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search.filters.applied.f.access: openAccess × End date: 2019 × Start date: 2017 × Type: Article × Type: Text × Version: submittedVersion ×

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    An updated micromechanical model based on morphological characterization of carbon nanotube nanocomposites
    (Oxford [u.a.] : Elsevier, 2017) Talò, Michela; Krause, Beate; Pionteck, Jürgen; Lanzara, Giulia; Lacarbonara, Walter
    By leveraging on extensive morphological analysis of carbon nanotube nanocomposites, an update of the Eshelby-Mori-Tanaka method is proposed for a more accurate estimation of the nanocomposites effective elastic response. The experimental results are employed to overcome the main modeling limitations inherent in most common micromechanical theories, such as the perfect dispersion of the nanofiller and the uniformity of the nanofiller's aspect ratio within the nanocomposite. The actual variability of the CNTs aspect ratio and the CNTs degree of dispersion are experimentally measured and introduced in the proposed model by averaging the Eshelby tensor over the actual CNT lengths distribution and by accounting for the effective CNT volume fraction. The effects of the nanofiller morphology on the mechanical response of three different thermoplastic nanocomposites with low- and high-aspect ratio CNTs are explored, and monotonic tensile tests are performed to validate the predictions of the proposed model. A good agreement is found between the predicted nanocomposites elastic moduli and the experimental data.
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    Extruded polycarbonate/Di-Allyl phthalate composites with ternary conductive filler system for bipolar plates of polymer electrolyte membrane fuel cells
    (Bristol : IOP Publ., 2019) Naji, Ahmed; Krause, Beate; Pötschke, Petra; Ameli, Amir
    Here, we report multifunctional polycarbonate (PC)-based conductive polymer composites (CPCs) with outstanding performance manufactured by a simple extrusion process and intended for use in bipolar plate (BPP) applications in polymer electrolyte membrane (PEM) fuel cells. CPCs were developed using a ternary conductive filler system containing carbon nanotube (CNT), carbon fiber (CF), and graphite (G) and by introducing di-allyl phthalate (DAP) as a plasticizer to PC matrix. The samples were fabricated using twin-screw extrusion followed by compression molding and the microstructure, electrical conductivity, thermal conductivity, and mechanical properties were investigated. The results showed a good dispersion of the fillers with some degree of interconnection between dissimilar fillers. The addition of DAP enhanced the electrical conductivity and tensile strength of the CPCs. Due to its plasticizing effect, DAP reduced the processing temperature by 75 °C and facilitated the extrusion of CPCs with filler loads as high as 63 wt% (3 wt% CNT, 30 wt% CF, 30 wt% G). Consequently, CPCs with the through-plane electrical, in-plane electrical and thermal conductivities and tensile strength of 4.2 S cm-1, 34.3 S cm-1, 2.9 W m-1 K-1, and 75.4 MPa, respectively, were achieved. This combination of properties indicates the potential of PC-based composites enriched with hybrid fillers and plasticizers as an alternative material for BPP application.