Microwave and Reflection Properties of Palm Shell Carbon–Polyester Conductive Composite Absorber

Abstract

Sifat gelombang mikro seperti kebertelusan ε dan tangen kehilangan tan δ bagi suatu komposit bersifat pengalir menggunakan campuran karbon kelapa sawit dengan resin poliyester tak tepu dikaji pada julat frekuensi 8 GHz hingga 12 GHz. Pengukuran pada ε and tan δ menekankan kepada pengaruh kandungan karbon (jisim %) menggunakan kelapa sawit yang dipirolisis pada 600°C, 700°C and 800°C. Peningkatan kandungan karbon di dalam setiap komposit dilihat mempengaruhi peningkatan ε and tan δ. Ujian kebolehpantulan gelombang mikro turut dilakukan dengan menggunakan 30% karbon kelapa sawit di dalam panel komposit poliyester bersaiz 450 mm × 450 mm. Keputusan menunjukkan ketebalan komposit telah mempengaruhi kehilangan pantulan pada frequensi gelombang mikro yang sama. Kehilangan pantulan sehingga –20 dB dapat dikesan pada julat frekuensi tertentu. Ini menunjukkan kemungkinan penggunaan karbon daripada sisa kelapa sawit dalam menghasilkan kehilangan yang berkesan kepada penyerapan gelombang mikro, selain menjadi alternatif dalam menghadapi peningkatan sisa kelapa sawit di dalam negara. Kata kunci: Komposit bersifat pengalir, penyerap gelombang mikro, karbon, penggunaan sisa The microwave properties of permittivity, ε and loss tangent, tan δ of conductive composite utilizing palm shell carbon mixed with unsaturated polyester resin were studied in the 8 to 12 GHz frequency range. The measurement of ε and tan δ emphasize on the influence of carbon concentration (mass %) of palm shell pyrolysed at 600, 700 and 800°C. It was observed that the increase of carbon concentration inside each measured composite influenced the increase of ε and tan δ condition. A microwave reflectivity test was also conducted by using 30% palm shell carbon in a 450 × 450 mm polyester composite panel. The result indicated that the composite thickness had influenced the reflection loss curve throughout the same microwave frequencies. The reflection loss up to –20 dB was possible in specific effective frequency ranges. This indicated the possibility of using carbon derived from palm shell residue in providing significant loss that contributed to microwave absorption, as well as an alternative in managing the increased of oil palm shell residues throughout the country. Key words: Conductive composite, microwave absorber, carbon, waste utilization