Orientated CNT‐polypropylene nanocomposite films made from extruded monofilaments

Abstract

In this study, a method for making an orientated polymer nanocomposite film was developed. Melt‐drawn nanocomposite monofilaments of isotactic polypropylene and acicular nanofillers, i.e. carbon nanotubes (CNT) or vapor grown carbon nanofibers (VGCF), were prepared and characterized from the aspect of polymer chain orientation, mechanical properties, and overall morphology. A marked improvement in mechanical properties was observed as a function of the addition of CNT, increasing draw down ratio (DDR) and annealing. Nanocomposite films were prepared from drawn monofilaments by hot‐pressing under low pressure in order to maintain the orientation of the monofilaments. Wide angle X‐ray diffraction showed a high degree of residual orientation in the films. Electron microscopy (high‐resolution scanning electron microscopy, transmission electron microscopy) unexpectedly revealed that the CNT‐matrix interface is amorphous. However, differential scanning calorimetry found no measurable influence of the CNT on the overall crystallinity as determined by the enthalpy of melting of the matrix. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers

Unidirectional spread‐tow carbon fiber/polypropylene composites reinforced with mechanically aligned multi‐walled carbon nanotubes and exfoliated graphite nanoplatelets

“…Carbon nanomaterials (CNMs) have been used in various applications such as energy harvesting [7], structural health monitoring [8], and polymer composites [9][10][11] owing to their extremely high mechanical properties, electrical properties, surface area, and aspect ratio. In addition, they can be aligned in polymer composite films by the tensile load at the slit-die of the extruder during the extrusion process [1,12,13]. Moreover, CNMs can act as nucleating sites for the growth of orientated crystalline structures to enhance crystallization kinetics [13][14][15][16][17][18][19].…”

“…Hence, the importance of unidirectional multiscale hybrid composites (MHCs) has been increasing in academic and industrial research owing to their outstanding mechanical properties that strongly depend on the alignment orientation of the fibers. In addition, properties of nanocomposite films, which are a matrix of MHC reinforced with graphene oxide, carbon nanotube (CNT), exfoliated graphite nanoplatelet (xGnP), and so forth, are affected by the orientation of the polymer molecules and nanomaterials . Polypropylene (PP) is one of the most common thermoplastics because it provides superior qualities, and it is the most versatile among thermoplastics.…”

Crystalline structure and thermodynamic analysis of ultra‐low diameter VGCF‐polypropylene nanocomposite monofilaments

“…The crystalline structure of nanocomposites as studied here is determined by a number of factors, including the interaction between the nanoparticles and the matrix (e.g., nucleation), the processing conditions (e.g., flow), and dimensional boundaries (e.g., confinement and size restrictions). Adding nanofillers not only reinforces the matrix , acts as a nucleating agent due to its large surface area , and facilitates orientation , but may also increase confinement. Molecules within a semicrystalline polymer matrix can be confined by imposing geometrical constraints during crystallization from the melt.…”