Novel mechanism for spinning continuous twisted composite nanofiber yarns

Highly aligned and twisted composite Nylon 6 nanofibers incorporating multiwall carbon nanotubes (MWCNTs) were successfully electrospun, using a novel mechanism. It has been found that; ultrasound combined with high speed shearing is the simplest and most convenient method to improve the dispersion of MWCNTs into a polymer matrix with a certain loading. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were conducted to characterize the morphology of nanofibers, the dispersion of MWCNTs and their alignment inside the fiber body. By manipulating the electrical forces during electrospinning and applying mechanical stretching to the electrospun nanofibers, high polymer chain orientation and better alignment of the MWCNTs particles along the fiber axis was achieved. Twist was applied to the nanofibers for providing the required inter fiber lateral cohesion interaction and friction thus, spinning a continuous twisted composite yarn. SEM images show twisted yarns with diameters ranging between 5 and 10 µm. The twist effect of the parallel bundle was investigated by controlling the twist per unit length using a motor speed controller at values of 100, 250, 500, 750 and 1000 rpm. The paper also provides a comprehensive review of various yarn spinning mechanisms of electrospun nanofibers. © 2007 Elsevier Ltd. All rights reserved.