摘要:

Homopolymerization of 1, 3-divinylimidazolid-2-one and 1, 3-divinylhexahydropyrimid-2-one produces cross-linked polymers. 1, 3-Diphenyl-1, 3-divinylurea (DPDVU) and 1, 3-dimethyl-1, 3-divinylurea (DMDVU) could not be polymerized. 1-Ethyl-3-vinylimidazolid-2-one yields a soluble linear polymer. All of the N, N′-divinylureas have a strong absorption band in the UV region of the spectrum, which is good evidence for conjugation of the electron pairs on the nitrogen atom with the π-electrons of the vinyl and carbonyl double bond. Further support for conjugation is obtained from NMR and IR spectroscopy. Such conjugation would tend to favor intermolecular propagation rather than the cyclopolymerization mechanism. The inability of DPDVU to polymerize is explained by the fact that addition of a radical to this monomer produces a resonance stabilized free radical. The failure of theintermolecular propagation reaction with DMDVU is attributed to steric hinderance. Rapid hydrolysis of the N-vinyl group in these compounds takes place in aqueous solution, yielding acetaldehyde and the corresponding urea.

ISSN:0022-233X    

DOI:10.1080/10601327508056925

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Divinyl phenylphosphonate and divinyl methylphosphonate have been synthesized using modifications of the method of Gefter and Kabachnik. In contrast to the results reported by these authors, it has been possible to obtain soluble, fusible, linear polymers (cyclopolymers) from both monomers by polymerization in dilute solution.

ISSN:0022-233X    

DOI:10.1080/10601327508056926

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

In order to elucidate the initiation reaction of the photopolymerization with iron(III)-amine-carbon tetrachloride systems, the photochemical reaction process among iron(III), amine, and carbon tetrachloride in methanol solution was followed at 0°C by UV spectroscopy as for iron(III) ion. The rate constants of both the reduction of iron (III) under irradiation with light and the oxidation of iron(II) in the dark were measured, and were related to the rates of photopolymerization of methyl methacrylate. Kinetic study on the photopolymerization of methyl methacrylate with iron(III)-triethylenetetramine-carbon tetrachloride system was made in parallel in methanol solution at 0°C. The initiation mechanism of the photopolymerization was postulated.

ISSN:0022-233X    

DOI:10.1080/10601327508056927

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The kinetics of polymerization of acrylonitrile by the redox system V5+-propane-1, 2-diol in aqueous sulfuric acid at 40 to 50°C were studied. The rate of polymerization, V5+disappearance, and chain lengths of polyacrylonitrile were measured. The kinetics are consistent with the formation of an intermediate complex between the diol and the oxidant whose decomposition leads to the initiating radical. A suitable kinetic scheme has been proposed and the various rate and energy parameters were evaluated.

ISSN:0022-233X    

DOI:10.1080/10601327508056928

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The initiation mechanism of spontaneous alternating copolymerizations of styrene (St) and some electron-accepting monomers such as methyl methacrylate (MMA), methyl acrylate (MA), methacrylonitrile (MAN), and acrylonitrile (AN) in the presence of ZnCl2was studied by the spin trapping technique, in which 2-methyl-2-nitrosopropane (BNO) was used as a spin trapping reagent. When this technique was applied to the alternating copolymerization systems of St-MMA-ZnCl2, St-MA-ZnCl2, and St-MAN-ZnCl2, the 2-phenylvinyl radical (·CH˭CH‒C6H5) was trapped as nitroxide. The structure of this nitroxide, which showed a large coupling constant (19∼20 G) by β-hydrogen, was confirmed by comparison with the result of authentic experiment Accordingly it was concluded that this nitroxide was formed through proton migration from the St cation radical to the acceptor monomer anion radical in the charge- or electron-transfer complex, followed by reaction with BNO.

ISSN:0022-233X    

DOI:10.1080/10601327508056929

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/10601327508056930

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Investigations were made which show that the change in the dynamics of polymerization and in molecular weight of the polymer under an electric field is connected with the redistribution of the ions growing macromolecules and counterions. Analysis of the equations obtained showed that the field can either increase or decrease the rate of the process. The effect's trend and magnitude depend on the ratio of the mobilities of macroions and counterions, degree of dissociation of active centers, and the ratio of rate constants of free ions and ion pairs. An analysis of literature data relevant to polymerization under an electric field was made.

ISSN:0022-233X    

DOI:10.1080/10601327508056931

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The frequently used equation, -d[M]/dt = kp[M][Pn*], which is applicable to homopolymerization reactions, has been modified to accommodate a copolymerization system involving the comonomers propylene oxide (PO) and tetrahydrofuran (THF). The disappearance of PO (M1) and THF (M2) has been related to ki, kt, KPO, KTHF, r1and r2, and a solution to the ensuing six parameter equation is suggested. This involves calculating r1and r2with the aid of the Mayo-Lewis equation, [dM1/dM2] = [M1/M2][M1r1+ M2]/[M2r2+ M1], in the form [dM1/dM2] = K[M1/M2]aand using the O'Driscoll equations to evaluate r1and r2. The remaining four unknown parameters in the equation are then evaluated, to a first approximation, by optimization techniques such as the Gauss, Gradient, and Monte Carlo methods which in turn are modified by the Monte Carlo simulation method with the aid of an IBM 370/158 computer. A flow diagram describing the steps involved in the computation of rate constants is also included.

ISSN:0022-233X    

DOI:10.1080/10601327508056932

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A study of the monomer-isomerization polymerizations of 2-heptene and 3-heptene has been investigated with (C2H3)3Al-TiCl3catalyst at 80°C. It was found that 2-heptene and 3-heptene underwent monomer-isomerization polymerization to give a high molecular weight polymer consisting of 1-heptene units. In these polymerizations the isomerization of both olefinic monomers was observed. The addition of the isomerization catalyst nickel acetyl-acetonate [Ni(acac)2] accelerated these polymerizations. The rate of polymerization of heptene isomers decreased in the following order; 1-heptene ≧ 2-heptene > 3-heptene. The rate of polymerization and the isomer distribution of unreacted olefinic monomer after polymerization occurred via a stepwise double bond migration mechanism. It was also found that the monomer-isomerization copolymerization occurred between trans-2-butene and 2-heptene to give a copolymer cosisting of 1-butene and 1-heptene units. From the results of this copolymerization, the apparent monomer reactivity ratios were obtained as r1= 1.45 ± 0.05 and r2= 0.50 ± 0.10, whereM1is trans-2-butene and M2is 2-heptene.

ISSN:0022-233X    

DOI:10.1080/10601327508056933

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Polyethylenimine-containing cotton fabrics were prepared by reaction of 1-epoxyethyl-3, 4-epoxycyclohexane with cotton fabric impregnated with polyethylenimine of a moderately high molecular weight. Fabrics with a high unremovable polyethylenimine content and with a different degree of cross-linking were obtained. Adsorption of several heavy metal salts such as mercuric chloride and cupric sulfate by the fabrics was investigated. Adsorption was controlled by polyethylenimine content of the fabric, extent of cross-linking, and the pH of the solution.

ISSN:0022-233X    

DOI:10.1080/10601327508056934

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor