Influence of MWCNT transfer on the properties of MWCNT/PLA/PE blends

The influence of carbon nanotubes (CNTs) transfer and mixing time on the microstructure, processing behavior, electrical resistivity, and electromagnetic interference (EMI) shielding characteristics of 80/20 vol/vol polylactic acid (PLA)/high-density polyethylene (HDPE) blend filled with 5 wt% (3.7 vol%) CNTs were investigated. For CNTs-filled PLA/HDPE blends, it is known that CNTs selectively localize in the HDPE domain. Thus, in this work, CNTs were initially premixed with the PLA, and then the HDPE was added to monitor the nanotubes transfer and investigate the effects of nanotubes transfer from the PLA phase to the HDPE phase on the composite properties. The analysis of scanning electron microscope graphs showed that most of the nanotubes transferred from the PLA phase to the HDPE phase in less than 1.0 min without any accumulation of the nanotubes at the PLA/HDPE interface. The CNTs/PLA/HDPE composite exhibited an increase in electrical resistivity and a decrease in EMI shielding with the increase in CNTs transfer time. For example, the EMI shielding decreased from 22.7 dB to 16.8 dB by increasing the transfer time from 1 min to 2 min. Thus, preparing the blends at the shortest possible mixing time is recommended to obtain the highest possible EMI performance.