Synergistic toughening of epoxy resin by block ionomers and carbon nanofibers

Epoxy has been widely used in practical applications because of its excellent properties such as high tensile strength, high stiffness, strong chemical stability and excellent thermal performance, however, the brittleness has limited its further potentials. In this work, ternary polymer composites have been prepared by incorporating acidified carbon nanofibers (CNFs) and sulfonated polystyrene-block-poly (ethylene-co-butylene)-block-polystyrene (SSEBS) into epoxy resin using solution processing method. The synergistic strengthening and toughening effects of the hybrid fillers have been explored using quasi-static mechanical tests and microscopic morphology characterization. The mechanical properties of the ternary composites have been optimized by varying the loading amount of SSEBS and CNFs. The results show that when the loading amounts of SSEBS and CNFs are 10 wt% and 0.75 wt%, respectively, the composites deliver the highest fracture toughness of 1.39 KJ/m², which has been enhanced by a factor of 500 % as compared with pure epoxy while the tensile strength has been increased slightly without sacrificing its strength.