Structure and properties of wet-spun nylon/graphene nanocomposite fibers

Due to an increasing demand for more portable and intelligent electronic devices, strong and flexible fibers which are also electrically conductive and thermally stable are currently on demand. Herein, wet-spun nylon/graphene nanoplatelets (GNPs) and nylon/reduced graphene oxide (rGO) nanocomposite fibers were fabricated in a range of filler loadings and the effect of the type of graphene employed and the presence/absence of ions absorbed into the fibers during coagulation on their structure, processing and properties was evaluated. The diameters were homogenous along the fibers and similar for identical loadings of both fillers. The increasing viscosities of the dopes with increasing filler loadings were, however, reducing progressively the processability of the systems, leading to increasingly thicker and more defective fibers. The nanocomposite fibers behaved as electrically percolated systems, with considerably lower percolation threshold found for the rGO based fibers relative to the GNPs based ones due to the higher aspect ratio of rGO relative to GNPs. The richer surface chemistry of the rGO flakes provided stronger filler–polymer interfaces, leading to a higher optimal loading and effective modulus relative to the GNPs system. Whereas the presence of ions from the coagulation bath did not affect the diameters, microstructure or electrical properties of the fibers, it was found to have an impact on their mechanical properties, thermal stability and melting and crystallization behavior. This knowledge is key to gain control on the design of nanostructured fibers with specific structure and properties that meet the requirements for particular applications in the field of multifunctional textiles.