Artículos de revistas
Kinetics of the epoxy-thiol click reaction initiated by a tertiary amine: Calorimetric study using monofunctional components
Fecha
2015-08-08Registro en:
Meizoso Loureiro, Roi; Carballeira Amareloa, Tánia ; Paz Abuin, Senen; Soulé, Ezequiel Rodolfo; Williams, Roberto Juan Jose; Kinetics of the epoxy-thiol click reaction initiated by a tertiary amine: Calorimetric study using monofunctional components; Elsevier Science; Thermochimica Acta; 616; 8-8-2015; 79-86
0040-6031
Autor
Meizoso Loureiro, Roi
Carballeira Amareloa, Tánia
Paz Abuin, Senen
Soulé, Ezequiel Rodolfo
Williams, Roberto Juan Jose
Resumen
An analysis of the kinetics of the epoxy–thiol reaction in a model stoichiometric system of monofunctional reagents, 3-mercaptopropionate (BMP) and phenylglycidylether (PGE) is reported. Benzyldimethylamine (BDMA) was employed as initiator in amounts ranging from 0.5 to 2 wt%. These formulations showed a kinetic behavior qualitatively similar to that of commercial adhesives and coatings formulated for a room-temperature cure. Isothermal DSC scans revealed the existence of a relatively long induction period preceding a fast autocatalytic reaction step. Dynamic DSC scans showed that the reaction was shifted to a lower temperature range by increasing the storage period of the initial formulation at 20 °C. This unusual kinetic behavior could be modeled assuming that thiolate anions, slowly generated during the induction period, initiated a fast autocatalytic propagation/proton transfer reaction. The kinetic model included a pseudo-steady state for the initiator concentration and an equilibrium reaction between epoxy and OH groups generated by reaction. A reasonable fitting of isothermal and dynamic DSC runs was achieved in a broad range of temperatures and amine concentrations. In particular, both the length of the induction time and the effect of the storage period were correctly predicted.