Does the Type of Polymer and Carbon Nanotube Structure Control the Electromagnetic Shielding in Melt-Mixed Polymer Nanocomposites?

The Effect of Multi-Walled Carbon Nanotubes on the Material Properties of Polyamide 66 Nanocomposites

The aim of this study was to evaluate the effect of multi-walled carbon nanotubes (CNTs) on various material properties of the polyamide 66 (PA66) nanocomposites. This is achieved first by investigating the effect of CNTs (0.1-5 wt.%) on the material properties of PA66 pellets, and second, on the injection-molded PA66/CNT nanocomposites. Thermal analysis revealed that CNTs do not have a significant effect on the melting behavior and melting temperature of PA66/CNT nanocomposites, but they increase the crystallization temperature of the nanocomposites. Rheological analysis showed that the melt shear viscosity of the PA66 increased with increasing CNT content particularly above 1 wt.%. Additionally, the PA66 nanocomposites exhibit shear-thinning behavior, and this effect is more significant at higher CNT contents. The FT-IR analysis revealed the absence of chemical bonds between PA66 and CNTs and, consequently, the uniform dispersion of CNTs in the PA66 matrix. Mechanical testing indicated that the inclusion of CNTs (0.1 to 5 wt.%) in PA66 matrix could not improve the tensile modulus to a great extent, while it decreased the ultimate tensile strength of PA66 nanocomposites under tension. On the other hand, CNTs positively influenced the mechanical behavior under bending (+15% increase at 5 wt.%). Among the nanocomposites, PA66 filled with 5 wt.% CNTs exhibited the optimal mechanical performance in terms of tensile strength (58 MPa), tensile modulus (2689 MPa), bending modulus (2072 MPa), and bending strength (104 MPa). The experimental results also showcase the significant improvement in the tensile and bending mechanical properties of the injection-molded PA66 nanocomposites after thermal annealing at -40 °C and 180 °C for one hour. This experimental study provides guidelines for the structure-property-processability of the PA66 nanocomposites, revealing the complex relationship between the CNTs and the enhancement of mechanical properties, while highlighting the potential of thermal annealing in improving the mechanical performance of PA66 nanocomposites. This will be further investigated to promote the use of PA66 nanocomposite in industrial applications.

Carbon Nanotube/Polymer Composites for Functional Applications

Carbon nanotubes (CNTs) have garnered significant interest in the field of nanotechnology owing to their unique structure and exceptional properties. These materials find applications across a diverse array of fields, including electronics, environmental science, energy, and biotechnology. CNTs serve as potent reinforcing agents in polymer composites; even minimal additions can significantly improve the mechanical, electrical, and thermal properties of polymers. With the growing demand for polymer composites across various industries, there is an anticipation for CNT/polymer composites to evolve in increasingly diverse directions. This paper reviews recent advancements in the manufacturing techniques of various CNT/polymer composites and discusses the enhancements in their mechanical, electrical, and thermal properties. Furthermore, it explores the potential applications of these composites.

Thermoelectric Performance of Polypropylene/Carbon Nanotube/Ionic Liquid Composites and Its Dependence on Electron Beam Irradiation

The thermoelectric behavior of polypropylene (PP) based nanocomposites containing single walled carbon nanotubes (SWCNTs) and five kinds of ionic liquids (Ils) dependent on composite composition and electron beam irradiation (EB) was studied. Therefore, several samples were melt-mixed in a micro compounder, while five Ils with sufficiently different anions and/or cations were incorporated into the PP/SWCNT composites followed by an EB treatment for selected composites. Extensive investigations were carried out considering the electrical, thermal, mechanical, rheological, morphological and, most significantly, thermoelectric properties. It was found that it is possible to prepare n-type melt-mixed polymer composites from p-type commercial SWCNTs with relatively high Seebeck coefficients when adding four of the selected Ils. The highest Seebeck coefficients achieved in this study were +49.3 µV/K (PP/2 wt.% SWCNT) for p-type composites and −27.6 µV/K (PP/2 wt.% SWCNT/4 wt.% IL type AMIM Cl) for n-type composites. Generally, the type of IL is decisive whether p- or n-type thermoelectric behavior is achieved. After IL addition higher volume conductivity could be reached. Electron beam treatment of PP/SWCNT leads to increased values of the Seebeck coefficient, whereas the EB treated sample with IL (AMIM Cl) shows a less negative Seebeck coefficient value.