Dual-functional natural-fiber reinforced composites by incorporating magnetite.

Natural fiber reinforced composites with dual-functional properties, including electromagnetic shielding and paramagnetic functions, as well as improved water-resistant property, were fabricated using vacuum assisted resin transfer molding (VARTM) process. Magnetite particles were firstly mixed with kenaf fibers to form a mat, followed by resin intrusion and compression for the composite fabrication. The obtained kenaf fiber/magnetite/polyester composites were endowed with electromagnetic shielding and paramagnetic properties, without compromising the mechanical properties. When 35.2% magnetite was incorporated into the composites, the electromagnetic interference shielding effectiveness reached 79.2% with the range 8–12 GHz, and the saturation magnetization was 29.2 emu g −1 . The 24-h thickness swelling and water absorption of the composites after introducing magnetite were drastically reduced from 19.7% to 2.4% and 18.3% to 2.6%, counting as the decreases of 87.6% and 73.4%, respectively. It was indicated that the water resistance of the composite was improved significantly. [ABSTRACT FROM AUTHOR]