Papers by Ibrahim Abubakar Alhaji
Recycled soda lime silica glass inclusion in polytetrafluoroethylene matrix as reinforcement for microwave substrate application
Materialwissenschaft und Werkstofftechnik
Recycled soda lime silica glass‐filled polytetrafluoroethylene composites were prepared for subst... more Recycled soda lime silica glass‐filled polytetrafluoroethylene composites were prepared for substrate application at microwave frequencies. Various volume fractions (0.05–0.25) of the filler were dispersed in the polytetrafluoroethylene matrix. The composites’ dielectric, mechanical, and thermal properties were examined with respect to the filler content. X‐ray diffraction data established the phase structure of the polytetrafluoroethylene matrix and recycled soda lime silica glass. Scanning electron microscope micrographs revealed uniform filler distribution at lower recycled soda lime silica contents, while energy dispersive x‐ray analysis showed the purity of the composites. The tensile strength of the composites reduced from 13.5 MPa to 4.26 MPa, while the moisture absorption and density raised from 0.07 % and 2.195 g/cm3 to 0.19 % and 2.228 g/cm3 when the recycled soda lime silica filler volume fraction was adjusted from 0.05–0.25. The lowest coefficient of thermal expansion va...
The Effect of grain size on the complex permittivity of Oil Palm Empty Fruit Bunch Fiber for Microwave Application
SLU Journal of Science and Technology, Dec 7, 2020
Oil palm empty fruit bunch (OPEFB) fiber, a waste product from oil palm mill is 100% biodegradabl... more Oil palm empty fruit bunch (OPEFB) fiber, a waste product from oil palm mill is 100% biodegradable, environmentally friendly, and cheap was prepared and characterized for possible microwave absorbing material by determining its permittivity for fiber size and frequency. The dielectric properties were investigated by the use of open-ended coaxial (OEC) probe at microwave frequency 8-12 GHz range. The results showed that the dielectric properties of the OPEFB fiber material can be influenced by changing its particle size (100, 200, 300, 400, and 500 µm). The dielectric constant (and loss factor (increased as the particle size of the fiber decreased. The values for the lowest and highest fiber size (100 and 500 µm) were found to be 3.13 and 2.81 while values were 0.38 and 0.26 respectively. Improved complex permittivity with reduced particle size demonstrated their suitability for making composites that could attenuate microwaves within the X-band frequency range.
Polymers, 2021
The purpose of this study was to improve the dielectric, magnetic, and thermal properties of poly... more The purpose of this study was to improve the dielectric, magnetic, and thermal properties of polytetrafluoroethylene (PTFE) composites using recycled Fe2O3 (rFe2O3) nanofiller. Hematite (Fe2O3) was recycled from mill scale waste and the particle size was reduced to 11.3 nm after 6 h of high-energy ball milling. Different compositions (5–25 wt %) of rFe2O3 nanoparticles were incorporated as a filler in the PTFE matrix through a hydraulic pressing and sintering method in order to fabricate rFe2O3–PTFE nanocomposites. The microstructure properties of rFe2O3 nanoparticles and the nanocomposites were characterized through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM). The thermal expansion coefficients (CTEs) of the PTFE matrix and nanocomposites were determined using a dilatometer apparatus. The complex permittivity and permeability were measured using rectangular waveguide connected to vector n...
Polymers, 2021
Low dielectric loss and low-cost recycled borosilicate (BRS) glass-reinforced polytetrafluoroethy... more Low dielectric loss and low-cost recycled borosilicate (BRS) glass-reinforced polytetrafluoroethylene (PTFE) composites were fabricated for microwave substrate applications. The composites were prepared through a dry powder processing technique by dispersing different micron sizes (25 µm, 45 µm, 63 µm, 90 µm, and 106 µm) of the recycled BRS filler in the PTFE matrix. The effect of the filler sizes on the composites’ thermal, mechanical, and dielectric properties was studied. The dielectric properties of the composites were characterised in the frequency range of 1–12 GHz using an open-ended coaxial probe (OCP) connected to a vector network analyser (VNA). XRD patterns confirmed the phase formation of PTFE and recycled BRS glass. The scanning electron microscope also showed good filler dispersion at larger filler particle sizes. In addition, the composites’ coefficient of thermal expansion and tensile strength decreased from 12.93 MPa and 64.86 ppm/°C to 7.12 MPa and 55.77 ppm/°C whe...
International Journal of Digital Information and Wireless Communications, 2015
This work investigates performance anomaly of IEEE 802.11 multi-rate WLAN with respect to through... more This work investigates performance anomaly of IEEE 802.11 multi-rate WLAN with respect to throughput and fairness. Even though in a given WLAN, hosts with different transmission rates exist, IEEE 802.11 allows them to only transmit equal-sized frames. This is unfair and reduces the overall throughput of the network. A new technique is proposed in this work to mitigate this problem by making the transmission time of the host equal instead, thereby adjusting their packet sizes in proportion to their individual transmission rates. Analytical and simulation analyses show that the proposed scheme eliminates the anomaly by improving the throughput and fairness index (FI) of a given WLAN.
Materials
This study was aimed at fabricating composites of polylactic acid (PLA) matrix-reinforced oil pal... more This study was aimed at fabricating composites of polylactic acid (PLA) matrix-reinforced oil palm empty fruit bunch (OPEFB) fiber filled with chemically reduced graphene oxide (rGO). A total of 2–8 wt.% rGO/OPEFB/PLA composites were characterized for their complex permittivity using an open-ended coaxial probe (OEC) technique. The shielding efficiency properties were calculated using the measured transmission (S21) and the reflection (S11) coefficient results. All the measurements and calculations were performed in the 8–12 GHz frequency range. The morphological and microstructural study included X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and Fourier transform infrared spectroscopy (FTIR). The results indicated that the incorporation of rGO as filler into the composites enhanced their complex permittivity properties. The composites showed a total shielding efficiency (SET) of about 31.2 dB at a frequency range of 8–12 GHz, which suggests their us...
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Papers by Ibrahim Abubakar Alhaji