Complex permittivity and power loss characteristics of α-Fe2O3/polycaprolactone (PCL) nanocomposites: effect of recycled α-Fe2O3 nanofiller

Abstract

The development of microwave absorbing materials based on recycled hematite (α-Fe 2 O 3 ) nanoparticles and polycaprolactone (PCL) was the main focus of this study. α-Fe 2 O 3 was recycled from mill scale and reduced to nanoparticles through high energy ball milling in order to improve its complex permittivity properties. Different compositions (5% wt., 10% wt., 15% wt. and 20% wt.) of the recycled α-Fe 2 O 3 nanoparticles were melt-blended with PCL using a twin screw extruder to fabricate recycled α-Fe 2 O 3 /PCL nanocomposites. The samples were characterized for their microstructural properties through X - ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The complex permittivity and microwave absorption properties were respectively measured using the open ended coaxial (OEC) probe and a microstrip in connection with a vector network analyzer in the 1–4 GHz frequency range. An average α-Fe 2 O 3 nanoparticle size of 16.2 nm was obtained with a maximum imaginary (ε " ) part of permittivity value of 0.54 at 4 GHz. The complex permittivity and power loss values of the nanocomposites increased with recycled α-Fe 2 O 3 nanofiller content. At 2.4 GHz, the power loss (dB) values obtained for all the nanocomposites were between 13.3 dB and 14.4 dB and at 3.4 GHz, a maximum value of 16.37 dB was achieved for the 20 % wt. nanocomposite. The recycled α-Fe 2 O 3 /PCL nanocomposites have the potential for use in noise reduction applications in the 1–4 GHz range.

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

“…The materials used for these processing techniques were an electromagnet which produced 1 Tesla magnetic field intensity, a thin cylindrical glass tube open at both ends and deionized water of density 1 g/cm 3 . The CTST was used to separate the wustite (FeO) and magnetite (Fe 3 O 4 ) contained in the mill scale slurry collected in the cold water separation process [23]. In this separation step, the clamped glass tube closed at the bottom end with a glass stopper, was filled with hot deionized water (100 • C) followed by a small quantity of the slurry.…”

“…The interface polarization increased due to the differences in polarization of the rFe 2 O 3 nanofiller and PTFE matrix. The increment in complex permittivity with increasing rFe 2 O 3 nanofiller can be attributed to the polarization process due to the enhanced conductivity and interfacial polarization in the composite and hopping exchange of charges between localized states [23]. One more reason for the influence on the relative complex permittivity of the nanocomposites is the particle size of rFe 2 O 3 nanofiller since the nano size had high specific surface area that enabled good contact between the particles and the matrix [47].…”

“…However, the ε of the PTFE sample did not change with frequency because PTFE is a nonpolar polymer [50], which means its complex permittivity is not dependent on frequency. The increment in complex permittivity with increasing rFe2O3 nanofiller can be attributed to the polarization process due to the enhanced conductivity and interfacial polarization in the composite and hopping exchange of charges between localized states [23]. One more reason for the influence on the relative complex permittivity of the nanocomposites is the particle size of rFe2O3 nanofiller since the nano size had high specific surface…”

“…The rFe 2 O 3 nanofiller with enhanced relative complex permittivity can be embedded with a non-conducting polymer matrix such as PTFE to prepare a novel absorber which could have promising attenuation properties for electromagnetic interference (EMI) suppression. This absorber can be further enhanced by the magnetic nature of the Fe 2 O 3 nanoparticles and with their high interfacial density due to their good compactness [ 23 ].…”

Recycled soda lime silica glass inclusion in polytetrafluoroethylene matrix as reinforcement for microwave substrate application

“…The peak intensity of pure polytetrafluoroethylene at 2θ = 18.05° related to the polytetrafluoroethylene crystalline phase reduced noticeably, while the other smaller peaks protruded. In addition, the absence of undesirable peaks or shifts indicates that the interaction between recycled soda lime silica filler and polytetrafluoroethylene matrix is purely physical, not chemical [48].…”