Complex Permittivity and Microwave Absorption Properties of OPEFB Fiber–Polycaprolactone Composites Filled with Recycled Hematite (α-Fe2O3) Nanoparticles

Abstract

Recycled hematite (α-Fe2O3) nanoparticles with enhanced complex permittivity properties have been incorporated as a filler in a polycaprolactone (PCL) matrix reinforced with oil palm empty fruit bunch (OPEFB) fiber for microwave absorption applications. The complex permittivity values were improved by reducing the particle sizes to the nano scale via high-energy ball milling for 12 h. A total of 5–20 wt.% recycled α-Fe2O3/OPEFB/PCL nanocomposites were examined for their complex permittivity and microwave absorption properties via the open ended coaxial (OEC) technique and the transmission/reflection line measurement using a microstrip connected to a two-port vector network analyzer. The microstructural analysis of the samples included X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR). At 1 GHz, the real (ε′) and imaginary (ε″) parts of complex permittivity of recycled α-Fe2O3 particles, respectively, increased from 7.88 to 12.75 and 0.14 to 0.40 when the particle size was reduced from 1.73 μm to 16.2 nm. A minimum reflection loss of −24.2 dB was achieved by the 20 wt.% nanocomposite at 2.4 GHz. Recycled α-Fe2O3 nanoparticles are effective fillers for microwave absorbing polymer-based composites in 1–4 GHz range applications.

Effects of Recycled Fe2O3 Nanofiller on the Structural, Thermal, Mechanical, Dielectric, and Magnetic Properties of PTFE Matrix

“…The study of synthetic techniques for ferrite nanoparticles production has recently attracted considerable attention in view of their excellent magnetic and electrical properties [ 2 ]. Up to date, various techniques have been used for the synthesis of Fe 2 O 3 nanoparticles (Reference code: 00-024-0072) such as electrospinning technique [ 3 ], reduction-oxidation process [ 4 ], and hydrolysis process [ 5 ].…”

“…The electro-Fenton system was synthesized by combining multiwall carbon nanotubes and Fe@Fe 2 O 3 nanowires with PTFE [ 19 ]. It is also worth noting that Fe 2 O 3 nanoparticles have been widely used as fillers to enhance the dielectric and magnetic properties of various matrixes such as polycaprolactone (PCL) [ 2 ], polyaniline (PANI) [ 20 ], silica [ 21 ], and poly(methyl methacrylate) (PMMA) [ 22 ]. However, rFe 2 O 3 nanoparticles have never been used as fillers in PTFE matrix for microwave absorption applications yet.…”

The Effect of MWCNTs Filler on the Absorbing Properties of OPEFB/PLA Composites Using Microstrip Line at Microwave Frequency

“…The effect of the 6–22 wt.% MWCNTs filler on the dielectric properties of OPEFB/PLA/MWCNTs composites was studied, and the variation in and values in the range of 8–12 GHz is shown in Figure 7 . It has been reported that the quality of conductive fillers distributed in a polymer matrix will play a significant role in the entire sample’s dielectric behaviors [ 26 ]. PLA polymer has low permittivity because of the small amount of macromolecular polarization.…”

Complex Permittivity and Electromagnetic Interference Shielding Effectiveness of OPEFB Fiber-Polylactic Acid Filled with Reduced Graphene Oxide

“…The measurements for the complex permittivity of the composites were carried out using the OEC probe HP85071C technique (Agilent, Santa Clara, CA, USA). The probe was connected to an HP8720B Vector Network Analyzer (VNA) via a high-precision coaxial test cable [ 24 ]. The OEC probe is particularly suited for the measurements of complex permittivity of liquid.…”