FTIR/ATR study of the copolymerization of diglycidyl ether of Bisphenol A with methyl-substituted γ-lactones catalyzed by rare earth triflate initiators |
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| Authors: | Mercè Arasa Xavier Ramis Josep Maria Salla Ana Mantecón Angels Serra |
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| Institution: | 1. Departament de Química Analítica i Química Orgànica, Universitat Rovira i Virgili, C/Marcel·lí Domingo s/n, 43007 Tarragona, Spain;2. Departament de Màquines i Motors Tèrmics, Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona, Spain |
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| Abstract: | Mixtures of DGEBA with γ-valerolactone (γ-VL) or α-methyl-γ-butyrolactone (γ-MBL) 2:1 (mol/mol) were cationically copolymerized in the presence of scandium, ytterbium, or lanthanum triflates as initiators. The evolution of the different reactive groups was followed by means of FTIR/ATR spectroscopy. From these experiments, we could detect the coexistence of two unexpected processes: a reversion of the intermediate spiroorthoester formed to the initial products and a depolymerization process, which only takes place in samples with γ-VL, when scandium triflate was used as initiator or when the proportion of ytterbium triflate was increased from 1 to 3 phr. When γ-MBL was used as comonomer no depolymerization occurs which supports the proposed mechanism. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2129–2141, 2007 |
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| Keywords: | cationic polymerization copolymerization crosslinking epoxy resins FT-IR lactones lanthanide triflates shrinkage thermosets |
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