Cure kinetics of epoxy-based nanocomposites analyzed by Avrami theory of phase change

Abstract

The effect of montmorillonite on the cure kinetics and the structure of epoxy resin/organo-montmorillonite (Org-MMT)/methyltetrahydrophthalic anhydride (MeTHPA)/2-ethyl-4-methyl-imidazole (2,4-EMI) nanocomposites are investigated by X-ray diffraction (XRD) and the dynamic torsional vibration method (DTVM). The XRD result indicates that an exfoliated nanocomposite was obtained. The experimental data obtained from DTVM are explained by the Avrami theory of phase change, and show that the theoretical prediction is in good agreement with the experimental results. No special formation mechanism for epoxy resin/Org-MMT/MeTHPA/2,4-EMI nanocomposite is observed. The addition of Org-MMT reduces the gelation time t g, and increases the rate of the curing reaction and the value of the kinetic constant k. The half-time t 1/2 of cure after the gel point decreases with increasing cure temperature, while the values of kinetic constant k rise as the cure temperature increases. The nanocomposite has a larger value of k and smaller value of n comparing with the epoxy resin/MeTHPA/2,4-EMI system without Org-MMT.