Carbonyldiimidazole‐accelerated efficient cure of epoxidized soybean oil with dicyandiamide

Abstract

This study investigates the curing of epoxidized soybean oil (ESO) using dicyandiamide (DICY) and combinations of DICY with several accelerators as curing agents. The differential scanning calorimetry (DSC) results indicated that carbonyldiimidazole (CDI) is a highly efficient accelerator for the ESO‐DICY curing system. CDI accelerated ESO‐DICY curing system can gel within a short period of 13 min at 190 °C. The activation energies of the ESO‐DICY curing systems with and without CDI are 95 and 121 kJ mol−1, respectively. Similar acceleration effect was observed in the ESO‐diglycidyl ether of biphenyl A (DGEBA) blending formulations. When the molar part of the glycidyl epoxy groups of DGEBA was equal to the internal epoxy groups of ESO in the mixture, gelation of the DICY curing system accelerated by CDI was achieved in 3 min at 160 °C. Furthermore, the DSC results with FTIR analysis suggest that the stoichiometric curing molar ratio was 3 ESO epoxy units per 1 DICY molecule. Two epoxy units reacted with DICY to give secondary alcohols, while the other one linked to the nitrile group. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 375–382

Reaction mechanism, cure behavior and properties of a multifunctional epoxy resin, TGDDM, with latent curing agent dicyandiamide

“…For these reasons, DICY is resoundingly used as a thermally latent curing agent for epoxy resins in laminates, prepregs, coatings and adhesives. [15][16][17] Generally, the nal properties of the cured epoxy materials are determined mainly by the network macromolecular structures and morphology, which depend on the type of cure reaction and the stage that it takes place during the curing process. 18,19 Therefore, it is imperative to study the reaction mechanism and curing behaviors of epoxy systems.…”

A study of the mechanism of curing of the dicyandiamide-epoxydiane oligomer system in the presence of asymmetrical urea

“…Recent research by a group of Japanese scientists [28,29] has been devoted to working out of the self catalytic mechanism of curing of the epoxide-dicyan diamide system in combination with different acceler ators-derivatives of urea and carbonyldiimidazole. Experimental results obtained by DSC, TGA, and DTA NMR spectroscopy showed that, when a number of N aryl N',N' dialkyl ureas are used upon thermal dissociation, urea releases a corresponding secondary amine in the presence of epoxide groups with the for mation of tertiary amines, which catalyze the reaction of interaction of DCDA and epoxy oligomers.…”

Bio-Based Epoxy Resin from Epoxidized Soybean Oil

“…Due to this fact, the reported curing processes of ESO usually needs higher temperature and longer time than commercial petroleum-based epoxy resin, such as bisphenol A epoxy resin. However, the combination of the hardener, dicyandiamide (DICY), and the accelerator, carbonyldiimidazole (CDI), can make the gelation of ESO occur within 13 min at 190°C [20]. Moreover, the gelation of the mixture of ESO and DGEBA is achieved with the aid of DICY and CDI within 3 min at 160°C [20].…”

“…However, the combination of the hardener, dicyandiamide (DICY), and the accelerator, carbonyldiimidazole (CDI), can make the gelation of ESO occur within 13 min at 190°C [20]. Moreover, the gelation of the mixture of ESO and DGEBA is achieved with the aid of DICY and CDI within 3 min at 160°C [20]. Fully or high bio-based polymers are also attractive to researchers owing to people's strong attention to environment concerns.…”