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  • 1
    Electronic Resource
    Electronic Resource
    Antioxidants and stabilizers (1990)
    Springer
    Polymer bulletin 24 (1990), S. 309-312 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary 2,6-Ditert-butyl-4-methyl-4-(3,5-ditert-butyl-4-hydroxybenzyl)-2,5-cyclohexadiene-1-one (III) is formed from BHT (I) as a minority transformation product during the ageing of BHT doped polyethylene. To determine the structure of III and to obtain an authentic model compound, synthesis was performed using an indepdndent procedure. The transformation product III is reported for the first time and can be considered as a source of secondary phenoxy radicals detected in aged polyolefins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306580
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  • 2
    Electronic Resource
    Electronic Resource
    Anionic polymerization of acrylates. II. Polymerization of 2-ethylhexyl acrylate initiated by butyllithium/lithium-tert-butoxide system in tetrahydrofuran and its mixtures with tolueneFor Part I, see Reference 7. (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1511-1518 
    Details
    ISSN: 0887-624X
    Keywords: polymerization anionic ; acrylates ; complex initiators ; 2-ethylhexylacrylate ; tert-alkoxides ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The anionic polymerization of 2-ethylhexyl acrylate (EtHA) initiated with the complex butyllithium/lithium-tert-butoxide (BuLi/t-BuOLi) was investigated at -60°C in a medium of various solvating power, i.e., in mixtures of toluene and tetrahydrofuran and in neat tetrahydrofuran. With increasing amount of THF in the mixture the attainable limiting conversion of polymerization decreases; the monomer can be polymerized quantitatively only in a toluene/THF mixture (9/1). Molecular weights of the polymers thus obtained, their distribution, and initiator efficiency are not appreciably affected by the polymerization medium. The molecular weight distribution of the products is medium-broad (Mw/Mn = 2-2.4), with a hint of bimodality. The 1H-13C-NMR, and IR spectra suggest that during the polymerization there is neither any perceptible reesterification of the polymer with the alkoxide nor transmetalation of the monomer with the initiator. In a suitable medium, autotermination of propagation proceeds to a limited extent only, predominantly via intramolecular cyclization of propagating chains; in a medium with a higher content of polar THF, it prevails and terminates propagation before the polymerization of the monomer has been completed. © 1992 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300801
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  • 3
    Electronic Resource
    Electronic Resource
    Separation of alkylnaphthalenes by preparative liquid chromatography using column switching systems (1990)
    Springer
    Chromatographia 29 (1990), S. 366-374 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Preparative scale separation ; Column coupling and column switching ; GC analysis of fractions ; Diaromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper describes the separation of the mixture of alkynaphthalenes from distillation cuts of a pyrolysis oil, by preparative liquid chromatography on silica. The design of the system permits the connection of the columns to form multicolumn systems. The samples were first separated on a single column. The mixtures were further separated using two-column chromatography systems. The obtained fractions were analyzed by capillary gas chromatography. In most cases a substantial increase in the concentrations of the individual components was achieved. In several cases, pure compounds have been obtained. Separation efficiency increases in the following order: single column, two directly coupled collumns, two-step switching chromatography, heartcutting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261305
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  • 4
    Electronic Resource
    Electronic Resource
    NMR study of the propagation center in cationic polymerization of N-benzoyl-8-octanelactam. I. The structure of model living oligomers (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1705-1711 
    Details
    ISSN: 0887-6266
    Keywords: nuclear magnetic resonance (NMR) of model living oligomers ; cationic po-lymerization of N-substituted lactam propagation center of ; N-benzoyl-8-octanelactam, propagation center in cationic polymerization of ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Model living oligomers of N-benzoyl-8-octanelactam initiated by the model octanoylium hexachloroantimonate, SbCl5, and by Ph3C+ AsF6-, were studied by 1H and 13C one- and two-dimensional nuclear magnetic resonance using the COSY, S-INEPT, COLOC, and ROESY methods. If prepared in the more solvating mixture of 1,1,2,2-tetrachloroethane (TCE) with 1,2-dichlorobenzene, the oligomers were found to be linear with the acylium ion as a living group on one end; in TCE only, the oligomers are highly branched. In both cases, the propagation center appears to be strongly coordinated to the nearest benzoylamide chain group. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090311206
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  • 5
    Electronic Resource
    Electronic Resource
    NMR Study of the propagation center in the cationic polymerization of N-benzoyl-8-octanelactam. II. Investigation of the propagation center (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 1129-1136 
    Details
    ISSN: 0887-6266
    Keywords: NMR ; cationic polymerization ; lactams ; polymerization mechanism ; carbenium ions ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nature of the propagation center in the cationic polymerization of N-benzoyl-8-octanelactam initiated by octanoylium hexachlcroantimonate, SbCl5, and Ph3CAsF6 in perdeuterated tetrachloroethane or its mixture with o-dichlorobenzene was studied using 1H, 13C, 19F, 31P, 75As, and 121Sb nuclear magnetic resonance (NMR) of model oligomers and the products of their end-capping with triphenylphosphine. In all cases, the nature of the propagation center has been found to be of an acylium ion pair with an SbCl6- or AsF6- counterion coordinated with the nearest benzoylamide group and cosolvated by the solvent. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090320617
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