Unlocking efficiency: Imidazole-nitrile based catalyst as latent thermal curative for improved epoxy resin curing and exploring mechanical behavior

Abstract

The imidazole core-based cyano-derivative (TDMN) was successfully synthesized through the reaction of terephthaldehyde and diaminomaleonitrile in absence of any catalysts with 86% yield. The product resulted was characterized for its molecular structure and cure behavior. TDMN was used for the curing of diglycidyl ether of bisphenol-A epoxy resin (E) with different amine curatives, including 4,4′-diaminodiphenylmethane (ddm), 4,4′-diaminodiphenylether (dde), 4,4′-diaminodiphenylsulfone (dds), dicyandiamide (dicy) and melamine (M). With a notable storage stability of 90 days, E-amines with TDMN proved strong and efficient. The curing temperatures were found to be 75°C, 120°C, 150°C, 150°C and 180°C for ddm, dde, dds, dicy and m based one-pack latent E-amines with TDMN, respectively. The activation energy (E_a) of E-M + TDMN has calculated using Kissinger and Ozawa methods and found that 80.14 kJ mol⁻¹ and 79.74 kJ mol⁻¹ respectively. Tensile specimens and bio-carbon briquettes fabricated using E-amines with TDMN catalyst exhibited enhanced tensile and compressive strength compared to neat E-amine systems. This study represents a pioneering development in latent thermal initiator technology for epoxy curing, with promising applications in composite fabrication and energy efficiency.