High absorption shielding material of poly(phthalazinone etherketone)/multiwall carbon nanotube composite films with sandwich configurations.

Sandwich structure can be induced to achieve excellent electromagnetic interference shielding effectiveness (EMI SE) as is well known. However, how to optimize the structure to achieve performance optimization is still a problem. Herein, a poly(phthalazinone etherketone)/multiwall carbon nanotube (PPEK/MWCNT) composite with homodisperse and high content (15 wt%) of MWCNT was prepared by a water induced phase separation process. A sandwich structure was designed by introducing a wave-transmitting layer between the PPEK/MWCNT composite films. The MWCNT loading of the shielding layer and the wave-transmitting layer thickness () were varied to systematically investigate their influence on shielding performance in the X-band (8.2-12.4 GHz). EMI SE shows strong value dependence. When the shielding layer was fixed, EMI SE showed a trend of decreasing, rising, leveling off and then decreasing again with value increasing. The value in the leveling off stage is the best value for performance optimization. The best value decreased with increasing MWCNT content of the shielding layer. An absorption dominated SE up to 65 dB and a high increment rate of 140% of SE were achieved by optimization of the value and shielding layer.