Fabrication of Conductive Microfilaments and Liquid Sensor from CNTs/PLA Nanocomposites

Abstract

Electrically conductive composites (ECCs) have recently shown a very high potential to replace metals for several applications such as electromagnetic interference (EMI) shielding, sensors, antistatic coatings, and flexible electrodes. The ECCs are mainly composed of a conductive filler dispersed in a polymer matrix. In this work we demonstrate the fabrication of a nanocomposite by dispersing carbon nanotubes (CNTs) in polylactic acid (PLA) by using the ball mill mixing method. Nanocomposites with various concentrations of CNTs in PLA were fabricated and their electrical conductivities were measured. The ball mill mixing method enabled us to make CNT/PLA with a very high concentration of CNTs (up to 40 wt.%). The PLA/CNTs were extruded from a micronozzle to fabricate nanocomposite filaments with a diameter as small as ~ 70 μm and a high electrical conductivity reaching up to ~4000 S/m. Conductive porous structures (CPSs) were fabricated by hot pressing the conductive filaments. The application of these CPSs is shown here as a liquid sensor since their electrical resistivity changes when they get in contact with acetone. These CPSs are promising candidates for liquid sensor and EMI shielding applications due to their lightweight, mechanical flexibility and electrical conductivity.