In situ polymerization of functionalized multiwalled-carbon nanotubes/epoxy resin composite fibers using a non-solvent technique

The aim of this study was to produce carbon nanotubes (CNTs)/polymer composite fibers by wet spinning without any solvent. The functionalized multiwalled-carbon nanotubes (F-MWNTs)/epoxy resin was synthesized by in situ polymerization method. Epoxy resin, F-MWNTs, and curing agent were mixed and injected by a syringe pump. The effects of operating parameters including the percentage of CNTs and the extrusion velocity of the syringe pump on the dispersion and alignment of F-MWNTs in the cross-section of F-MWNTs/polymer composite fibers were investigated. The composite fibers were characterized by tensile strength analysis, scanning electron microscopy (SEM), and electrical conductivity analysis. The experimental results showed that a decrease (30 ml/h to 15 ml/h) in extrusion velocity increased the electrical conductivity of composite fibers by more than 3%. This behavior was attributed to the higher alignment of F-MWNTs and improved conducting pathways along the composite fiber axis, as observed by SEM. In addition, by reducing extrusion velocity (30 ml/h to 15 ml/h), the tensile strength of composite fibers was enhanced just over twofold due to the better arrangement of CNTs which can be attributed to the further retention time of composite fibers and the pressure of the walled-needle. Moreover, the higher the processing time of spinning, the lower electrical conductivity of the fibers is which might be due to the higher coagulation of fibers.