Synthesized Hybrid CNT Polymer Composite in Reducing EMI Pollution at Gigahertz Frequency Range

Abstract

Modern digital systems are seriously impacted by the electromagnetic (EM) danger caused by various EM wave that interfere one another, either internally or externally. The electromagnetic interference (EMI) pollution has become an attention among researchers since it not only affects the devices, but also affecting human and biological systems. Thus, synthesizing an EM wave absorber that able to absorb the unwanted EM wave signal is crucial.  This research highlight on the materials’ properties and characterization of the synthesized nanometer size hybrid Carbon Nanotubes (CNTs) of individual ferrite (Ni_0.5Zn_0.5Fe₂O₄ or Carbonyl iron) and mixed ferrite (Ni_0.5Zn_0.5Fe₂O₄ + Carbonyl iron) as catalyst to grow CNTs by using Chemical Vapour Deposition (CVD) method. The synthesized hybrid CNTs used as fillers were mixed with epoxy resin and hardener as the matrix at certain ratio of thickness fixed at 1 mm, 2 mm, and 3 mm. The hybrid CNTs was analysed by using X-ray diffractometer (XRD), a Field emission Scanning Electron Microscope (FeSEM) and RAMAN spectrometer to determine the phase formation, microstructural and structural analysis respectively. On the other hand, the Vector Network Analyzer (VNA) measured at 8 to 18 GHz frequency range was used to measure and analyse the microwave characterization. The phase analysis confirmed the existence of Carbon and Iron Carbide, whereas the microstructural shows the synthesized hybrid CNTs are mostly straight like, twisted and spiral fiber. Moreover, the structural analysis shows more defective structure with the formation of multiwalled CNTs that helps in absorbing the EM wave. The reflection loss (RL) of the growth individual Ni_0.5Zn_0.5Fe₂O₄ and Carbonyl Iron shows the RL value of -18 dB and -15 dB of thickness 2 mm respectively. The RL result also show improvement in the RL values for the growth of mixed ferrite with RL reach until -26 dB (thickness=3mm). Consequently, it indicates that using both single and mixed ferrite as a catalyst to grow CNT produces better EM wave performance appropriate for various applications.