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  • 29Si NMR  (1)
  • epoxy resin  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 8 (1990), S. 235-239 
    ISSN: 1573-1111
    Keywords: Melanophlogite ; 29Si NMR ; phase transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 29Si MAS NMR spectra of natural melanophlogite as well as of synthetic melanophlogite indicate that the room temperature lattice structure has lower symmetry than expected from its proposed crystal structure. On heating the samples to temperatures above room temperature, the structure undergoes a reversible phase transition with a transition temperature characteristic of the locality. For the synthetic melanophlogite, the transition is over the range 298 K to 338 K. From low temperature NMR spectra it is concluded that the low temperature forms of synthetic melanophlogite and of melanophlogite from Sicily differ in their crystal lattice symmetries due to their characteristic guest species.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1191-1202 
    ISSN: 0887-624X
    Keywords: crosslinking agents ; cyanate resin ; epoxy resin ; polyolefin ; 13C-NMR ; 15N-NMR ; 1H-NMR ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An efficient crosslinking monomer for a mixed cyanate/epoxy resin system, bisphenol-A-monocyanate monoglycidyl ether 3, has been synthesized and characterized. The intermediate compound, the monoglycidyl ether of bisphenol-A 2, was also isolated and purified by extraction and chromatographic separation using a silica gel column. The cyanate functional group in the crosslinking monomer 3 can be cured easily by heat to form a triazine structure 8, but the epoxy functional group in the crosslinking monomer 3 can not be cured without affecting the cyanate group because the latter is more reactive both under heat and basic conditions. A practical approach for the application of the crosslinking monomer 3 is discussed and tested. Most interestingly, under heat curing, a very tough and strong resin material was produced from this crosslinking mixed resin mixture. By using a secondary amine, diethylamine, as a curing agent, the cyanate groups in the crosslinking monomer 3 react to form the structures 11 or 12, depending on the molar ratio of monomer 3 to diethylamine. A bifunctional crosslinking agent for a mixed cyanate (thermoset) and polyolefin (thermoplastic) resin system, 2-allylphenyl cyanate 16, has also been synthesized and characterized. Like 3, 2-allylphenyl cyanate 16 easily forms the crosslinking triazine compound 17 upon heating. 17 is a crystalline solid with mp = 110-111°C. As a crosslinking agent, 2-allylphenyl cyanate 16 reacts not only with itself, but also with other cyanates to form heterogeneous triazine rings, exemplified by triazines 18 and 19. Even though it does not self polymerize through the allyl double bond, it can copolymerize with an other olefinic monomer, such as methyl methacrylate, to form a crosslinked and insoluble polymer. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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