Poly(lactic acid)/carbon nanotube composites with enhanced electrical conductivity via a two-step dispersion strategy

Abstract

Conductive polymer composites (CPCs) prepared by melt blending techniques display promising shielding properties, and could help address the growing challenges posed by electromagnetic interferences. However, it remains challenging with current processing techniques to achieve high electrical conductivity in CPCs owing to the poor dispersion of conductive fillers in polymer matrix. Herein, we propose a “two-step dispersion strategy” to enhance the electrical conductivity of poly (lactic acid) (PLA)/carbon nanotubes (CNTs) composites by employing Pickering emulsion templating and masterbatch blending method. The CNTs were dispersed uniformly via regenerated cellulose-assisted assembly on the surface of Pickering emulsions to yield PLA/CNT masterbatch. This was followed by melt blending with PLA granules to form an interconnected CNTs network within the PLA matrix. The resulting PLA/CNT composite exhibited a low percolation threshold of 0.46 vol%, and a high electrical conductivity of 72.2 S/m at 5.6 wt% CNT loading. Materials produced using this method outperformed PLA/CNT composites obtained by direct melt blending. Furthermore, the composite exhibited a maximum EMI shielding effectiveness of 31.1 dB, and superior tensile strength of 71.4 MPa. The “two-step dispersion strategy” provides an effective and versatile route to solve the dispersion problem of CNT and fabricate high performance CPCs.