Isothermal Cure of an Epoxy System Containing Tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM), a Multifunctional Novolac Glycidyl Ether and 4,4′-Diaminodiphenylsulphone (DDS): Vitrification and Gelation |
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Authors: | L Barral J Cano J Lpez P Nogueira C Ramírez M J Abad |
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Abstract: | Times to gelation and vitrification have been determined at different isothermal curing temperatures between 200 and 240°C for an epoxy/amine system containing both tetraglycidyl-4,4′-diaminodiphenylmethane (TGDDM) and a multifunctional Novolac glycidyl ether with 4,4′-diaminodiphenylsulphone (DDS). The mixture was rich in epoxy, with an amine/epoxide ratio of 0·64. Gelation occurred around 44% conversion. Vitrification was determined from data curves of glass transition temperature, Tg, versus curing time obtained from differential scanning calorimetry experiments. The minimum and maximum values Tg determined for this epoxy system were Tg0=12°C and Tgmax=242°C. Values of activation energy for the cure reaction were obtained from Tg versus time shift factors, aT, and gel time measurements. These values were, respectively, 76·2kJmol-1 and 61·0kJmol-1. The isothermal time–temperature–transformation (TTT) diagram for this system has been established. Vitrification and gelation curves cross at a cure temperature of 102°C, which corresponds to glass transition temperature of the gel. © of SCI. |
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Keywords: | TGDDM epoxy DSC vitrification gelation time– temperature– transformation (TTT) diagram |
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