Broadband microwave absorbing materials for green electronics based on poly (lactic acid)/ethylene‐vinyl acetate copolymer blends loaded with carbon nanotube

Abstract

AbstractPartially bio‐based conducting polymer nanocomposites constituted by poly(lactic acid) (PLA)/ethylene‐co‐vinyl acetate (EVA) (50:50 wt%) blend loaded with different amounts of carbon nanotube (CNT) were prepared for developing microwave absorbing materials. The effect of EVA characteristics and the mixing conditions on the electrical conductivity was investigated. The higher conductivity value was achieved using PLA@CNT master batch and EVA with 28% of VA. In fact, this system presented electrical percolation threshold of 7 × 10−4 volume fraction and a conductivity value of 3 × 10−3 S/m with the addition of 0.9 wt% (0.58 vol%) of CNT. A minimum reflection loss of −29 dB (electromagnetic (EM) attenuation of around 99.9%) at 11.7 GHz and the bandwidth (<−10 dB) of 4.9 GHz was observed with the presence of 0.58 vol% of CNT, whereas RL value of around −39.4 dB (EM attenuation of around 99.99%) at 14.7 GHz and a bandwidth of 4.6 GHz was observed for the composite loaded with 0.25 vol% of CNT. Due to the outstanding microwave absorption properties and wide absorption bandwidth with low amount of CNT, these composites are promising candidates for flexible materials suitable for shielding electronic devices in a wide frequency range.