摘要:

AbstractDie gleichzeitige Wirkung verschiedener aktiver Zentren in ionischen Systemen wird sowohl unter dem Aspekt ihrer Besonderheiten als auch hinsichtlich ihres relativen Anteils an experimentellen Gesamteffekten betrachtet. Bildungsweise und konkrete Typen von koexistierenden aktiven Zentren in anionischen, kationischen und durch Übergangsmetallderivate initiierten Polymerisationsprozessen werden diskutiert. An Beispielen der Aggregierung, Dissoziation, Isomerisation, intermolekularen und intramolekularen Komplexbildung werden die Mehrzentreneffekte besprochen

ISSN:0323-7648    

DOI:10.1002/actp.1983.010341102

出版商:Akademie Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractActivation processes of homogeneous catalytic systems of ethylene polymerization on the basis of Cp2TiEtCl are analyzed. The kinetic and27Al‐NMR data lead to the conclusion that the active center of polymerization has the structure (Cp2TiEtCl · Y)H+Y′B−, which involves Lewis acids Y and Y′ and the proton‐donor m

ISSN:0323-7648    

DOI:10.1002/actp.1983.010341103

出版商:Akademie Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractThe initiation of styrene polymerization with n‐butyllithium in toluene was investigated spectrophotometrically. The rate of the first step of initiation is first order in both monomer and catalyst, and the activation energy is 26.3 kJ · mol−1. The kinetic analysis revealed a number of kinetic transitions attributed to the formation of secondary aggregates from reacted and unreacted n‐C4H9Li. The molecular weight distribution narrows with increasing reaction temperature, indicating the activation energy of the last step of initiation to be higher than that of propa

ISSN:0323-7648    

DOI:10.1002/actp.1983.010341104

出版商:Akademie Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractSome results obtained in the investigation of cationic polymerization of unsaturated C5hydrocarbons with AlCl3‐based catalysts are presented. The effect of catalytic complexes and polymerization process on the efficiency of AlCl3is discussed. Based on the experimental data of the polymerization process and conductometric determinations the investigated reaction is discussed within the framework of current concepts on the mechanism of cationic polymerizations catalyzed by aluminium halide

ISSN:0323-7648    

DOI:10.1002/actp.1983.010341105

出版商:Akademie Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractThe report presents kinetic studies on the ring opening polymerization of cyclopentene carried out with the following catalytic systems:andThe relation between the nature of the aluminium‐organic compound, the structure of the polymers and some of their properties was also investigated. The polymerization follows in both cases the same kinetic pattern which include an instantaneous initiation and a bimolecular termination reaction. The resulting polymers present different microstructures and properties due to the different concentrations of active centers, which occur in the presence of the two investigated catalytic systems and to side reactions during the polymerization proces

ISSN:0323-7648    

DOI:10.1002/actp.1983.010341106

出版商:Akademie Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractTwo groups of active centers in the system δ‐TiCl3/AlEt3have been found: the first one was formed by the interaction of TiCl3with AlEt3, and the other one was formed as the result of the reaction of TiCl3with AlEt2Cl which appeared after the alkylation reaction of TiCl3. There exists a distribution of active centers with respect of their activity and stereospecificity in both groups. By the influence of the donor an increase of the iso‐addition rate constant and the stereoregular ability of isotactic centers takes p

ISSN:0323-7648    

DOI:10.1002/actp.1983.010341107

出版商:Akademie Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractA survey of investigations on the copolymerization of episulphides with epoxides, isothiocyanates and some polar vinyl monomers under the influence of catalyst systems of anionic, cationic and coordinate‐ionic types is presente

ISSN:0323-7648    

DOI:10.1002/actp.1983.010341108

出版商:Akademie Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractAn exceptional acceleration of the bulk heterogeneous polymerization of 2‐pyrrolidone, initiated with the potassium salt of 2‐pyrrolidone, was attained by addition of 1‐(1‐pyrrolin‐2‐yl)‐2‐pyrrolidone (PDPD). The kinetic analysis shows that the mechanism of this polymerization is complex, but that the polymerization resembles a nonactivated polymerization by several features. The function of PDPD cannot be decided for the present, but it seems to be rather a regulator than an activator of

ISSN:0323-7648    

DOI:10.1002/actp.1983.010341109

出版商:Akademie Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractThe problems of initiation in the cationic polymerization of vinylic monomers are discussed. The absorption bands were identified in a model system with participation of 1,1‐diphenyl ethylene and its dimers and tetracyan ethylene was disclosed. The absorption bands in the region of 400 nm observed with the reaction system with participation of 1‐methyl‐1,3,3‐triphenyl indan and tetracyan ethylene and at 388 nm and 524 nm with the system of 1,1,3,3‐tetraphenyl butene‐1 and tetracyan ethylene were identified as absorption bands of charge transfer complexes. Conclusions are drawn to the mechanism of dimerization of 1,1‐diphenyl ethylene in the presence

ISSN:0323-7648    

DOI:10.1002/actp.1983.010341110

出版商:Akademie Verlag GmbH    

年代:1983

数据来源: WILEY

摘要:

AbstractThe kinetics of cyclotrimerization of mono‐ and diarylcyanates in the presence of ZnCl2in substance as well as in nitrobenzene and ditolylmethane has been investigated. The reaction was found to be accelerated. The order of reaction of the monomer and catalyst were determined. The acceleration of the cyclotrimerization of arylcyanates by ZnCl2is caused by rearrangement of the coordination sphere of Z

ISSN:0323-7648    

DOI:10.1002/actp.1983.010341111

出版商:Akademie Verlag GmbH    

年代:1983

数据来源: WILEY