摘要:

AbstractDie Untersuchung der Regelung der Trioxanpolymerisation durch verschiedene Kettenüberträger führte zu dem Ergebnis, daß während der Polymerisation als Nebenreaktion eine Hydridwanderung stattfindet. Analytische Untersuchungen erhärteten diesen Befund. Die intramolekulare Hydridwanderung liefert Methylkationen, die ihrerseits die Polymerisation oder eine Transacetalisierung auslösen. Hydridwanderung und Transacetylisierung sind für die kationische Polymerisation von Trioxan und Formaldehyd charakteristisch.Weitere Untersuchungen führten zur Auffindung neuer Regler, wie Borsäureester und alkylsubstituierte Aromaten. Ferner gelang es, Polyoxymethylene mit ungesättigten, Nitril‐ und Peroxy‐Endgruppe

ISSN:0025-116X    

DOI:10.1002/macp.1966.020900101

出版商:Hüthig&Wepf Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractStereoregulating behaviour of organoalkali and organoalkaline earth metal compounds in methyl methacrylate (MMA) polymerization has been studied. Low temperature and polar solvents such as tetrahydrofuran (THF) favour formation of syndiotactic polymer when lithium and magnesium ketyls are used as catalysts. Whereas isotactic polymer is obtained with sodium ketyl even in THF at −70°C.Lithium aluminum hydride (LiAlH4) gave almost complete isotactic polymer in high conversion in diethyl ether or toluene even at low temperature, and lithium aluminum tetraethyl (LiAlEt4), on the other hand, gave very highly syndiotactic polymer under the same conditions. The solvent, besides, showed very important role in stereoregulation, that is, LiAlH4could give syndiotactic polymer in a polar solvent at low temperature.Polymer structure was analyzed by NMR‐ and IR‐spectroscopy.The electrical conductivities of these catalyst systems were measured and there was found a parallelism between those values and stereoregularities of polymers obtained by the respective catalyst s

ISSN:0025-116X    

DOI:10.1002/macp.1966.020900102

出版商:Hüthig&Wepf Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractThe cycloolefins cyclopentene, 3‐methylcyclopentene, and 3‐methylcyclohexene have been polymerized. The polymerization rates were very low. Depending on the particular monomer, ZIEGLER and/or cationic catalysts were effective. Cyclopentene polymerizes both by double bond opening (producing enchained cyclopentane rings) and by ring opening to givecisandtranspolypentenamers. The resulting polymers are partially crystalline and have birefringence melting points between 120 and 150°C. The 3‐methylcyclopentene and 3‐methylcyclohexene monomers polymerize (at least partly) by 1,3‐addition following a 3,2‐hydride shift. The 3‐methylcyclohexene polymers are also partly crystalline and have birefringence melting points between 200 and 250°C. Little ring‐opening polymerization of the methylcycloolefins occurs. Polymerization mechani

ISSN:0025-116X    

DOI:10.1002/macp.1966.020900103

出版商:Hüthig&Wepf Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractSiloxan‐bis(β‐diketone) wurden durch Addition von 4,4‐Diacetylbuten‐1 an α,ω‐Dihydrogensiloxane hergestellt und nach verschiedenen Methoden durch Reaktionen mit Metallverbindungen in Polymere übergeführt, die in der Hauptkette alternierende Metallchelatgruppen, Trimethylen‐ und Dimethylsiloxangruppen enthalten. Am besten bewährte sich die Methode der wasserfreien Umsetzung der Bis(diketone) mit BeCl2ohne

ISSN:0025-116X    

DOI:10.1002/macp.1966.020900104

出版商:Hüthig&Wepf Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractDurch Addition von (CH3)2SiHCl und CH3SiHCl2an die Beryllium‐ und Aluminium‐chelate des 4,4‐Diacetylbuten‐1 (Allylacetylaceton) ließen sich die entsprechenden siliciumfunktionellen Silylpropylchelate in hoher Reinheit und Ausbeute herstellen. Hydrolyse und Polykondensation führten im Falle des bifunktionellen Be‐Chelates zu linearen Polychelat‐siloxanen, die bei etwa 70°C erweichen, aber erst oberhalb 200°C schmelzen. Hydrolytische Polykondensation von tri‐, tetra‐ und hexafunktionellen Chlorsilylchelaten ergab vernetzte, pulverige Polymere; gleichzeitig trat in gewissem Umfang hydrolytische Spaltung de

ISSN:0025-116X    

DOI:10.1002/macp.1966.020900105

出版商:Hüthig&Wepf Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractIn this paper a mathematical treatment is developed for the developed for the calculation of the average percentage of right‐handed and left‐handed conformations of isotactic polymer chains having asymmetric side groups, all with the same optical sign, in unperturbed solution. This method derives the partition function of the infinite chains by a matrix formulation, allowing for neighbor interactions according to the ISING model; it leads to results which are in qualitative agreement with the experimental values of the optical rotation exhibited by polymer solutions at various temperatu

ISSN:0025-116X    

DOI:10.1002/macp.1966.020900106

出版商:Hüthig&Wepf Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractThe crystal structure of hexagonal polythiomethylene is described. It has a hexagonal unit cell with a = 5.07 Å. and c = 36.52 Å. The polymer chains are helicoidal with the axis of the helix parallel toc. In the unit cell are comprised 17 CH2Sunits and 9 turns of the

ISSN:0025-116X    

DOI:10.1002/macp.1966.020900107

出版商:Hüthig&Wepf Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractNEWTONian viscosities η of 4 poly(ethylene oxide)‐water systems were measured over the complete range of composition and at a number of different temperatures between 5 and 80°C. The molecular weights of the samples used ranged from 62.07 (glycol) up to 17,500. The temperature dependence of η varied with both composition and molecular weight and fitted very well an equation of the DOOLITTLE type, η = F(v2) exp[1/f(T,v2)], where f is the fractional free volume, F the statistical factor, and v2the volume fraction of the polymer solute. Values of f for each system evaluated as a function of T and v2varied nonlinearly with v2in all cases studied, giving curves convex downward. This behavior is similar to that found by OKADAet al. for methacrylate polymers in diethyl phthalate. Division of experimental values of η by exp[1/f(T,v2)] gives F as a function of v2, which was independent of temperature within experimental errors. The F's for the oligomers were not appreciably different from that for pure water, while the F's for the polymer fractions were much greater than that for pure

ISSN:0025-116X    

DOI:10.1002/macp.1966.020900108

出版商:Hüthig&Wepf Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractThe theory of the design and use of osmometers with semipermeable membranes is outlined with regard to rate of equilibration, zero‐errors due to temperature drift and leakage, and errors due to the formation of unstirred layers adjacent to the membrane. Some effects of these layers have been studied experimentally, and a brief review of the literature reveals some apparently unrecognized examples of similar phenomen

ISSN:0025-116X    

DOI:10.1002/macp.1966.020900109

出版商:Hüthig&Wepf Verlag    

年代:1966

数据来源: WILEY

摘要:

AbstractA transducer osmometer with the following characteristics is described: a sample volume of 0.5 ml. or less; avoidance of contact between solutions and metal; rapidity of equilibration; low surface tension correction; and high electrical stability. In each determination of an osmotic pressure the calibration of the transducer is established by making several rapid approaches to equilibrium by a method which avoids error due to the formation of unstirred layers. Sample results are given for bovine serum albumin.

ISSN:0025-116X    

DOI:10.1002/macp.1966.020900110

出版商:Hüthig&Wepf Verlag    

年代:1966

数据来源: WILEY