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Author: Krause, Beate × End date: 2019 × Start date: 2010 × Type: article × WGL Institute: IPF ×

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    Impact of synthesis temperature on morphology, rheology and electromagnetic interference shielding of CVD-grown carbon nanotube/polyvinylidene fluoride nanocomposites
    (Lausanne : Elsevier Sequoia, 2017) Mirkhani, Seyyed Alireza; Arjmand, Mohammad; Sadeghi, Soheil; Krause, Beate; Pötschke, Petra; Sundararaj, Uttandaraman
    Employing chemical vapor deposition technique, multi-walled carbon nanotubes (CNTs) were synthesized over Fe catalyst at a broad range of temperatures, i.e. 550° C to 950° C (at 100° C intervals). CNTs were melt-mixed into a polyvinylidene fluoride (PVDF) matrix at various loadings, and then compression molded. Surprisingly, despite the ascending trend of CNT powder conductivity with the synthesis temperature, the nanocomposites made with CNT synthesized at 650° C had significantly lower percolation threshold (around 0.4 wt%) and higher electromagnetic interference shielding effectiveness (EMI SE) (20.3 dB over the X-band for 3.5 wt% CNT and 1.1 mm thickness) than the other temperatures. Exhaustive characterization studies were conducted on both CNTs and composites to unveil their morphological and electrical characteristics. Superior EMI shielding of CNT650° C was attributed to a combination of high carbon purity, aspect ratio, crystallinity, and moderate powder conductivity along with decent state of dispersion within the PVDF matrix.
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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.