ORS2-0196
Effect of DICY Content on the Network Structure and Mechanical Properties of Epoxy Resins
Topic
S2. High-End Characterization/Polymer Physics/Properties
When and Where
Sep 29, 2026
16:15 - 16:30
Room 103
Session Chairs
Eunji LEE
Presenter(s)
Rika Marui (Kyushu University)
Co-Author(s)
Abstract
Epoxy resins are formed through curing reactions between an epoxy base and a curing agent, resulting in a cross-linked network structure. Among various curing agents reported so far, dicyandiamide (DICY) has attracted considerable attention due to its excellent storage stability and ease of handling. To confer desirable properties onto epoxy resins, it is essential to understand the relationship between their network structure and mechanical properties. However, since DICY undergoes multiple reaction pathways and its reactivity depends strongly on curing conditions, the relationship is complex and not yet fully understood. In this study, we aim to understand the structure−properties relationship for epoxy resins cured with different DICY contents.
Diglycidyl ether of bisphenol A (DGEBA) and DICY were used as the epoxy base and curing agent, respectively. DGEBA and DICY were mixed at different molar ratios (φ) of 0.10, 0.13 and 0.14. The mixtures were pre-cured at 453 K for 12 h and post-cured at 503 K for 12 h. Fourier-transform infrared (FT-IR) spectroscopy confirmed that for all cured resins, epoxy groups were completely consumed. Both the cross-linking and mass densities of the cured epoxy resins were independent of φ. Tensile tests conducted at room temperature revealed that increasing φ resulted in an increase in Young's modulus (E) and a decrease in fracture energy (Gf). FT-IR analysis further showed that the fraction of urethane bonds, which form hydrogen-bonding, increased with increasing φ. Given that the cross-linking and mass densities remained unchanged, the increase in E is most likely attributable to the increased fraction of hydrogen-bonding interactions. In contrast, the decrease in Gf cannot be simply explained in terms of the formation of urethane bonds. In the presentation, we will further discuss the network structure and dynamic heterogeneity to address the origin of the decrease in Gf.
Diglycidyl ether of bisphenol A (DGEBA) and DICY were used as the epoxy base and curing agent, respectively. DGEBA and DICY were mixed at different molar ratios (φ) of 0.10, 0.13 and 0.14. The mixtures were pre-cured at 453 K for 12 h and post-cured at 503 K for 12 h. Fourier-transform infrared (FT-IR) spectroscopy confirmed that for all cured resins, epoxy groups were completely consumed. Both the cross-linking and mass densities of the cured epoxy resins were independent of φ. Tensile tests conducted at room temperature revealed that increasing φ resulted in an increase in Young's modulus (E) and a decrease in fracture energy (Gf). FT-IR analysis further showed that the fraction of urethane bonds, which form hydrogen-bonding, increased with increasing φ. Given that the cross-linking and mass densities remained unchanged, the increase in E is most likely attributable to the increased fraction of hydrogen-bonding interactions. In contrast, the decrease in Gf cannot be simply explained in terms of the formation of urethane bonds. In the presentation, we will further discuss the network structure and dynamic heterogeneity to address the origin of the decrease in Gf.
