摘要:

AbstractOn the basis of the factorial method of experiment design the radical copolymerizations of acrylonitrile with zinc or copper acrylate in dimethylformamide solution have been studied. The constants of the kinetic equations are clearly dependent on the kind of metal iron in the acrylate.

ISSN:0323-7648    

DOI:10.1002/actp.1990.010410401

出版商:Akademie Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe determination of the polymerization rate, which is easily made in batch polymerization, may become difficult for continuous polymerization processes, because in the general equationRp= –(1/V) dM/dtthe parametertreperesents the residence timetrand this depends not only on the feeding rates, but also on the composition of the reaction mixture, especially when polymerization occurs with a great volume contraction. In this study diagrams are presented which permit the rapid determination ofRpandtrfor continuous emulsion polymerization of vinyl chloride from the functional parameters of the reacto

ISSN:0323-7648    

DOI:10.1002/actp.1990.010410402

出版商:Akademie Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe kinetics of the batch emulsion polymerization of vinyl chloride with redox initiation systems consisting of potassium persulphate, sodiumformaldehyde sulphoxylate and ferrous sulphate as a complex with Na2‐EDTA was studied. In these systems the main influence on the polymerization kinetics is provieded by the concentration of sodiumformaldehyde sulphoxylate and by the ration of the components. Potassium persulphate represents a kind of raw materials for generating the free radicals of initiation, but the amount of the radicals depends on the other components of the redox syste

ISSN:0323-7648    

DOI:10.1002/actp.1990.010410403

出版商:Akademie Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe semicontinuous emulsions copolymerization of vinyl acetate with 2‐ethylhexyl maleate has been studied. The amount of polymer obtained during the continuous addition of commonomers increases at first nonlinearly than linearly with time. During this period the viscosity of the obtained emulsion is not proportional to the polymer content. The conversions are affected by the reaction conditions, e.g. the stirring rate and the amount of the transfer agent n‐butanol and its distribution between the initial reactor charge und the continuously introduced comonom

ISSN:0323-7648    

DOI:10.1002/actp.1990.010410404

出版商:Akademie Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe morphology of ethylene‐vinyl chloride copolymeres containing up to 8 wt% vinyl chloride obtained in various copolymerization conditions is studied. Fundamental morphological units of the copolymers were determined, and one of the most probable mechanisms responsible for their aggregation in the course of the synthesis is considered. This made it possible to demonstrate the possibility of controlling the copolymer bulk density. The supermolecular structure of the copolymers is mainly affected by the solvent used as copolymerization mediu

ISSN:0323-7648    

DOI:10.1002/actp.1990.010410405

出版商:Akademie Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe carboxymethylation of original and activated cellulose in the system cellulose/NaOH/isopropyl alcohol/CH2ClCOOH has been investigated by means of conductometry, viscosimetry and X‐ray diffractometry. It has been found that the carboxymethylation process in this system is a pseudo‐first‐order reaction with two stages having different first‐order rate constants. By application of the activation method the rate of etherification and the utilization ratio of the etherifying agent were increased and the quality of the product was i

ISSN:0323-7648    

DOI:10.1002/actp.1990.010410406

出版商:Akademie Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractGraft copolymerization of ethyl acrylate onto starch in aqueous medium was studied using various concentrations of ceric ions as initiator. It was found that termination of copolymerization occurred mainly by the interaction of ceric ions with the growing graft polymer chain. The value of the chain transfer constant was determined. Further the graft copolymerization of ethyl acrylate onto starch in the presence of small quantities of acrylonitrile was examined. An increase in the amount of acrylonitrile in the monomer mixture did not produce a corresponding increase in the amount of the monomer in the graft copolymer.

ISSN:0323-7648    

DOI:10.1002/actp.1990.010410407

出版商:Akademie Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractThe catalytic degradation of poly(isobutylene) under the action of AlBr3and AlEtCl2in aliphatic solvents was studied at 20 to 60°C, and the kinetic features of the process were established. The investigation of the influence of 2,6‐di‐tertbutylpyridine showed its indifference towards the degradation process, while O2, p‐benzoquinone, and tetracyanoethylene have an inhibiting effect. On the basis of EPR studies the posibility of a radical chain mechanism of the degradation reaction could be

ISSN:0323-7648    

DOI:10.1002/actp.1990.010410408

出版商:Akademie Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractAnhand von 9 Cellulose‐2,5‐acetat‐Proben wurden verschiedene Arbeitsweisen der Partialfraktionierung durch Extraktion mit einem Aceton‐Wasser‐Gemisch (55:45 Masse‐%) und durch Fällung aus Acetonlösung mit der entsprechenden Wassermenge verglichen. Bei Längerer Standzeit vor der Aufarbeitung der Franktionen wurde eine erhebliche Deacetylierung beobachtet. Der unter sonst vergleichbaren Bedingungen in Lösung befindliche Polymerianteil war bei der Fällfraktionierung stets größer als bei der Extraktion. Die Aussagemöglichkeiten der angewandten Methoden für die Charakterisierung von Celluloseacetat

ISSN:0323-7648    

DOI:10.1002/actp.1990.010410409

出版商:Akademie Verlag GmbH    

年代:1990

数据来源: WILEY

摘要:

AbstractFür verschiedenartige ionische (NaCMC, NaCS) und nichtionische (Cellulose‐2,5‐acetat, DA‐Xanthat) Cellulosederivate wurden unter Einbeziehung unterschiedlich beschaffener Versuchsmuster und Verwendung von Lösemittel/Fällungsmittel‐Systemen aufsteigender Lösekraft Löslichkeitskurven ermittelt. Es zeigte sich, daß die Löslichkeitskurven ein hervorragendes Mittel zur Produktcharakterisierung vor allem dann darstellen, wenn der DS des Derivates niedriger order nicht wesentlich höher liegt, als für dessen vollständige Auflösbarkeit erforderlich ist. Zur Stützung der Schlußfolgerungen Bezüglich der das Löseverhalten der Proben bestimmenden Einflußfaktoren wurde eine nähere Charakterisierung von Fraktionen vorgenommen; sie führte zu nachfolgender Rangordnung für die gefundenen Einflußfaktoren: DS, Substituentenverteilung zwischen den Ketten, Substituentenverteilung entlang der Kefte, DP und Kettenlängenverteil

ISSN:0323-7648    

DOI:10.1002/actp.1990.010410410

出版商:Akademie Verlag GmbH    

年代:1990

数据来源: WILEY