Distinct strategy for the improvement of conductivity and electromagnetic shielding properties of MWCNTs/PLA/PBS composites: Synergistic effects of double percolation structure and UV aging

Abstract To reveal a relationship among crystallization, conductivity and electromagnetic shielding properties of full biodegradable polymer after ultraviolet (UV) aging, polybutylene succinate (PBS)‐based composites with different weight ratios of multi‐wall carbon nanotubes (MWCNTs)/polylactic acid (PLA) /PBS masterbatch were processed via melt‐compounding approach. Morphology of the MWCNTs/PLA/PBS masterbatch prepared by Pickering emulsion method was confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM) observation. Comprehensive effects of different content of masterbatch and UV aging time on the morphology, crystallization, and electrical and electromagnetic shielding properties of MWCNTs/PLA/PBS composites were shown by Fourier transform infrared spectroscopy (FTIR), SEM, wide angle X‐ray diffraction (WAXD), differential scanning calorimeter (DSC), polarizing microscope (POM), ultra‐depth of field optical microscope, resistance tester, and vector network analyzer. Compared with PBS composite with 0.1 wt% MWCNTs, the electrical conductivity of PBS composite with the MWCNTs/PLA/PBS masterbatch increased by two orders of magnitude, and dispersed morphology for the composite showed double percolation structure. After UV aging, both MWCNTs/PBS composites and the PBS composites with the MWCNTs/PLA/PBS masterbatch, their surface presented burnt yellow and parts of flaws, while both their electrical conductivity and total electromagnetic shielding effectiveness gradually increased. Moreover, with the increasing of UV aging time, not only crystal size of these PBS‐based composites became large, but also their crystal interface became clearer. Furthermore, when UV aging time reached 528 h, the tensile strength of 0.6 M/PLA/PBS composite decreased by 12.6%, while its total electromagnetic shielding effectiveness increased by 39.8%, compared with the composite without UV aging.