Influence of Ionic Liquid in Sequential Trial‐Curable Off‐Stoichiometric Amine–Epoxy Thermosets on Curing Behavior, Thermal and Thermomechanical Properties

ABSTRACT The aim of this work was to develop and characterize sequential trial‐curable off‐stoichiometric thermosets based on two curing agents with different reactivities in terms of temperature. Trial‐curing refers to the occurrence of three curing reactions: epoxy‐amine polycondensation reaction triggered by polyetheramine D‐230 (reactive curing agent) at lower temperature, followed by adduct formation and anionic homopolymerization, both triggered by 1‐ethyl‐3‐methylimidazolium dicyanamide (latent curing agent) at higher temperature. Intermediate materials were studied after the first curing step. A wide range of properties such as reactivity, glass transition, network density, and thermal stability could be tuned by adjusting the relative contribution of the involved reactions. The glass transition of final samples, determined from the peak temperature of tan delta curve by Dynamic Mechanical Analysis, varied from 108.8°C to 166.4°C. This value increased by decreasing relative contribution of the epoxy‐amine condensation reaction. The curing process was additionally monitored by Fourier‐transformed infrared spectroscopy to identify curing reactions.