The Effect of Molecular Weight of Resin on Cure Kinetics of Epoxy/ Diaminodiphenylmethane

Epoxy resins are among the most versatile thermosetting systems, because of their outstanding properties and wide range applications. In thermosetting systems, the kinetic characterization usually required to understand structure-property-processing relationships for the material manufacturing and utilization. The curing behavior and kinetics of liquid epoxy resin with diaminodiphenylmethane (DDM) as the curing agent was studied by many researchers. But there is no any report on the kinetics of solid epoxy systems. Therefore, in this work the curing kinetics of epoxy resins with various molecular weights (i.e. 380 and 1400 g mol-1) was elucidated by non-isothermal Differential Scanning Calorimetry (DSC). The experimental results have been investigated by model free kinetics. The results showed that the activation energy of liquid epoxy/DDM was in the range of 48±2 kJ/mol and might be considered to be constant during the curing. But the activation energy of the solid epoxy system increased steadily with the conversion, especially in the later stages (α > 0.6).