Correlation of mechanical and electrical properties with processing variables in MWCNT reinforced thermoplastic nanocomposites

Abstract

The influence of the processing variables and nanotube content on the mechanical and electrical properties of Polyamide 6,6-based nanocomposites reinforced with Multi-Walled Carbon Nanotubes (MWCNTs) is investigated. Results show that variation in the processing variables such as compounding method, injection melt temperature, injection speed, mold temperature, and holding pressure varies the properties significantly. In fact, composites containing similar contents of the nanofillers show variations in mechanical properties up to 30.0 % and in the electrical properties up to three orders of magnitude. Different processing parameters required for achieving optimal mechanical and electrical performances were also found. Correlation between processing parameters and microstructure within the nanocomposites was also studied. Results show that variation of the processing parameters defines the existence or absence of a nanotube network in the nanocomposite structure. Experimental and micromechanical modeling results show that less control over the nanocomposite morphology and nanotube alignment is achievable in higher nanofiller contents. The underlying mechanisms responsible for the modulation in the properties are also discussed using scanning and transmission electron microscopy, rheological and crystallization investigations. The research provides a recipe to manufacture the tailored nanocomposite with the specified properties for various industrial applications.

Investigation of conductive hybrid polymer composites reinforced with copper micro fibers and carbon nanotubes produced by injection molding

“…However, while their aspect ratios provide larger interfacial regions leading to enhancement of the properties, their processing is challenging. In fact, achieving dispersed or aligned nanofillers requires effective prior investigations [8,9,25]. Results showed that incorporation of 4 vol.…”

“…Recent advancements in technology demand for novel electrically and/or thermally conductive multifunctional plastics with the potential to be fabricated precisely, and through mass manufacturing processes. Incorporation of various conductive fillers such as metals fibers, carbon black, carbon fibers, and low melting alloys in the polymers to create a conductive network within a polymeric base has been one of the attempts toward this target [6][7][8][9][10].…”

“…While reducing the average distance between the fillers is desirable to achieve higher conductivities, increasing the content of these conventional conductive fillers within the polymeric system aftercertain volume contents leads to poor processibility, and degradation of other properties especially mechanical behaviors [8,12]. In fact, metallic fillers are traditionally considered as the prime candidates to achieve high levels of conductivity in plastics, however, their susceptibility to oxidation, corrosion, and high densities and costs are some of their major drawbacks.…”

“…Inclusion of conductive nanofillers in addition to enhancement of the primary desired conductivity properties could additionally increase other properties such as stiffness, hardness, damping, etc. [8]. However, inclusion of nanofillers within polymers does not result into electrical properties as high as their metallic filler competitors such as Copper, Silver, and Aluminum [8,16].…”

“…[8]. However, inclusion of nanofillers within polymers does not result into electrical properties as high as their metallic filler competitors such as Copper, Silver, and Aluminum [8,16]. Therefore, in order to evade from the negative impacts resulting from high filler contents, a combination of different conductive fillers with different geometries, properties, and contents should be investigated.…”