摘要:

AbstractIn order to clarify the mechanism of the catalytic reactions of poly(acrylhydroxamic acid)‐copper chelates on the decomposition reaction of hydrogen peroxide, the stability constants of these chelates were measured by using a modified BJERRUM'S method, and each fraction of chemical species was estimated on the basis of chelate chemical theory. The chelate formation proceeds through the following two steps:where HL means the ligand group, b1and b2mean the stability constants of CuL+ and CuL2, respectively. The value of b1decreased with the increase of the ratio of the total concentration of cupric ion to the total concentration of the ligand, TCu/THLand with the increase of the molecular weight of the ligand polymer. The variation of the value of b2was more significant than the variation of the value of b1. Therefore, it was confirmed that the increase of TCu/THLand the increase of the molecular weight of the ligand polymer resulted in the increase of the fraction of CuL+species in the chelate‐poly

ISSN:0025-116X    

DOI:10.1002/macp.1968.021150101

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractDecomposition reaction of hydrogen peroxide was effected under various conditions by using poly(acrylhydroxamic acid)‐copper chelates as catalysts. The catalytic effect of these chelates is discussed on the basis of kinetic data concerning, with chelate formation from the polymeric ligands (L). The initial rate of the decomposition reaction which depended upon the initial concentration of hydrogen peroxide, increased with the ratio of total concentration of cupric ion to total concentration of the ligand group (TCu/THL). The relation between initial rate and the initial concentration of hydrogen peroxide varied in accordance with the rate expression of MICHAELIS‐MENTEN type. These experimental results are discussed on the basis of values of chelate formation constants obtained in the preceding paper. Thus, the chemical species which contribute to the catalytic activity were assumed to be CuL+,e.i., the chemical species derived from a cupric ion and one hydroxamic group. So, an addition of this ligand in excess with respect to formation of CuL+caused competitive inhibition for the decomposition reaction of hydrogen perox

ISSN:0025-116X    

DOI:10.1002/macp.1968.021150102

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractDie Dehydrochlorierung des Poly(vinylchlorid‐co‐α‐chloracroleindimthylacetals) mit Natriumamid in Ammoniak oder Tetrahydrofuran führt schon bei einem Chlorgehalt unterhalb 36,5% zu unlöslichen Produkten. Mit Kalium‐tert‐butylat waren die Dehydrochlorierungsprodukte dagegen noch his zu einem Gehalt vonca.10% Chlor löslich. Die Delhydroclorierungsgeschwindigkeit ist beim Kalium‐tert‐butylat praktisch unabhüngig von der Copolymerzusammensetzung. Bei hohen Basenkonzentrationen und kleinen Dehydrochlorierungsgraden hängt die Geschwindigkeit nur von der Chlorkonzentration ab, bei hohen Dehydrochlorierungsgraden dagegen nur noch von der Basenkonzentration. Für diese Grenzfälle wurden die ungewöhnlichen Exponenten von 3,3 Für die Chlorkonzentration bzw. 4,3 Für die Basenkonzentration gefunden. Das Heptaen weist unterhalb eines Chlorgehaltes von etwa 34% immer das höchste Absorptionsmaximum auf, wenn von einem Copolymeren mit 74 Mol‐% Vinylchlorid ausgegangen wird. Die Reaktionstemperatur hat keinen Einfluß auf die Sequenzverteilung der konjugierten Doppelbindungen. Dien‐ und Trien‐Sequenzen sind bei allen Reaktio

ISSN:0025-116X    

DOI:10.1002/macp.1968.021150103

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractCopolymerizations of ε‐caprolactam, α‐pyrrolidone or α‐piperidone with ε‐caprolactone or δ‐valerolactone have been carried out in the presence of alkali metal. It has been shown that in copolymerizations of ε‐caprolactam or α‐pyrrolidone with ε‐caprolactone and α‐pyrrolidone with δ‐valerolactone conversions of above 70 % and reduced viscosities of above 0.5 inm‐cresol at 35°C for all compositions were obtained. In the case of copolymerization of ε‐caprolactam with δ‐valerolactone at 180°C a conversion of 25 % and a reduced viscosity of 0.5 were obtained, but the polymer was polycaproamide, while at 90°C the conversion was 50 % but the polymer was polyvalerolactone. In copolymerizations of α‐piperidone with ε‐caprolactone or δ‐valerolactone the copolymer contained only polyester.A mechanism is proposed for the copolymerization of ω‐lactams with ω‐lactones with alkali metal, which involves chain propagation by the stepwise addition of the lactam ring at an end of the chain molecule and by the stepwise addition of the lactone ring at the other end of the chain molecule, resulting to a certain extent in the formation of polyester and polyamide segments.This mechanism is supported by experimental results obtained through the reaction in the presence of alkali metal salts of ω‐lactam, data on infrared analyses and elementary analyses, and by experimental results obtained throu

ISSN:0025-116X    

DOI:10.1002/macp.1968.021150104

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractEs wurden niedermolekulare Modelle von Chloropreneinheiten dargestellt, die in 1.2‐oder 1.4‐Stellung in der Polymerkette angeordnet sind. Durch homogene Polymerisation von Vinylacetat und Chloropren in Gegenwart dieser Modellverbindungen wurden ihre relativen Übertragungskonstanten in beiden Monomeren bestimmt. Aus den relativen Übertragungskonstanten wurden die individuellen Geschwindigkeitskonstanten der Reaktionen der 1.2‐ und 1.4‐Polychloroprenstrukturen mit den Polyvinylacetat‐ und Polychloropren‐Radikalen berechnet. Auf Grund der gewonnenen Daten wird die relative Reaktivität der Initiator‐ und Polymer‐Radikale gegenüber den chemischen Mikrostrukturen der Polychlor

ISSN:0025-116X    

DOI:10.1002/macp.1968.021150105

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractWith the aim of preparing copolymers of trioxane with acenaphthylene, the polymerization of a mixture of both monomers was carried out in the presence of boron trifluoridediethyl etherate in benzene and tetrachloromethane and in melt. In most monomer ratios, irrespective of the degree of conversion, products were obtained, which were composed of two fractions: one fusible and soluble in benzene and tetrachloromethane, containing almost pure polyacenaphthylene, and another infusible and insoluble in organic solvents with a high polyformaldehyde content. On polymerization of the monomer mixture under the action of γ‐rays only insoluble and infusible products were formed. On the basis of the experimental results and the literature data an attempt is made to explain the formation of insoluble products and an opinion is expressed, that no copolymerization of the monomers is likely to take place under the experimental conditions employ

ISSN:0025-116X    

DOI:10.1002/macp.1968.021150106

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractButyllithium (BuLi) initiates α‐methylstyrene polymerization in bulk at room temperature. Both initiation and propagation reactions are very slow and propagation/depropagation occurs along with other side reactions,e.g., transfer. At slightly elevated temperatures (40–50°C) irreversible termination takes place. Molecular weights change inversely but not linearly with changes in [BuLi] and distributions are broad (M̄w/M̄n= 1.55 to 2.2) as would be expected from equilibria considerations. These results are generally different than those reported with sodium initiated re

ISSN:0025-116X    

DOI:10.1002/macp.1968.021150107

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractBinary copolymerizations of ethylene, propylene and butene‐1 were studied. The copolymers show a tendency to an alternating sequence distribution if prepared by syndiospecific catalysts, whereas they show a random distribution when prepared by non‐stereospecific or by isospecific catalysts.These facts indicate that syndiotacticity is due to steric interactions between monomer and last unit of the growing chain end and that isotacticity is due to steric interactions between monomer and counter‐ion. The propylene‐butene‐1 copolymerization shows that the side‐chain rotations of the last added unit are hindered in the presence of syndiospecifi

ISSN:0025-116X    

DOI:10.1002/macp.1968.021150108

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractRate constants of the thermal degradation of polymethylmethacrylate fractions have been measured over a range of temperatures, and the ARRHENIUS equations have been derived. There are two degradation reactions for this polymer; one “fast” reaction, which is chain‐end initiated, due to double‐bonded chain‐end polymer molecules and one “slow” reaction, which is initiated at random. The energy of activation for the fast reaction is much smaller than that of the slow reaction. Both show two levels of energies of activation proceeding from long to short chains. These energies of activation increase with decreasing chain length of the polymer as expected from theory. Whereas the differences in energies for the fast reaction are in agreement with a mechanism consisting of chain‐end initiation, depropagation, and second‐order termination, a reasonable value for the overall energy for the slow reaction is only obtained for a first‐order termination process. Such a reaction is not unlikely, as the polymer film contains appreciable amounts of monomer at this stage of degradation. The energies of activation for the slow reaction increase with percentage conversion as long as some double‐bonded chain ends are still in the system. It has to be concluded that the degradation of isotactic and syndiotactic polymethylmethacrylate, which degrade by random initiation, also have a first‐order termination reaction. On the basis of the results reported here, the confusion in the literature concerning energies of activation for the thermal degradation of polymethylmethacrylate can be understood. These energies do not only depend on chain length but also on the mechanism of the degradation process, range of conversion, and percentage of double‐bonded

ISSN:0025-116X    

DOI:10.1002/macp.1968.021150109

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY

摘要:

AbstractDiethylzinc/water system was studied using infrared spectroscopy, X‐ray diffraction, and vapor phase chromatography. The main reactions of diethylzinc with water are considered to be as follows:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} {\rm ZnEt}_{\rm 2} \, + \,{\rm H}_{\rm 2} {\rm O}\, \to \,{\rm EtZnOH}\, + \,{\rm EtH} \\ {\rm n}\,{\rm EtZnOH}\, \to \,{\rm (EtZnOH)}_{\rm n} \to \,{\rm Et(ZnO)}_{\rm n} {\rm H} + ({\rm n} - 1){\rm EtH} \\ {\rm Et(ZnO)}_{\rm n} {\rm H}\, + \,{\rm ZnEt}_2 \to \,{\rm Et}({\rm ZnO})_{\rm n} {\rm ZnEt} + {\rm EtH} \\ {\rm Et(ZnO)}_{\rm n} {\rm H} + {\rm H}_{\rm 2} {\rm O} \to \,{\rm HO(ZnO)}_{\rm n} {\rm H} + {\rm EtH} \\ \end{array} $$\end{document}Relative LEWIS acidity for ether is found to be in the order:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm HO(ZnO)}_{\rm n} {\rm H} < {\rm ZnEt}_2 < {\rm Et(ZnO)}_{\rm n} {\rm ZnEt} < {\rm AlEt}_3 $$\end{document}Initiators for the polymerization of propylene oxide by diethylzinc/water system are found to be Et(ZnO)nZnEt, Et(ZnO)nH, or HO(ZnO)nH, which have disordered wurtzite structures concerning zinc‐oxygen bond. On the hydrolysis of the polymerization system, 2‐methyl‐l‐butanol, 2‐pentanol, and propylene glycol are found as initial products. The main reaction of the polymerization of propylene oxide catalyzed by diethylzinc/water system was discussed in terms of the coordinate ioni

ISSN:0025-116X    

DOI:10.1002/macp.1968.021150110

出版商:Hüthig&Wepf Verlag    

年代:1968

数据来源: WILEY