摘要:

AbstractThe kinetics of the polymerization of methyl methacrylate initiated by lithium alkyls (tert‐butyllithium or ethyl α‐lithiobutyrate) was investigated in the presence of aluminium alkyls (triethylaluminium or triisobutylaluminium) in toluene at −78°C. The rate of polymerization decreases considerably once the living dimer is formed. This suggests that the aluminate end‐group coordinates with the penultimate ester group of the polymer chain, thus decreasing reactivity. The results are at variance with an activated monomer

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160601

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractMesoionic 5‐methyl‐4,6‐dioxo‐3‐phenyl‐1‐(4‐vinylphenyl)‐1,3‐diazine (5) was obtained by condensation of 3‐phenyl‐1‐(4‐vinylphenyl)formamidine (3) with methylmalonic acid (4). This vinyl‐substituted mesoionic heterocyclic compound was polymerized by usual radical initiation and, additionally, by thermally controlled polycycloaddition in solution, yielding two different types of polymers,6, 7. According to the X‐ray diffraction analysis, the structure of a low molecular weight model proves the regioselec

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160602

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractRheological and thermal analysis results of blends of a thermotropic copolyesteramide and polyarylate of bisphenol A depend on the thermo‐mechanical treatment during mixing. The changes observed as mixing time increases are the following: (a) melt viscosity and loss factor increase, (b) glass transition temperature decreases. The morphological analysis of the blends shows the inability of the treated blends to form an oriented liquid crystalline polymer (LCP) phase, which explains the observed viscoelastic propertie

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160603

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe choice of the photoinitiator is not usually regarded as being as important consideration in attempting to determine the value of the propagation rate coefficientkpfrom a pulsed laser‐initiated polymerization (PLP). It is shown that in fact the choice of the photoinitiator can profoundly influence the success of such experiments. Specially, for a number of monomers it was found that the successful determination ofkpis essentially impossible when 1,1‐azodicyclohexanecarbonitrile is employed as a photoinitiator. The likely reason for this phenomenon is discussed from which it would seem appropriate to be wary in using any azo compound as a PLP photoinitiator. From PLP experiments with a non‐azo photoinitiator, ambient pressurekphas been determined for bulk polymerization of methyl methacrylate over an extended temperature

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160604

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractA cross‐linked polysiloxane carrying non‐ionic amphiphilic side‐groups attached with their hydrophobic end to the polymer backbone is synthesized. The amphiphilic groups are selectively deuterated at the α‐position of the hydrophobic alkyl chains. The phase behavior with water is studied by deuterium nuclear magnetic resonance spectroscopy. A lamellar phase (La) is observed on the low‐water‐concentration side of the liquid‐crystalline regime. The domains of the La‐phase can be aligned macroscopically by uniaxial compressi

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160605

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractMethanol, in combination with a non‐ionic phosphazene base, was used to initiate the polymerization of octamethylcyclotetrasiloxane. In bulk, an instantaneous and large increase in viscosity was observed upon addition of the initiator. In toluene solution, the equilibrium state was reached in approximately 1 min. In addition to its high polymerization rate, another advantage of this system, as compared with e.g. alkali metal hydroxides, is that it is homogeneou

ISSN:1022-1336    

DOI:10.1002/marc.1995.030160606

出版商:Hüthig&Wepf Verlag    

年代:1995

数据来源: WILEY