ISSN:0449-2951    

DOI:10.1002/pol.1964.100020801

出版商:John Wiley&Sons, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractThe polymerization of vinyl alkyl ethers at room temperature or above, to give crystallizable polymers is of considerable interest for both theoretical and practical considerations. The polymerization of these monomers has been studied with metal sulfate–sulfuric acid complex catalysts at 0°C. or above to give high molecular weight, isotactic polymers. Ferric hydrosulfate hydrate and aluminum hexahydrosulfate heptahydrate (AHS) were used as catalysts. The nature of the solvent employed during polymerization with these heterogeneous catalysts was found to be quite important from the point of view of polymerization rate and stereoregularity of the polymer. A vinyl ether having a linear alkyl group polymerizes considerably faster than a monomer having a branched alkyl group. The apparent first‐order rate constant values for the AHS‐catalyzed polymerization of vinyl alkyl ethers havingn‐alkyl groups indicate the following sequence: ethyl>n‐butyl>n‐hexyl =n‐octyl. In the temperature range of 30–58°C. the overall activation energy for the polymerization of vinyln‐butyl ether in heptane with AHS catalyst was found to be 9.7 kcal./mole. Vinyln‐butyl ether was copolymerized withβ‐vinyloxyethyl methacrylate (M2) using AHS catalyst. The average values ofr1= 0.82 an

ISSN:0449-2951    

DOI:10.1002/pol.1964.100020802

出版商:John Wiley&Sons, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractThe study of polymerization of α,ω‐polymethylene diisocyanates, tetramethylene, trimethylene, ethylene, and methylene diisocyanate, was carried out by the use of basic catalysts and polar solvents. Soluble polymers were obtained. Structures of the polymers were determined on the basis of solubility, infrared absorption, x‐ray diffraction, and chemical reactions, especially aminolysis of the polymers. It was shown that these polymers contained heterocyclic recurring units (imidazolidone and imidazoline) in each polymer chain. Finally, a possible mechanism of this kind of cyclopolymerization is desc

ISSN:0449-2951    

DOI:10.1002/pol.1964.100020803

出版商:John Wiley&Sons, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractThe curing reaction of an epoxy resin and acid anhydride with an amine and/or acid, alcohol, and phenol was studied kinetically by using commercial epoxy resins and acid anhydrides. No etherification reaction occurred at 70–140°C., even in the case of epoxide/acid anhydride/HA (acid, alcohol, or phenol) and of epoxide/acid anhydride tertiary amine/HA, and the initial reaction rate was proportional to the concentrations of epoxide, acid anhydride, and catalysts such as tertiary amine, acid, alcohol, and phenol. The apparent activation energy of the reaction system of Epikote 828/methyl‐bicyclo(2,2,1)heptene‐2,3‐dicarboxylic anhydride/triethanol amine/HA was obtained as about 14.7 kcal./mole, and the low frequency factors and large negative entropies of activation for the reaction might confirm that the curing reaction of epoxy resins and anhydrides belongs to the type of nucleophilic bimolecular displacement reaction. The effects of the substituents, R, of acid, alcohol, and phenol as cocatalyst on the curing reaction of epoxy resin/acid anhydride/tertiary amine/HA were studied. The reaction constants,p, obtained positively for HA's, indicate that electron‐withdrawing substituents of HA increase the rate of curing reaction of system of epoxide/acid anhydride/amine/HA. Differences in the catalytic and cocatalytic effects among benzoic acid, benzyl alcohol, and phenol in these reaction systems might be considered to depend on the donating power of hydrogen bond which is the important role rather than a general electrostatic interaction effect as solvent effects in nucleophilic substitution reactions. These results supported the proposed mechanisms

ISSN:0449-2951    

DOI:10.1002/pol.1964.100020804

出版商:John Wiley&Sons, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractConversion curves of molten trioxane polymerization at temperatures between 70 and 90°C. have been measured. Their analysis has established that the rate‐controlling step of the reactionis the addition of a trioxane molecule to the active center. Values of the rate constantsk1andk3k4/k2as well as the rate constants of initiator deactivationkshave been determined. Initiator deactivation causes premature leveling off of the conversion curves, especially at lower temperatures of polymerization (70–80°C.). The activation energies of the rate constants have been deter

ISSN:0449-2951    

DOI:10.1002/pol.1964.100020805

出版商:John Wiley&Sons, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractKinetic analysis of the induction periods of trioxane polymerization shows that although the interaction of the initiator with a trioxane molecule is slow, the reaction of the initiator with free formaldehyde (followed by the splitting of trioxane) is quick and yields active centers. Kinetic relations have been developed for the amount of free formaldehyde in the first stages of the reaction between the initiator and trioxane, for the rate of formation of active centers and for the time dependence of the conversion of trioxane during the induction period. Kinetic formulas are compared with experimental data.

ISSN:0449-2951    

DOI:10.1002/pol.1964.100020806

出版商:John Wiley&Sons, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractA method of estimating molecular weight distributions of polymer fractions which was proposed previously is investigated. The distribution curves calculated by the proposed method are compared to the experimental curves. Several numerical experiments are also carried out to discuss a nonsystematic change of the fractionation parameters.

ISSN:0449-2951    

DOI:10.1002/pol.1964.100020807

出版商:John Wiley&Sons, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of polyoxymethylene and irradiated polyoxymethylene in vacuum was carried out and the kinetic aspects of thermal decomposition discussed. Although decomposition of low viscosity polyoxymethylene followed a pattern in which log (polymer residue) was roughly linear with decomposition time, the high‐viscosity polyoxymethylene which was obtained by the post‐polymerization of irradiated solid formaldehyde showed the two components different in stability. However the concentrations of the components depended on the decomposition temperature. After the thermal decomposition, the sample could not be further stabilized by acetylation, while this initial polymer could be highly stabilized by acetylation. The irradiated polymer also could not be thermally stabilized by acetylation, though the first component of the irradiated polyoxymethylene disappeared after acetylation. The components of the polymer irradiated at 100°C., ∼4 Mr (ηsp/c= 0.23) showed three components the concentrations of which are independent of decomposition temperature. In irradiation at room temperature, or in the case of irradiation by the electron beams from a Van de Graaf generator at a high dose rate, the evacuation at 100°C. of the irradiated sample after irradiation disclosed the clear dependence of formation of stable polymer on dose, and the formation of three components which are independent of the decomposition tem

ISSN:0449-2951    

DOI:10.1002/pol.1964.100020808

出版商:John Wiley&Sons, Inc.    

年代:1964

数据来源: WILEY

摘要:

Abstract4‐Methylene‐1,3‐dioxolane and its derivatives were polymerized by cationic catalysts. Infrared and ultraviolet studies showed that the polymers of 2,2‐dimethyl‐ or 2‐methyl‐1,3‐dioxolane possess appreciable carbonyl content. This indicates that the polymerization takes place in such a manner that the carbon–carbon double bond opening is coupled with a concurrent acetal ring rearrangement in the propagation step to give “ketoether” sequences. 4‐Methylene‐1,3‐dioxolane, on the other hand, was found to polymerize mostly at the carbon–carbon double bond. Copolymerization of these monomers with acrylonitrile under ultraviolet

ISSN:0449-2951    

DOI:10.1002/pol.1964.100020809

出版商:John Wiley&Sons, Inc.    

年代:1964

数据来源: WILEY

摘要:

AbstractThe divinylacetal of (R)(+)‐3,7‐dimethyloctanal was polymerized by radical and cationic initiators. Radical initiation gave only viscous liquid polymers, while cationic systems gave solid products. Optical rotatory dispersions of these polymers fit simple Drude plots. The polymer prepared by boron trifluoride etherate exhibits negative optical rotations, while both the polymer obtained by azobisisobutyronitrile and the model compound show positive rotations. From these observations, it is suggested that the polymers might differ from each other in stereoregular

ISSN:0449-2951    

DOI:10.1002/pol.1964.100020810

出版商:John Wiley&Sons, Inc.    

年代:1964

数据来源: WILEY