Electromagnetic shielding properties of iron oxide impregnated kenaf bast fiberboard

Abstract

The electromagnetic shielding effectiveness of kenaf bast fiber based composites with different iron oxide impregnation levels was investigated. The kenaf fibers were retted to remove the lignin and extractives from the pores in fibers, and then magnetized. Using the unsaturated polyester and the magnetized fibers, kenaf fiber based composites were manufactured by compression molding process. The transmission energies of the composites were characterized when the composite samples were exposed under the irradiation of electromagnetic (EM) wave with a changing frequency from 9 GHz to 11 GHz. Using the scanning electron microscope (SEM), the iron oxide nanoparticles were observed on the surfaces and inside the micropore structures of single fibers. The SEM images revealed that the composite's EM shielding effectiveness was increased due to the adhesion of the iron oxide crystals to the kenaf fiber surfaces. As the Fe content increased from 0% to 6.8%, 15.9% and 18.0%, the total surface free energy of kenaf fibers with magnetizing treat increased from 44.77 mJ/m 2 to 46.07 mJ/m 2 , 48.78 mJ/m 2 and 53.02 mJ/m 2 , respectively, while the modulus of elasticity (MOE) reduced from 2,875 MPa to 2,729 MPa, 2,487MPa and 2,007 MPa, respectively. Meanwhile, the shielding effectiveness was increased from 30-50% to 60-70%, 65-75% and 70-80%, respectively.

Dual-functional natural-fiber reinforced composites by incorporating magnetite

“…In summary, the addition of magnetite could help improving the anti-flexural properties. In a report [29] of magnetite loaded kenaf fiber reinforced composites fabricated using the traditional hot-pressing method, MOE was decreased from 2,875 MPa to 2,729 -2,007 MPa after introducing magnetite particles. However, in this work the MOE was significantly increased.…”

“…These drawbacks deter it from the practical applications in the EMI shielding field. To avoid the problems mentioned above, the EMI shielding composites based on the lignocellulosic fibers are considered as the potential candidates [26][27][28][29][30], which are light, corrosion resistant, easily manufactured, economical, and environmentally friendly. Recently, the graphene nanoribbon [31], nano-carbon [22], magnetron sputtering [32] and powdered activated carbon [33] were used to enhance the EMI shielding.…”

“…The magnetite was used to fabricate composites because of the electromagnetic absorbing and paramagnetic properties [29,40,41]. The most magnetite was formed in situ from ferric ion and base solution [29,42], which might cause chemical pollution and not be convenient for the industrial production.…”

“…The most magnetite was formed in situ from ferric ion and base solution [29,42], which might cause chemical pollution and not be convenient for the industrial production. However, the pollution can be avoided by directly using the magnetite particles.…”

Fabrication of Wood Fiber-rubber Composites with Reclaimed Rubber

“…By taking advantage of both materials, WRCs could have multi-functional properties and excellent potential for extended applications. A number of previous studies have been conducted on the manufacturing of WRCs using wood, adhesives, and waste rubber powder with hotpressing technology (Xu et al 2014;Ding et al 2015;Xia et al 2015). Waste rubber powder is used as a filler and the adhesive is used as a bonding agent.…”