Toughening of dicyandiamide-cured DGEBA-based epoxy resin using MBS core-shell rubber particles

A diglycidyl ether bisphenol-A-based epoxy resin, cured using a dicyandiamide hardener, has been toughened by the addition of core-shell rubber particles, methyl methacrylate-butadiene styrene. Different amounts of core-shell particles (2.5, 3.75, and 5 wt%) were added to the epoxy resin and their effect on the fracture, mechanical-physical, and thermal properties of the epoxy resin was investigated. The fracture surfaces of the samples were studied using a scanning electron microscope. The results showed that increasing methyl methacrylate-butadiene-styrene particles in epoxy resin increased the fracture toughness (K IC ) and fracture energy (G IC ) of the modified epoxy resin compared with the unmodified epoxy resin. The tensile strength and Young’s modulus of the modified epoxy resin decreased slightly and the glass transition temperature, cure onset, peak and end temperatures remained approximately constant. Scanning electron microscope revealed that the unmodified epoxy resin fracture surface was smooth and brittle, but the modified epoxy resin showed significant plastic deformation.