Ultra‐high‐molecular‐weight polyethylene (UHMWPE) nanocomposite fibers were fabricated using solution spinning, consisting of surface modified single‐walled carbon nanotubes (SWCNTs) embedded into the fiber matrix. The SWCNTs were modified using polyvinylpyrrolidone (PVP) noncovalent functionalization process, which acts as a surfactant and has the ability to enhance the dispersion of CNTs in the base polymer matrix by reducing aggregation and promoting interfacial adhesion with the fiber polymer matrix. Tensile testing of fibers containing PVP‐coated SWCNTs showed substantial improvements in the tensile strength and fracture strain by 125% and 137%, respectively, compared to fibers containing pristine CNTs. The amount of PVP coated onto the surfaces of CNTs was determined to be about 32.5% using thermogravimetric analysis (TGA). Differential scanning calorimetry (DSC) analysis of the nanocomposite fibers showed significant increase in crystallinity and upshift in the melting point compared to that of neat UHMWPE fibers. Fourier transform infrared spectroscopy (FTIR) analysis showed the presence of characteristic absorbance bands of PVP functional groups (CN @ 1289 cm−1 and CO @ 1651 cm−1) on the modified CNTs. Scanning electron microscopy (SEM) imaging of modified CNTs and nanocomposite fibers showed an increase in average tube diameter and reduced aggregate formation compared to pristine CNTs, indicating the successful coating of the nanotubes with PVP. Preferential alignment of the modified CNTs along the direction of fiber extrusion and crack bridging of the fiber by nanotubes were also observed. POLYM. COMPOS., 39:E1025–E1033, 2018. © 2017 Society of Plastics Engineers

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We report the fabrication of Cellulose Acetate (CA) based fibers reinforced with Multi-Walled Carbon Nanotubes (MWCNTs) using a solution spinning process. The motivation of this work is to produce high performance fibers based on sustainable natural materials as an alternative to synthetic fibers for structural applications. A 30 wt% solution of CA in a binary solvent system of N, N-dimethylacetamide (DMAc) and Acetone (3:7 v/v) was used for the solution spinning of CA fibers. Both neat and CNT-loaded CA fibers were produced. The CNT loading with respect to the polymer was at 0.5 wt%. For CA-MWCNT spinning solutions, the MWCNTs were initially dispersed in the solvent and then CA is added and mixed together. The mixing temperature kept 40–45°C. The viscosity of the CA solution was 8,000 cP. Addition of MWCNT increased the viscosity of the CA solution to 32,000 cP. A lab-scale solution spinning line consisting of a constant torque high temperature gear pump and heated extrusion channels was used to produce both neat and CA-MWCNT fibers. The solution was pumped through a spinneret at the end of the extrusion channel with an orifice as a viscous gel-like filament which was passed through a spool placed in a coagulation bath and then it formed as fiber. The fibers are collected to a takeup roll at a draw ratio of 8.0. Characterization studies of both neat and MWCNT loaded fibers were performed differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA) and scanning electron microscopy (SEM). DSC analysis of fibers showed reduction in crystallinity of CA upon inclusion of 0.5 wt% MWCNT. TGA analysis showed improvement of thermal stability in CA-MWCNT fibers compared to neat CA. Cross-sections of neat CA fibers showed smooth surfaces with no significant defects, while CA-MWCNT showed formation of micro-voids and irregular features. Longitudinal views of outer surface of both neat CA and CA-MWCNT fibers showed no indication of surface defects or protrusions.