thousands of papers have appeared in the literature. Rather than give a complete review the purpose of this paper is to give a brief survey of topics that have been emphasized in the author's research, namely kinetics, mechanisms, and gaseous decomposition products at elevated temperatures. 相似文献
10.
The kinetics of the polymerization of acrylonitrile initiated by the redox system peroxydisulfate-cyclohexanol catalyzed by silver ion has been studied. The rate of polymerization was found to be directly proportional to the first power of monomer concentration and the square roots of peroxydisulfate, cyclohexanol, and silver ion concentrations. The effect of temperature has been investigated in the range of 35 to 60°C and the overall activation energy was found to be 4.6 kcal/mol from the Arrhenius plot. A plausible kinetic scheme has been proposed to account for the observations. 相似文献
11.
The polymerization of methyl methacrylate initiated by the vanadium acetylacetonate complex was investigated under a nitrogen atmosphere at 50°C. The effect of concentration of monomer, complex, acid, dioxane, inhibitor, and the effect of temperature on the rate of polymerization were studied. The rate of polymerization was found to increase upon increasing the concentrations of the monomer, the initiator, and the acid. The overall activation energy has been computed from the Arrhenius plot and a suitable kinetic scheme has been proposed. 相似文献
12.
The kinetics of the aqueous polymerization of acrylonitrile initiated by the chromic acid-1-propanol redox system was investigated under a nitrogen atmosphere. The rates of polymerization and the disappearance of Cr(VI) were measured. Chromic acid alone did not initiate the polymerization under deaerated and undeaerated conditions. Water-miscible organic solvents and neutral salts depress both the rate and the conversion. On the basis of the experimental observations of the dependence of the rate of polymerization Rp and the rate of disappearance of Cr(VI)-Rm on various variables, a suitable kinetic scheme was proposed and various rate and energy parameters evaluated. 相似文献
13.
Keiichi Kimura Akira Matsui Yoshiaki Inaki Kiichi Takemoto 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8):1231-1241
Polymerization of acrylonitrile initiated by triazole-copper(II) complexes was studied in dimethylsulfoxide solution. It was found that the polymerization proceeds by a free radical mechanism; however, the complexes can hardly homopolymerize methyl methacrylate and styrene. Ability of the complexes to initiate polymerization seems to depend on the substituents of triazole, the sort of solvents, and the counterions of copper(n) salts. From the data of visible spectroscopy and the spin trapping, the initiation mechanism was discussed in terms of reduction of copper(II) followed by forming active species. 相似文献
14.
Polymerization of Acrylonitrile: Kinetics of the Reaction Initiated by the Redox System Mn3/Mannitol
R. K. Samal G. V. Suryanarayan G. Panda N. K. Dash D. P. Das M. C. Nayak 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5):791-800
Polymerization of acrylonitrile initiated by the redox system Mn3+/mannitol has been investigated in aqueous sulfuric acid in the temperature range 35–50°C. The rate of polymerization Rp and the rate of disappearance of Mn+3 (?RM) were measured. The effect of certain water-miscible organic solvents, inorganic salts and complexing agents on the rate of polymerization have been investigated. Based on the experimental results, a suitable reaction mechanism is suggested involving the formation of complex between Mn3+ and the hydroxyl group of the substrate molecule, whose decomposition yields the initiating free radical; the polymer chain is terminated by the mutual combination of growing chains. 相似文献
15.
The vinyl polymerization of acrylonitrile initiated by the redox system Mn3+-cyclohexanol was investigated in aqueous sulfuric acid in the temperature range of 30–45° C. The rate of polymerization Rp and the rate of Mn3+ ion disappearance were measured. The effects of certain water-miscible organic solvents and certain anionic, cationic, and nonionic surfactants on the rate of polymerization were investigated. Based on the results obtained, a suitable reaction mechanism involving the formation of a complex between Mn3+ and the alcohol, whose decomposition yields the initiating free radical with the polymer chain being terminated by the mutual combination of growing chains is suggested. 相似文献
16.
Abstract Methyl methacrylate was found to be polymerized by the system polyacrylonitrile-water-cupric ion without any added initiator. Addition of carbon tetrachloride to this system greatly increased the polymerization rate. Acrylonitrile and styrene did not polymerize in this system. The kinetic behavior of polymerization was the same as the system consisting'of cellulose or nylon instead of polyacrylonitrile. When the flaky polyacrylo-nitrile was swelled or dissolved by the solvent DMF, the conversion and the degree of polymerization of the poly-methyl methacrylate formed decreased markedly. Commercial acrylic fiber also initiated polymerization but the activity was lower than with flaky polyacrylonitrile, even after steam treatment, because of the poor permeability of monomer into the fiber. 相似文献
17.
Abstract A number of monomers have been polymerized in the presence of catalytic and higher concentrations of SO2. The addition of t-butyl hydroperoxide greatly accelerates the rate of polymerization. The use of 35SO2 indicates that at catalytic concentrations of SO2 (10?2 mole/liter), only one or two molecules of SO2 are incorporated in the chain, but, at high SO2 concentrations, copolymerization of SO2 with vinyl monomers occurs. 相似文献
18.
Tatsuro Ouchi Kazuhiro Nomoto Yoshifumi Hosaka Minoru Imoto Tadao Nakaya Tsutomu Iwamoto 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(6-7):859-866
Abstract Three kinds of betaine-type polymers, which are macromolecular amphoteric electrolytes, were found to be able to polymerize vinyl monomers in aqueous solution through a radical mechanism without any further initiator. Betain-type polymers form hydrophobic areas (HA) in water. Vinyl polymerization commenced in the HA. The effect of the pH of the aqueous solution on polymerization was investigated. 相似文献
19.
Homogeneous polymerization of methacrylamide initiated by the ceric ammonium sulfate-citric acid (CA) redox pair has been investigated and reported at 35 ± 0.2°C under nitrogen atmosphere. The initiation was caused by the free radical generated by the decomposition of the complex formed between ceric ion and citric acid. The rate of monomer disappearance was found to be proportional to [CA]0.4, [Ce0.4+]0.65, and [Monomer]1 The rate of ceric ion disappearance was directly proportional to the ceric ion concentration but independent of the monomer concentration. The initial rate was independent of [H2SO4]. The activation energy of the system was found to be 21.4 kJ/mol. 相似文献