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  • 1
    Electronic Resource
    Electronic Resource
    Are cured thermoset resins inhomogeneous?Lecture presented at International Symposium on Advanced Network-Polymers, Kansai University (ISANKU), at Kansai University, Suita, Osaka, Japan, on December 5-6, 1995 (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 1-15 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This question was addressed using various methods to monitor the process of curing and state of the final network. Attention was particularly focused on the possible inhomogeneous network formation as a consequence of the crosslinking process. An analysis of experimental data has revealed that some cured resins can be considered as homogeneous as the corresponding uncrosslinked materials. Resins cured by simple stepwise alternating chemistries, with good compatibility of components, usually fulfill the criterion of homogeneity. A family of epoxy resins cured with polyamines belongs to this category. Nodular structures seen by electron microscopy are a result of interaction of the electron beam or etching. Such structures are also observed for uncrosslinked polymers investigated under the same conditions. Formation of inhomogeneities in a number of thermoset systems is due to (a) chainwise mechanism of network formation with fast propagation inducing cyclization and steric volume exclusion and (b) poor compatibility of components of the system made stronger by increasing molecular weights and crosslinking during curing. Networks formed by freeradical polymerization and copolymerization of polyvinyl monomers can serve as an example of crosslinking-driven formation of inhomogeneities.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052400101
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  • 2
    Electronic Resource
    Electronic Resource
    Crosslinking and networks (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 2 (1979), S. 35-49 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Theoretical treatments of network formation and the applicability of the tree-like models to the calculation of structural parameters in the post-gel state and to more complex systems of practical importance are discussed. The unseparability of structural interpretation of network properties from network formation is stressed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.020021979103
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamic and static light scattering from critically branched polymer solutionsDedicated to Professor H. Inagaki on the occasion of his 60th birthday (1984)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 185 (1984), S. 2543-2552 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Critically branched polyurethanes of varying molecular weight were prepared from poly(oxypropylene)triol and methylenedi-p-phenylene diisocyanate with and without solvent. The static/dynamic light scattering from DMF solutions of these samples was measured. The results were discussed in terms of the classical (Flory-Stockmayer, FS) and percolation theory of gelation; the bulk-polymerized sample obeyed the FS process, whereas the solution-polymerized samples were better described by the percolation process.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1984.021851207
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  • 4
    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
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  • 5
    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
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  • 6
    Electronic Resource
    Electronic Resource
    Curing of diglycidylamine-based epoxides with amines: Kinetic model and simulation of structure development (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 461-472 
    Details
    ISSN: 0887-624X
    Keywords: reaction mechanism ; curing of epoxides ; theory of structure development ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A complex mechanism of the reaction of diglycidylamine (DGA)-based epoxides with primary amines is described and the kinetic model is developed. The reaction mechanism involves the addition of amine, etherification, and also formation of small cycles and anionic homopolymerization of the epoxide compound including transfer and termination. The polymer structure was theoretically described by distribution of structural fragments determined using the kinetic model. Simulation of the structure evolution during the DGA-aniline reaction at varying molar ratios of reagents and dilution of the system was performed. The effect of the reaction conditions on the distribution of structural fragments, such as branching units and cyclic structures, was determined. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330313
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  • 7
    Electronic Resource
    Electronic Resource
    Differences in structure growth in amine curing of diglycidyl ether of bisphenol a and N,N-diglycidylaniline epoxy resins: Bifunctional models (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 473-480 
    Details
    ISSN: 0887-624X
    Keywords: epoxides ; reaction mechanism ; cyclization ; structure development ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of diepoxides, diglycidylaniline (DGA), or diglycidyl ether of Bisphenol A (DGEBA) with aniline was followed using HPLC and SEC. The effect of molar ratio of reagents, dilution of the system, reaction temperature, and the difference between the reaction mechanisms for DGA and DGEBA systems on the reaction kinetics and molecular weight evolution is discussed. Molecular weights of the DGA-aniline polymers were by an order of magnitude lower than those of the DGEBA-aniline polymers due to the formation of small cyclic products in the former case. Also, a reduction in Mn with increasing temperature, dilution, and diluent polarity is brought about by a greater tendency toward cyclization under these conditions. Theoretically calculated molecular weight evolution during the reaction is in satisfactory agreement with the experiment. © 1995 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330314
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  • 8
    Electronic Resource
    Electronic Resource
    Model reactions of amine curing of glycidylamine epoxy resins: Homopolymerization of N-methylglycidylaniline (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2109-2120 
    Details
    ISSN: 0887-624X
    Keywords: epoxide ; reaction mechanism ; kinetics ; homopolymerization of epoxides ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of homopolymerization of the monofunctional epoxide N-methylglycidylaniline in the presence of a tertiary amine or an amino alcohol has been followed by reversed phase high performance liquid chromatography and size exclusion chromatography. The reaction products were identified by mass spectrometry using potassium ionization of desorbed species (K+IDS). 1,3-Di-N-methylanilino-2-propanol (P) was the main reaction product and low molecular weight oligomers with Mn 〉 600 were also formed. The molecular weight and fraction of oligomers decrease with increasing concentration of the initiator. The suggested complex reaction mechanism involves formation of four stable oligomeric series initiated by reaction of the epoxide with either an OH group of (a) the amino alcohol, (b) product P, (c) traces of water, or (d) the tertiary amine to form ionic species resulting in the ionic propagation. Regeneration of the initiator and formation of new initiating centers during the polymerization are the causes of low molecular weights of oligomers. © 1992 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301004
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  • 9
    Electronic Resource
    Electronic Resource
    Concise encyclopedia of polymer processing and applications. Edited by Patrick K. Corish, Pergamon, Oxford 1991, 772 pp., hardcover, £ 140, ISBN 0-08-037064-0 (1993)
    Weinheim : Wiley-Blackwell
    Advanced Materials 5 (1993), S. 64-64 
    Details
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19930050118
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  • 10
    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
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