Research On Properties Of Polyphenylene Oxide/ Polyamide 66/Carbon Black/Sisal Fiber Electromagnetic Shielding Composites

Today, the research on polymer- matrix electromagnetic shielding composites is becoming a major focus, because of the low density, high corrosion resistance, ease of processing of the polymer. This paper introduced a kind of electromagnetic shielding composite which was prepared by using polyphenylene oxide(PPO) and polyamide 66(PA66) as matrix, and conductive carbon blacks(CB) and steam explosed sisal fibers(SF) as fillers. The effect of d ifferent component formulas on electromagnetic shielding and mechanical properties of PPO/PA66 alloy, PPO/PA66/C B composite and PPO/PA66/C B/SF composite was researched. Then, a set of optimization formulas were determined. The theoretical shielding effectiveness(SE) calculated by Schelkunoff formula was compared with the experimental SE. Finally, Scanning electron microscope was used to observe the microstructures of the composites.The research showed that PPO/PA66 alloy with the addition of 5phr SEBS-g-MAH and 5 phr SEBS could maintain excellent tensile strength and flexural strength, and the notched impact strength of the al oy was improving.For PPO/PA66/CB composite, when the the mass ratio of PPO/PA66 was 1/3 and the CB content was 20 wt%, the electromagnetic shielding and mechanical properties were the most excellent comprehensively. In this proportion, the SE was up to 25.7d B at 900 MHz in low frequency range and 27.6d B at 17 GHz in high frequency range. At the same time, the percolation phenomenon occurred when the CB content was 15wt%.For PPO/PA66/CB/SF composite, when the the mass ratio of PPO/PA66 was 1/3, C B/SF was 1/1 and the CB content was 20 wt%, the electromagnetic shielding and mechanical properties of the composite were the most excellent comprehensively. In this proportion, the SE was up to 43 d B at 900 MHz in low frequency range and 43.5d B at 17 GHz in high frequency range. The percolation threshold of the C B content was 15wt%. These SE could meet the civil standard. Finally, this research also found that Schelkunoff formula could predict the SE of these two kinds of composites reliably.