The Synergistic Toughening and Strengthening Effects of Cork Particles and Nanocellulose on Rosin-Based Epoxy Resin

In order to develop a bio-based epoxy resin with high mechanical and thermal performance, cork particles and nanocellulose were introduced into the rosin-based epoxy resin to improve the toughness, stiffness and thermal stability. The flexural properties of the epoxy composites indicated that the strength and modulus were reduced when the content of cork particles was relatively high (>3%) due to the low stiffness and modulus of cork itself. However, the flexural performance was significantly improved after the addition of 1% nanocellulose. In contrast to the flexural properties, the impact toughness results showed the synergistic toughening effects of nanocellulose and cork particles on the rosin-based epoxy resin. The highest impact toughness of 13.35 KJ/m(2) was found in the epoxy composite with 1% cellulose nanofibers and 3% cork particles, an increase of 149.07% compared to the neat epoxy. Cork particle size also had a significant effect on the mechanical properties of the composites. Both the flexural and impact results showed first a rise and then a fall with a decrease in the cork size. TGA results indicated cork particles and nanocellulose could have a synergistic enhancing effect on the thermal stability of the rosin-based epoxy resin. This work can add value to rosin and cork waste and widen the industrial applications of the epoxy resin.