Conductive Graphene-Polyethylene Terephthalate Composite Yarns with Synergistic Multiwalled Carbon Nanotube Additives by Melt-Spinning

Conductive graphene yarns are pivotal for embedding electronic and intelligent capabilities into fabrics. The study presents successful fabrication of conductive graphene-polyethylene terephthalate (PET) composite yarns with synergistic multiwalled carbon nanotube (MWCNT) additives through the melt-spinning process, a widely used industrial method for polymer yarn manufacturing. The integration of MWCNTs significantly improves yarns' electrical conductivity, achieving nearly a 100-fold increase compared to MWCNT-PET composite yarns. The electrical performance of these yarns is primarily determined by interfacial contacts between conducting nanomaterials, which can be conceptualized as quantum tunneling barriers with multiple molecular energy levels at their extremities. Employing the Simmons model, the current-voltage characteristics is analyzed through a segmented fitting approach to extract critical barrier parameters. The equivalent barrier height and width remain constant across variations in applied voltage, nanomaterial concentration, and temperature. However, the effective total contact area increases significantly with higher nanomaterial contents, thereby substantially boosting the yarns' electrical conductivity. The larger graphene size (approximate to 200 nm) in comparison with the MWCNT diameter (approximate to 5 nm) results in a substantially greater interfacial area at graphene-MWCNT contacts compared to MWCNT-MWCNT contacts. This disparity in contact area is the primary factor contributing to synergistic enhancement of electrical conductivity in graphene-PET composite yarns.