Furfural-Based Diepoxy as a Reactive Diluent for Bisphenol A Diglycidyl Ether

A low-viscosity furfural-based diepoxy was synthesized and evaluated as a reactive diluent for diglycidyl ether of bisphenol A (DGEBA) to reduce viscosity. The diluent was blended with DGEBA at different ratios and compared with a commercial reactive diluent, 1,6-hexanediol diglycidyl ether (HDDGE). Both diluents notably reduced the viscosity of DGEBA. Anhydride-cured epoxy networks containing the biobased diepoxy showed only a slight decrease in glass transition temperature, whereas HDDGE caused a stronger reduction. Thermal stability of the cured systems remained largely unchanged. Tensile strength was significantly improved with the incorporation of either diluent, with the biobased diepoxy-modified systems showing the highest values. Although HDDGE exhibited better compatibility with DGEBA in adhesion studies, the neat biobased diepoxy showed 50% higher adhesive strength compared to DGEBA. These results indicate that the synthesized diepoxy can be applied as an efficient biobased reactive diluent for epoxy resins and possibly as an adhesive in high-performance applications.