Effect of toughening agents on the properties of poplar wood flour/poly (lactic acid) composites fabricated with Fused Deposition Modeling

This study was aimed at improving the toughness and interfacial properties of poplar wood flour/polylactic acid (PLA) composites by Fused Deposition Modeling. The effect of toughening agents was discussed. The results showed that, the addition of thermoplastic polyurethane (TPU) significantly increased the impact strength of composites by 51.31%.Comparing to other toughening agents, such as polycaprolactone (PCL) and poly (ethylene-co-octene) (POE), the compatibility between wood flour and PLA was superior when TPU was used. With the addition of TPU, the complex viscosity and the storage modulus of the composites were highly increased. The graft copolymers (GC), synthesized by free-radical melt grafting using glycidyl methacrylate as a graft monomer and dicumyl peroxide as an initiator, were used as compatibilizers in the composites. With the addition of 5 wt% wood flour loading, the grafting degree of GC was enhanced by 61.54%. At a 2 wt% loading of the GC, the impact strength and tensile strength of composites increased by 7.75% and 8.39%, respectively, and the interfacial adhesion of the ternary composites were improved.