Orientation of Well-Dispersed Multiwalled Carbon Nanotubes in Melt-Spun Polymer Fibers and Its Impact on the Formation of the Semicrystalline Polymer Structure: A Combined Wide-Angle X-ray Scattering and Electron Tomography Study

Abstract

The orientation behavior of well-dispersed multiwalled carbon nanotubes (CNTs) within high-speed melt-spun semicrystalline polymer fibers has for the first time been studied using three-dimensional reconstructions from bright-field transmission electron microscopy (TEM) tomography. The local investigation technique allows separating contributions stemming from additionally present CNT aggregates. Over a relatively narrow draw ratio range applied during the fiber production process, a transition region is found, in which the CNTs change their orientation from being aligned perpendicular to being aligned parallel to the fiber axis. Complementary performed wide-angle X-ray scattering measurements and mechanical analysis of the polymer/CNT nanocomposite fibers reveal a strong correlation between the CNT orientation and the structural and mechanical properties of the fibers. Characteristic quantities such as crystallinity, crystal size, and correlation length parameters of crystalline and amorphous polymer chains undergo significant changes within the CNT orientation transition region indicative of a cooperative process.

A review of the interfacial characteristics of polymer nanocomposites containing carbon nanotubes

“…73,74 While the spatial resolution achieved with transmission electron microscopy can offer sufficient information about the microstructure of carbon nanotubes, there are intrinsic challenges and imaging artifacts that need special attention to properly characterize the bulk characteristics of polymer nanocomposite materials. 75,76…”

Structure evolution in poly(ethylene terephthalate) (PET) – Multi-walled carbon nanotube (MWCNT) composite films during in-situ uniaxial deformation

“…Following the structure evolution in polymer-CNT composites during processing is not straightforward and requires techniques that allow timeresolved data acquisition ranging from less than a second to several minutes depending on the processing conditions. The isothermal crystallization of PET-CNT composites is often monitored using thermal, infrared and X-ray techniques which probe the crystallization kinetics, crystallinity, orientation/chain conformation and confinement of the host polymer [13][14][15][18][19][20][21][22][23][24].…”

“…Vad [21] detailed the structure evolution and mechanical properties of high speed melt-spun PET-MWCNT fibres. It was argued that there is a critical draw ratio (DR) for the fibres which induce CNT orientation parallel to the draw direction.…”

Novel Carbon Nanotube/Cellulose Composite Fibers As Multifunctional Materials

“…30,31 Detailed descriptions are annexed in the Supporting Information and elsewhere. 32,33 2.4. Characterization of the Sensing Abilities.…”