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  • Chemistry  (18)
  • Polymer and Materials Science  (17)
  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    The effect of crosslinking on properties of polyurethane elastomers (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 391-398 
    Details
    ISSN: 0021-8995
    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
    Notes: A series of segmented polyurethanes from two polyols, 4,4′-diphenylmethane diisocyanate (MDI) and butane diol was synthesized. The degree of chemical crosslinking was controlled by varying the ratio of poly(oxypropylene) diol to poly(oxypropylene/oxyethylene) triol. The samples were prepared at the stoichiometric ratio of NCO to OH groups and at a constant concentration of hard segments (butane diol; MDI) equal 50 wt %. At low concentrations of the triol the molecular weight of the polyurethanes increases; at higher concentrations (above 9 mol %) crosslinked products are obtained. All samples show a distinct two-phase structure and in the region of 0-150°C the dynamic mechanical behavior is affected by the hard phase. Chemical crosslinking was found to increase the tensile strength and strain at break, but did not affect appreciably the tear strength, hardness, and soft segment glass transition. The stress relaxation rate at room temperature was found to depend both on the elongation and on the degree of crosslinking. A comparison of the sol fractions ws found for crosslinked samples with the predictions of the theory of branching processes proved that the achieved conversions of reactive groups in networks are high (∼ 0.98).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420211
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  • 5
    Electronic Resource
    Electronic Resource
    Cyclotrimerization of isocyanate groups. I. Catalyzed reactions of phenyl isocyanate (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 895-904 
    Details
    ISSN: 0021-8995
    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
    Notes: Cyclotrimerization of phenyl isocyanate in the presence of various catalysts was studied. All reactions were carried out in 1,4-dioxane at 30-50°C. Reaction products were determined by reverse-phase liquid chromatography. 1,3,5-Triphenyl isocyanurate was formed and also traces of 1,3-diphenylurea and 1,3,5-triphenylbiuret were found. The catalytic activity decreased in the following series: quaternary ammonium salt 〉 organic acid salt ≫ tertiary amine. Apparent rate constants of cyclotrimerization were calculated and the overall reaction order is discussed. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070520708
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  • 6
    Electronic Resource
    Electronic Resource
    Cyclotrimerization of isocyanate groups. II. Catalyzed reactions of phenyl isocyanate in the presence of 1-butanol or butyl-N-phenylurethane (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 53 (1994), S. 1435-1446 
    Details
    ISSN: 0021-8995
    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
    Notes: Cyclotrimerization of phenyl isocyanate at 30-50°C in the presence of 1-butanol or butyl-N-phenylurethane and catalysts of tertiary amine, quaternary ammonium salt, or carboxylate types in 1,4-dioxane was studied by reverse-phase liquid chromatography. Urethane, allophanate, urea, biuret, isocyanurate, and isocyanate model compounds were found in the system. Stability of all reaction products was also examined. The time dependence of evolution of various products depends on the catalyst type and temperature. The overall reaction scheme was proposed. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070531105
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  • 7
    Electronic Resource
    Electronic Resource
    Problems of structural characterization of polymer networks (1979)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 246-253 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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
    Notes: Problems of the characterization of network structure by investigating the network formation and its response to mechanical stress have been analyzed. Attention has been devoted to the effect of reactivity of functional groups and cyclization on the formation of network structure and to problems of obtaining the equilibrium modulus and its relation to the concentration of elastically active network chains (EANCs). It has been demonstrated that a theoretical description of network formation must be based on reliable information on the rules of joining of functional groups and on their relative reactivity; the tree-like approximation offers a number of structural parameters of the sol and gel including, e.g, chemical clustering of units of a certain type. The main obstacles to reaching the equilibrium modulus are long relaxation, times of lightly crosslinked networks and the occurrence of secondary relaxations. In correlating the equilibrium modulus and the concentration of EANCs, it is necessary to find conditions under which the Mooney-Rivlin constant C2 can be neglected and to carry out the required corrections of the modulus, if experimental conditions differ from those of network formation.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760190404
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  • 8
    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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  • 9
    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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  • 10
    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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