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  • 1
    Electronic Resource
    Electronic Resource
    Electrophilic aromatic substitution in the curing of brominated poly(isobutylene-co-4-methylstyrene): A mechanistic model study with zinc salts (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 755-762 
    Details
    ISSN: 0887-624X
    Keywords: brominated poly(isobutylene-co-4-methylstyrene) ; electrophilic crosslinking ; elastomer ; Friedel-Crafts mechanism ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crosslinking chemistry of a new elastomer based on brominated poly(isobutylene-co-4-methylstyrene) has been investigated using model compounds. In order to mimic the conditions that prevail within the highly allphatic rubber, the study was carried out in mineral oil using catalysts that are compatible with such low polarity media. Electrophilic aromatic substitution reactions occur in a system consisting of p-isopropylbenzyl bromide and p-isopropyl toluene in the presence of zinc oxide and zinc stearate. The reaction proceeds after a significant induction period while no induction period is seen for a similar reaction with zinc bromide as the catalyst. The in situ formation of reactive species containing Zn—Br bonds appears to be an important step in the overall process. The stoichiometric ratio of zinc salt to benzylic bromide is important. High ratios lead to the accumulation of benzylic stearate or benzylic alcohol in the system which retards the alkylation reaction. The model study emphasizes the importance of stoichiometry of reagents in this reaction and provides insight into the crosslinking mechanism. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310321
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    TWO-DIMENSIONAL ELASTODYNAMIC TRANSIENT ANALYSIS BY QL TIME-DOMAIN BEM FORMULATION (1996)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 951-985 
    Details
    ISSN: 0029-5981
    Keywords: time-domainBEM ; 2-D convoluted kernel ; transient wave ; quadratic temporal variation ; elastodynamics ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A quadratic time-domain Boundary Element Method (BEM) for two-dimensional (2-D) elastodynamic transient wave analysis is presented. Emphasis is focused on developing time-domain fundamental convoluted kernels and methodology for quadratic temporal solution procedure which are never presented before. In the presented BEM method, the displacement temporal variation is assumed to be quadratic, the traction temporal variation is assumed to be linear (called QL method, a two-time-step piecewise continuity method), and the spatial variations are assumed to be quadratic variation. The QL method is compared with the LC method and the QC method by solving several example problems. Numerical study reveals that the QC and QL methods are more accurate and stable than the LC method, and the QL method is much better than the QC method for transient problems.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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