Investigation of crystalline and tensile properties of carbon nanotube-filled polyamide-12 fibers melt-spun by industry-related processes

Abstract

This paper addresses the influence of carbon nanotubes (CNT) on the structure and mechanical properties of high tensile strength thermoplastic polymer fibers. Polyamide (PA) fibers with different draw ratios, with and without CNTs as fillers, and having mechanical properties close to industrial standards were spun in a pilot melt spinning plant. The morphology of the fibers was investigated using optical microscopy, nuclear magnetic resonance (NMR) and 2-D wide angle x-ray diffraction (WAXD). Differential scanning calorimetry (DSC) was carried out to get an estimate of the crystallinity. For a concise interpretation of the results of the tensile measurements performed on the fibers, a parameter was developed to account for the detrimental influence of polymer extrusion on their mechanical properties. The CNTs seemed to act as sites for the growth of un-oriented crystalline domains converted from oriented regions, without yielding a mechanical reinforcing effect.