Super‐crosslinked ionic liquid‐intercalated montmorillonite/epoxy nanocomposites: Cure kinetics, viscoelastic behavior and thermal degradation mechanism

Abstract

AbstractSuper‐crosslinked epoxy nanocomposites containing N‐octadecyl‐N′‐octadecyl imidazolium iodide (IM)‐functionalized montmorillonite (MMT‐IM) nanoplatelets were developed and examined for cure kinetics, viscoelastic behavior and thermal degradation kinetics. The structure and morphology of MMT‐IM were characterized by FTIR, XRD, TEM, and TGA. Synthesized MMT‐IM revealed synergistic effects on the network formation, the glass transition temperature (Tg) and thermal stability of epoxy. Cure and viscoelastic behaviors of epoxy nanocomposites containing 0.1 wt% MMT and MMT‐IM were compared based on DSC and DMA, respectively. Activation energy profile as a function of the extent of cure was obtained. DMA results indicated a strong interface between imidazole groups of MMT‐IM and epoxy, which caused a significant improvement in storage modulus and the Tg of epoxy. Network degradation kinetics of epoxy containing 0.5, 2.0, and 5.0 wt% MMT and MMT‐IM were compared by using Friedman, Kissinger‐Akahira‐Sunose (KAS), Flynn‐Wall‐Ozawa (FWO) and the modified Coats‐Redfern methods. Although addition of MMT to epoxy was detrimental to the Tg value, as featured by a fall from 94.1°C to 89.7°C detected by DMA method, and from 103.3°C to 97.9°C by DSC method, respectively. By contrast, meaningful increase in such values were observed in the same order from 94.1°C to 94.7°C and from 103.3°C to 104.7°C for super‐crosslinked epoxy/MMT‐IM systems.