Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1985-1989  (3)
  • Polymer and Materials Science  (3)
  • theory of structure development
Source
Material
Years
Year
Keywords
  • Polymer and Materials Science  (3)
  • theory of structure development
  • Chemistry  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Acid curing of epoxy resins. A comparison between the polymerization of diepoxide-diacid and monoepoxide-cyclic anhydride systemsTo Professor R. Koningsveld on the occasion of his 60th birthday (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 2025-2036 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molar masses of linear polyesters formed in the polymerization of stoichiometric mixtures of 1,7-heptanedicarboxylic acid (4) with 2,2-bis[4-(2,3-epoxypropoxy)phenyl]propane (2) (the diglycidyl ether of Bisphenol A), and of 1,2-cyclohexanedicarboxylic anhydride (3) with 2,3-epoxypropyl phenyl ether (1), catalyzed with tertiary amines, and the effect of the concentration of the tertiary amine catalysts were compared. In the reaction between anhydride 3 and epoxide 1 the molar mass of polyester, determined by GPC, was found to decrease with increasing concentration of the tertiary amine, whereas in the reaction of the acid it is independent of the catalyst content. The molar mass distribution is much narrower in the reaction of the anhydride. These results correspond to the mechanisms determined earlier: a stepwise mechanism in the reaction between epoxide and acid, and an “initiation” mechanism in the case of anhydride. In the polymerization of the dicarboxylic acid 4 with the diepoxide 2 good agreement was observed with the theoretical dependences, calculated by using the theory of branching processes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021861006
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Effect of dilution during network formation on the sol fraction and elasticity of polyurethane networksDedicated to Prof. H.-J. Cantow for his contribution to polymer science on the occasion of his 65th birthday (1989)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 883-891 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of dilution at network formation (polymer volume fraction v(0) = 1 - 0,4) on the fraction and equilibrium photoelastic behaviour of polyurethane networks was investigated. The networks were prepared from poly(oxypropylene)triol and 4,4′-methylenedi(phenyl isocyanate) with various mole ratios of reactive groups 1 ≤ rH = [OH]/[NCO] ≤ 1,5. From a comparison between the experiments and the theory of branching processes we find that: (a) with both increasing ratio rH and increasing dilution the fraction of bonds lost in elastically inactive cycles increases from 0,02 to 0,06; (b) the experimental reduced equilibrium moduli Gr of the predominant majority of samples are higher than those theoretically predicted by the Flory junction-fluctuation theory for the front factor A = 1. Also the decrease of Gr with dilution (expressed as volume fraction of diluent during network formation v(0)) is very steep, thus supporting the contribution of permanent interchain constraints to the overall Gr value.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1989.021900421
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Curing of epoxides. Reaction of dicyanodiamide with phenylglycidyl ether (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 172 (1989), S. 185-194 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Härtung von Epoxidharzen mit dem latenten Härter 1-Cyanguanidin (Dicyandiamid) wurde anhand eines Modellsystems untersucht.Phenylglycidylether wurde mit 1-Cyanguanidin in Gegenwart von Benzyldimethylamin als Katalysator in einer Lösung von 2-Methoxyethanol umgesetzt. Die Kinetik der Reaktion wurde mit Hilfe der HPLC und der IR-Spektroskopie verfolgt. Einige der Reaktionsprodukte wurden durch semipräparative HPLC isoliert und identifiziert. Der Einfluß der Temperatur und des Anfangsverhältnisses der Reaktanden auf den Reaktionsmechanismus wurde untersucht. Es wurden 3 Teilreaktionen gefunden: a) Die Addition der Aminogruppe des 1-Cyanguanidins an die Epoxidgruppe, die dann die Reaktion der OH-Gruppen der Additionsprodukte mit b) der Nitrilgruppe oder c) mit dem Epoxid (Veretherung) einleitet. Die relativen Ausmaße der beiden letzteren Reaktionen nehmen mit dem Umsatz zu. Bei hohen Temperaturen ist die Reaktion der Nitrilgruppe bevorzugt, in Gegenwart von überschüssigem Epoxid der Reaktionsmischung dagegen, wenn die Veretherung vorherrscht, herabgesetzt.
    Notes: Curing of epoxy resins with the latent hardener 1-cyanoguanidine (dicyanodiamide) was studied using a model system. Phenylglycidyl ether was reacted with 1-cyanoguanidine in the presence of benzyldimethylamine as a catalyst in a solution in 2-methoxyethanol. The reaction kinetics was followed by means of HPLC and IR spectroscopy. Some of the reaction products were isolated by semipreparative HPLC and identified.The influence of temperature and of the initial ratio of reaction components on the reaction mechanism was studied. Three partial reactions were found: a) addition of the amino groups of 1-cyanoguanidine to the epoxide, which then initiates the reaction of OH groups of the addition products, b) with the C≡N group, or c) with the epoxide (etherification). The relative extents of the latter two reactions increase with conversion. The reaction of the nitrile group is preferred at high temperatures but depressed in the presence of excess epoxide in the reaction mixture when etherification prevails.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1989.051720116
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...