Preparation and Properties of Wood Flour Reinforced Lignin-Epoxy Resin Composite

A lignin-epoxy resin composite was prepared by blending lignin/wood flour with an epoxy resin and polyamine. The effects of the wood flour on the mechanical, thermal creep, and creep recovery properties, as well as the microstructure of the composite, were studied. Among the mechanical properties, the initial modulus increased with increasing content of wood flour. The glass transition temperature (T-g) decreased, and the thermal stability first decreased and then increased, as the wood flour content increased. As the wood flour's particle size was decreased, the initial modulus and other mechanical properties first increased and then decreased slightly. The Tg increased, and the thermal stability first decreased and then increased. The creep resistances of the composite were improved after the addition of the wood flour, and the 40 to 60 mesh wood flour exhibited better improvement than 60 to 120 mesh. The scanning electron microscopy (SEM) analysis revealed good interfacial bonding between the lignin, epoxy resin, and wood flour. Fiber breakage and fiber pullout were the main failure modes observed in this study.