Ultralow percolation threshold biodegradable PLA/PBS/MWCNTs with segregated conductive networks for high‐performance electromagnetic interference shielding applications

Abstract The formation of dense and complete conductive networks in the electromagnetic interference (EMI) shielding composite is the basis for its excellent EMI shielding performance. In this work, biodegradable poly (lactic acid)/poly (butylene succinate)/multi‐walled carbon nanotubes (PLA/PBS/MWCNTs) nanocomposites with segregated structures were successfully prepared via melt blending. Due to the successful preparation of segregated structures and the fact that MWCNTs were mainly dispersed in the PBS phase, an ultralow percolation value of 0.071 vol% was achieved in biodegradable PLA/PBS/MWCNTs nanocomposites. When the MWCNTs content is 0.499 vol%, the electrical conductivity of the PLA/PBS/MWCNTs nanocomposites with segregated structures is around 7.15 × 10 −3 S/m, which is about 6 orders of magnitude higher than that of the PLA/PBS/MWCNTs nanocomposites with normal structures. When the MWCNTs content increased to 2.0 wt%, the average EMI shielding effectiveness (SE) of segregated structures remained stable at 27.56 dB, which can effectively block 99.82% of the microwave radiation. Furthermore, as suggested in the EMI shielding analysis, the EMI shielding of PLA/PBS/MWCNTs nanocomposites is mainly through absorption shielding, so there will be no secondary environmental pollution. This study provides a practical and universal method to prepare biodegradable conductive polymer composites with ultralow percolation threshold and excellent EMI SE.