Thermodynamic analysis of the reaction-induced phase separation in model systems based on blends of a rubber in diepoxide / monoamine precursors |
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Authors: | Ileana A Zucchi María J Galante Julio Borrajo Roberto JJ Williams |
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Institution: | Institute of Materials Science and Technology (INTEMA), University of Mar del Plata-National Research Council (CONICET). J. B. Justo 4302, 7600 Mar del Plata, Argentina |
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Abstract: | The reaction-induced phase separation in blends based on a carboxyl-terminated poly(butadiene-co-acrylonitrile) rubber (CTBN), dissolved in diglycidyl ether of bisphenol A (DGEBA) - benzylamine (BA) monomers, was studied. The polymerization kinetics was followed by size exclusion chromatography, for both the neat DGEBA-BA system and for blends containing 10 wt% CTBN. No effect of CTBN addition on the polymerization rate was observed within experimental error. The kinetics could be fitted with a model based on the presence of non-catalytic and OH-catalyzed reactions and assuming equal reactivity of primary and secondary amine hydrogens. Cloud-point conversions were determined at 60, 70 and 80 °C. The Flory-Huggins model provided a reasonable fitting of experimental data using an interaction parameter depending exclusively on temperature, and taking polydispersities of both linear polymers into account. Linear epoxy/amine systems may be used to test the reliability of thermodynamic theories in more complex situations (e.g., modifiers with a broad distribution of molar masses or mixtures of several modifiers). |
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Keywords: | cloud point conversion kinetics phase separation |
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