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Fabrication and Characterization of Low-Cost Raw Coconut Husk and Activated Carbon Coconut Husk/Epoxy-3D Printed Honeycomb Structure as An Electromagnetic Wave
Absorbing Material
Raudhahtul Insyirah Miswan
1, Muadzam Fahmy Mokhtar
1and Fadzidah Mohd Idris
11Kolej GENIUS Insan, Universiti Sains Islam Malaysia, Bandar Baru Nilai, Nilai, Malaysia Email: [email protected]
Abstract. In this modern era full of technological advancement, it requires an urgent need for lightweight, thin, and flexible electromagnetic-interference (EMI) absorbing materials to overcome the increasingly serious radiation pollution around us. Thus, this research is conducted to introduce new the electromagnetic wave absorption properties by varying the materials’ content being incorporated into epoxy matrix at different thicknesses. The materials introduced as filler is synthesize by using coconut husk powder and activated carbon from coconut husk. This prepared agricultural waste powder/epoxy are further incorporated into 3Dprinted honeycomb structure of thickness 1 and 2 mm. The samples’ electromagnetic wave characterization and micro structural properties are characterized by using Vector Network Analyzer (VNA) in a wide frequency range from 4 GHz to 18 GHz and Field Emission Electron Microscopy (FESEM) respectively. The prepared agriculture polymer composites are expected to be very useful in many applications especially military application such as radar cross section reduction and for prevention of electromagnetic interference in electrical devices. Moreover, the performance of a device can be maximized by eliminating any unwanted interference, besides preventing any health problems related to radiation.
Keyword: Coconut husk, electromagnetic wave, absorbing material, honeycomb structure, 3D printed
Introduction
Recently, researchers are focusing on identifying the most low-cost, and suitable carbon material from agricultural waste to be incorporated in the structure of electromagnetic wave absorbing material. This is due to the known fact about carbon element in agricultural waste such as coconut husk that can absorb unwanted electromagnetic wave signal. During recent years, humans are contending in developing new devices that can be utilized to fulfill human needs, provides various facilities especially from hazard at higher and wider frequency range (gigahertz).
Typically, electrical devices radiate electromagnetic interference (EMI) that carries negative feedback on device performances and also the encompassing environment. It is likely for them to cause malfunctions of electronic devices and become a serious threat to the health of living things. These complications triggers research interest in fabricating electromagnetic wave absorbing materials that have high electromagnetic wave absorbing properties, flexible, affordable, thin and featherweight. These can maximize the amount of EMI being absorbed thus reduced the hazard of the EMI towards humans‘ health.
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Material and methods
Filler material preparation
The raw coconut husk and activated carbon coconut husk were collected commercially to decrease the amount of agricultural waste. After that, the raw coconut husk is first dried in an oven at 60 degree overnight to vaporize any water content. The dried coconut husk was taken to crush it into powder form by using a crusher for 12 minutes while the activated carbon coconut husk was commercially collected in powder form.
Figure 1. 40 ml activated
carbon coconut husk Figure 2. Powder
activated coconut husk Figure 3. 40 ml of raw
coconut husk Figure 4. Raw coconut husk in powder form
Matrix preparation
The matrix was fabricated by mixing the epoxy resin and hardener that were collected commercially at optimized ratio of (4 ml :1 ml). The mixture was stirred gently by using a glass rod for 5 minutes.
Composite preparation
The filler material was mix with matrix and the composites were prepared in weight ratio 1:9 (80 % for raw material, 20 % of epoxy resin). Then, the mixture was poured into a 3D-printed honeycomb structure with a measurement of 5x5cm. Sample 1 was prepared using raw coconut husk as the filler material while Sample 2 was prepared using activated carbon coconut husk as the filler material.
Composite characterization
The composite sample prepared were characterized by using Vector Network Analyzer (VNA) and Field Emission Scanning Electron Microscope (FESEM).
Results and discussions
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Figure 5. Sample 1 Figure 6. Sample 2
The samples fabricated were flexible and lightweight. They were also 1 mm and 2 mm thin. The sample is expected to enhance electromagnetic wave absorption properties as a result of the multiple reflections and porous structure which due to the outcomes of morphology and honeycomb 3D printed structures. The data collected from this research can be used as a reference and guidance for the development of new and improved electromagnetic absorbing materials in the near future.
Conclusions
Raw Coconut Husk and Activated Carbon Coconut Husk/Epoxy 3D printed Honeycomb Structure has been successfully fabricated. These composite sample is expected to produce excellent electromagnetic wave absorbing performance and further to be used as an electromagnetic wave absorbing material in many applications.
Acknowledgment
The authors acknowledge Ministry of Higher Education and Universiti Sains Islam Malaysia for financial support under Fundamental Research Grant Scheme (FRGS/1/2020/STG05/USIM/02/3) and USIM-RACER Grant (PPPI/USIM-RACER_0120/KGI/051000/11920). The authors also express deepest gratitude and pleasure towards Kolej GENIUS Insan for providing the apparatus and equipment used in laboratory.
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