Abstract
Summary: The curing reaction kinetics and mechanism of the diglycidyl ether of bisphenol A (DGEBA) with three complexes of Ni(II) with diethylentriamine (Dien), Pyrazole (Pz) and Pyridine (Py) as ligands have been studied using differential scanning calorimetry (DSC). The curing reaction was characterized by high cure onset and peak maximum temperatures. The kinetics of the curing reaction were evaluated using the Ozawa method. The average values of activation energy for the three nickel complexes increased in the order: Dienโbased curing agentโ>โPzโbased curing agentโ>โPyโbased curing agent. Three main curing mechanisms (catalytic, complex cation and free ligand polymerization path) have been proposed depending on the cure temperature. It was also shown that the cure kinetics of DGEBA with Dienโ and Pyโbased complexes could be described by the SestakโBerggren equation. The water absorption, chemical resistance and thermal stability of the thermosets were also studied. The results showed that the thermoset obtained with the Pyโbased complex was more thermally stable than those obtained with the other two curing agents.
Activation energy versus conversion plots for the epoxy systems studied.
imageActivation energy versus conversion plots for the epoxy systems studied.