Preparation of MWCNTs grafted with polyvinyl alcohol through Friedel–Crafts alkylation and their composite fibers with enhanced mechanical properties

An effective method to increase the mechanical properties of poly (vinyl alcohol) (PVA) and multi-walled carbon nanotubes (MWCNTs) composite fibers is reported. MWCNTs in the composite fibers were functionalized with PVA through a one-step grafting process by the nondestructive Friedel–Crafts alkylation in an aluminum chloride medium. Under suitable conditions, the resulting functionalized MWCNTs (f-MWCNTs) of the selected content of 0.05 wt% based on the PVA weight were added to a DMSO/H₂O (vol ratio = 3/1) mixed solvent, and the f-MWCNTs were highly dispersed in the solution, which remained uniform even after 30 days. The solution was gel spun and the as-spun fibers were hot-drawn to prepare the final PVA/f-MWCNTs composite fibers. The tensile strength and modulus of the fibers were found to be about 926 MPa and 59 GPa, which increased by 280.6% and 421.0% relative to pure PVA fibers, respectively.