Natural fiber-metallic composites with remarkable gradient structures

Abstract

A novel natural fiber-metallic composite (NMC) with remarkable gradient structure is presented in this paper. Natural fibers generated from poplar wood, preformed into mat, are pre-treated through an in-situ impregnation process with Fe2+ and Fe3+ solutions. After the incorporation of ammonia, the iron oxide particles are formed inside the porous structures of fiber mat. The treated natural fiber mat with a certain moisture content, is then densified into composites through a compression molding process under a certain temperature, that a high-strength NMC is created without using binders. The resulted composites exhibited high iron oxide loading of 34.9 %, and presented a remarkable gradient structure with porous scale-like metallic surface and well-distributed uniform-sized nanoparticles for the core. The NMC also demonstrated a high flexural strength of 92.5 MPa, which was 2.2 times higher than that of poplar wood (42.6 MPa), and showed a strong magnetic response of 11.1 emu g−1 in saturation magnetization. The gradient structures of NMC can be controlled through changing the fiber mat density, impregnation process, mat moisture content, and compression molding parameters.