摘要:

Equations are derived for assessing the effects due to penultimate units in terpolymerization on composition equations. Equations of varying scope are offered for the penultimate-unit effects indicated. In all the examples treated, one monomer is assumed to be incapable of self-propagation.

ISSN:0022-233X    

DOI:10.1080/10601326808051447

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Kinetics studies, using the gas-chromatographic method, of the two copolymerizations acrylonitrile-methyl methacrylate and styrene-acrylonitrile, show that remote units effects do operate on the reactivity of each radical species. The corresponding reactivity ratios are:

ISSN:0022-233X    

DOI:10.1080/10601326808051448

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A study of the polymerization of styrene, methyl methacrylate, acrylonitrile, vinyl acetate, and vinyl chloride initiated by various metal acetylacetonates [Me(acac)x] has been made. It was found that Mn(acac)3was the most effective initiator, and Co(acac)3, Mn(acac)2, Cu(acac)2, and Cr(acac)3showed moderate activity for the polymerization of methyl methacrylate at 60°C. However, the other, Me(acac)x, had no effect or served as inhibitors. The addition of some additives such as halogen compounds did not accelerate polymerization of methyl methacrylate by Mn(acac)3, From the results of polymerization and copolymerization of methyl methacrylate by Mn(acac)3, it was concluded that the polymerization proceeded via an ordinary radical mechanism and the activation energy for initiation was 25.2 kcal/mole. The initiation mechanism of vinyl polymerization by Me(acac)xwas studied on the basis of the complex formation with the monomer.

ISSN:0022-233X    

DOI:10.1080/10601326808051449

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Radiation-induced solid-state polymerization of acrylonitrile at low temperature is reported. It is pointed out that the rate of polymerization may be extremely rapid in the initial stage of polymerization in comparison with those induced with other radiation sources, that the effect of fast neutrons is significant in the polymerization, and that formation of both trans-vinylene and C˭C bonds conjugated with C≡N groups can be observed only in polymerization initiated with reactor radiation.

ISSN:0022-233X    

DOI:10.1080/10601326808051450

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Solid-state polymerization of acrylonitrile induced by reactor radiation, including recoil particles from a nuclear reaction of10B (n, α)7Li, was carried out at low temperature. It was observed from the experiments that the effect of the recoil particles on polymerization is significant. The effect is characterized by cross-linking of polymers produced, and formation of trans-vinylene and C≡C bonds conjugated with a bond C˭N group in the polymerization during irradiation.

ISSN:0022-233X    

DOI:10.1080/10601326808051451

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Relative reactivities of α,β-unsaturated carbonyl compounds toward n-butylmagnesium bromide are determined by competitive reactions with diethyl ketone. α-Methyl group significantly suppresses the reactivity of the acrylic ester in ether, but enhances the reactivity of the unsaturated nitrile under the same condition. A striking decrease in reactivity is caused by the β-methyl group in crotononitrile. whereas methyl crotonate is only slightly less reactive than methyl methacrylate. α-Methyl and β-methyl sub-stituents in unsaturated ketones behave in a similar way to those in the unsaturated esters. Polar solvents, in general, elevate reactivity of β-methyl compounds relative to α-methyl ones. The homolytic (or heterolytic) character of the Grignard reactions is discussed quantitatively in terms of the relative reactivities of the three homologous (unsubstituted, α-substituted, and β-substituted) unsaturated compounds.

ISSN:0022-233X    

DOI:10.1080/10601326808051452

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Poly condensation of aluminum butoxide with α, ω -dihydroxydi-methylsiloxanes having varied polymerization coefficients has been studied. Some kinetic dependencies in the generation of cyclonetwork poly(aluminum dim ethylsiloxanes) have been investigated and the rate constants of cross-linking reaction, depending on the chain length of initial α, ω-dihydroxypolydimethylsiloxanes, have been calculated.

ISSN:0022-233X    

DOI:10.1080/10601326808051453

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The synthesis, thermal stability, and the nature of the pyrolytic decomposition of polymeric azines,in which R is H and CH3, are reported. These polymers were synthesized by the continuous azeotropic method to yield yellow, insoluble, infusible brick-dust polymers, and by exchange reactions in melts to obtain dark-colored, tractable, fusible polymeric azines which, on heating, became insoluble and infusible and were converted to polystilbene-type polymers. The azine polymers were not very thermally stable; they decomposed thermally at approximately 300°C to yield substantial quantities of nitrogen with the concomitant formation of stilbene segmers in the polymer chains. The derived polymers were thermally stable and their physical characteristics paralleled those of the poly-Schiff bases. Calorimetric and kinetic data on the decomposition reaction of the polyazines are discussed.

ISSN:0022-233X    

DOI:10.1080/10601326808051454

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The potentiometric behavior of DEAE-dextran base in aqueous solutions of varying ionic strengths was investigated. Owing to the presence of three different basic groups in the compound, the analysis of the titration curves obtained is quite complicated. Therefore, only the titration range of one of the basic groups present was analyzed in detail and the values of the electrostatic potential at the surface of the polyion were obtained. These values were compared with those calculated from a cylindrical model for the polyion assuming a uniform distribution of charges on the surface. Agreement between the two sets of values is rather poor, which indicates that the model is inappropriate.

ISSN:0022-233X    

DOI:10.1080/10601326808051455

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Molecular weight distributions in poly(vinyl chloride) resins have been determined from simple viscosity measurements. Ratio of 11% solution viscosity to intrinsic viscosity yielded a figure which has been correlated with molecular weight distributions obtained (1) from the ratio of weight-average to number-average molecular weights and (2) from gel permeation chromatography. Ratio of viscosities is thus a useful short-cut technique for obtaining approximate molecular weight distributions in poly(vinyl chloride) resins which have 0. 77 < [η] < 1.15 and 1. 6 < ROM < 2. 8.

ISSN:0022-233X    

DOI:10.1080/10601326808051456

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor