Synthesis and characterization of 1-(3-aminopropyl)imidazole-phenyl isocyanate adduct and its application as a thermal latent curing agent for diglycidylether bisphenol A resin

Official URL: https://dx.doi.org/10.1021/acsomega.4c03300

This study investigates the formulation and curing behavior of a one-component epoxy resin (OCER). The OCER was formulated using phenylurea propyl imidazole (PUPI) as a thermal latent curing agent and diglycidylether bisphenol A (DGEBA). PUPI was synthesized by reacting phenyl isocyanate with 1-(3-aminopropyl)imidazole and characterized using 1H NMR, Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). PUPI and DGEBA were mixed with a homogenizer at ambient temperature. Cure kinetics studies were conducted using DSC and a rheometer. The OCER achieved conversions of 97.6 and 99.3% at 120 and 140 °C in 5.17 and 1.95 min, respectively, and exhibited stability of 3 days at ambient temperature. Furthermore, PUPI acted as an accelerator for the dicyandiamide curing agent in the curing of DGEBA. Upon the incorporation of PUPI at various amounts (1, 5, and 10% by weight), the left-limit and peak temperatures of curing were significantly lowered from 173 and 204 °C to 72-111 °C and 122-155 °C, respectively.