摘要:

AbstractThe results of the investigation of polymerization and copolymerization processes of hydrocarbon monomers initiated by compounds of alkaline‐earth metals are summarized. Experimental data on the synthesis of initiators, stereospecifity, kinetics and mechanism of the processes are considered. The pecularities of the process studied are discussed and compared with those of the polymerization initiated by alkali metals, the importance of bimetallic species in polymerization processes being emphasize

ISSN:0323-7648    

DOI:10.1002/actp.1984.010350101

出版商:Akademie Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractThe efficiency of the initiation reaction of the polymerization of isoprene by metallic lithium metal in hydrocarbon media can be increased essentially by activating the metal by increasing its specific surface and by its plastic deformation during the synthesis. The process opens up the possibility to prepare α,ω‐dilithium oligomers without using electron donor additi

ISSN:0323-7648    

DOI:10.1002/actp.1984.010350102

出版商:Akademie Verlag GmbH    

年代:1984

数据来源: WILEY

ISSN:0323-7648    

DOI:10.1002/actp.1984.010350103

出版商:Akademie Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractStructure and reactivities in the cationic polymerization of the heterocyclic monomers is reviewed. Particularly the equilibria between major kinds of active species, including the kinetics of interconversions between the covalent species and the corresponding macroion‐pairs are discussed. Reason for the higher reactivity of the ionic species than of the covalent ones in the chain growth, observed in the majority of studied systems, is confronted with the recently observed similarity in reactivities, found for oxepane. Further evidence is discussed, supporting the earlier formulated opinion that ion‐pairs and ions propagate with similar rate constants. These features of the cationic ring‐opening polymerizations were compared with the cationic vinyl polymerization. In the former process the covalent and ionic active species have separately been observed by NMR and the covalent propagation clearly demonstrated, whereas there is only a secondary and weak support for the covalent growth of vinyl mon

ISSN:0323-7648    

DOI:10.1002/actp.1984.010350104

出版商:Akademie Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractPivaloylation of 2‐hydroxyethyl methacrylate was used to prepare 2‐pivaloyloxyethyl methacrylate which polymerizes by means of radical, anionic and complex‐coordination initiation systems to polymers with various contents of iso‐, syndio‐ and heterotactic triads. From the polymers thus obtained, pivalic groups may be split off with formation of poly(2‐hydroxyethyl methacrylate) having the same tacticity as its polymeric precursor. The products may be hydrolyzed under rather drastic conditions to polymethacrylic acid. The paper reports preparation and the hydrolytic behaviour of polymers in the first and s

ISSN:0323-7648    

DOI:10.1002/actp.1984.010350105

出版商:Akademie Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractDurch Kronenether wird die Ladungstrennung von Alkalialkoholaten in organischen Medien verstärkt. Ihr Einfluß auf den Polymerisationsablauf und auftretende Konkurrenzreaktionen wurde untersucht. Die ausgeprägtere Ladungstrennung bewirkt eine wesentliche Erhöhung der Polymerisationsgeschwindigkeit. Die Geschwindigkeit der Übertragungsreaktion wird dagegen nur geringfügig beeinflußt, wodurch im Vergleich zum Kettenwachstum die Übertragungsreaktion erheblich zurückgedr

ISSN:0323-7648    

DOI:10.1002/actp.1984.010350106

出版商:Akademie Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractThe inhibiting action of carbon monoxide to ethylene polymerization with the catalytic systems Cp2TiCl2/Al(CH3)2Cl and VCl4/Al(C2H5)2Cl has been studied. Both the polymerization rate and molecular weight of the polymers obtained were found to decrease with increasing concentration of carbon monoxide. The value of the relationship between the decay constant of the active sites and the propagation rate constant was determined.

ISSN:0323-7648    

DOI:10.1002/actp.1984.010350107

出版商:Akademie Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractThe kinetics of ethylene polymerization on the catalytic systems Ti(OC4H9)4/Al(C2H5)2Cl in the presence of fine‐grained silicon and aluminium oxides has been studied. The influence of inorganic filler nature and polymerization conditions on the kinetics and molecular weight distribution of polyethylene, formed on the filler surface, is discusse

ISSN:0323-7648    

DOI:10.1002/actp.1984.010350108

出版商:Akademie Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractA new type of metal complex catalysts immobilized on polymer supports has been synthesized. The polymer supports are carbochain polymers (PE, PP, PS, PVC etc.) the surface of which is modified by graft polymerization with functional groups. Transition metal compounds are chemically fixed on the surface of such polymers. The kinetics of poly‐ and copolymerization of ethylene by mobile and immobilized catalytic systems are compared. The mechanism of active center formations in the immobilized systems is suggeste

ISSN:0323-7648    

DOI:10.1002/actp.1984.010350109

出版商:Akademie Verlag GmbH    

年代:1984

数据来源: WILEY

摘要:

AbstractKinetische Kurven der Sauerstoffabsorption und der Änderung der Anzahl der Makromoleküle von Polystyren in der Schmelze im Temperaturbereich 180 bis 210°C wurden gemessen. Die Ergebnisse werden im Rahmen des Modells einer entartet‐verzweigten Kettenreaktion diskutiert. Die Natur der für die Molmasseänderung des Polystyrens verantwortlichen Radikale wurde aufgeklärt. Der Mechanismus der Makromolekülspaltung besteht aus zwei konkurrierenden Reaktionen des Isomerisationszerfalls der Alkoxyl‐ und Peroxidradikale. Die Aktivierungsenergie der Reaktion des Isomerisationszerfalls des Peroxidradikals wurd

ISSN:0323-7648    

DOI:10.1002/actp.1984.010350110

出版商:Akademie Verlag GmbH    

年代:1984

数据来源: WILEY