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DDC: 620 × Subject: Nanocomposite ×

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    Polyethylene glycol-modified poly(styrene-co-ethylene/butylene-co-styrene)/carbon nanotubes composite for humidity sensing
    (Lausanne : Frontiers Media, 2019) Mičušík, Matej; Chatzimanolis, Christos; Tabačiarová, Jana; Kollár, Jozef; Kyritsis, Apostolos; Pissis, Polycarpos; Pionteck, Jürgen; Vegso, Karol; Siffalovic, Peter; Majkova, Eva; Omastová, Mária
    Polymeric composites of the linear triblock copolymer poly(styrene-co-ethylene/butylene-co-styrene) grafted with maleic anhydride units (SEBS-MA) or MA modified by hydrophilic polyethylene glycol (PEG) and containing various amounts of multiwall carbon nanotubes (MWCNTs) as conducting filler—were prepared by solvent casting. The MWCNT surface was modified by a non-covalent approach with a pyrene-based surfactant to achieve a homogeneous dispersion of the conducting filler within the polymeric matrix. The dispersion of the unmodified and surfactant-modified MWCNTs within the elastomeric SEBS-MA and SEBS-MA-PEG matrices was characterized by studying the morphology by TEM and SAXS. Dynamical mechanical analysis was used to evaluate the interaction between the MWCNTs and copolymer matrix. The electrical conductivity of the prepared composites was measured by dielectric relaxation spectroscopy, and the percolation threshold was calculated. The prepared elastomeric composites were characterized and studied as humidity sensor. Our results demonstrated that at MWCNTs concentration slightly above the percolation threshold could result in large signal changes. In our system, good results were obtained for MWCNT loading of 2 wt% and an ~0.1 mm thin composite film. The thickness of the tested elastomeric composites and the source current appear to be very important factors that influence the sensing performance. © 2019 Mičušík, Chatzimanolis, Tabačiarová, Kollár, Kyritsis, Pissis, Pionteck, Vegso, Siffalovic, Majkova and Omastová.
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    Fabrication of metastable crystalline nanocomposites by flash annealing of Cu47.5Zr47.5Al5 metallic glass using joule heating
    (Basel : MDPI AG, 2020) Okulov, I.; Soldatov, I.; Kaban, I.; Sarac, B.; Spieckermann, F.; Eckert, J.
    Flash Joule-heating was applied to the Cu47.5Zr47.5Al5 metallic glass for designing fully crystalline metastable nanocomposites consisting of the metastable B2 CuZr and low-temperature equilibrium Cu10Zr7 phases. The onset of crystallization was in situ controlled by monitoring resistivity changes in the samples. The effect of heating rate and annealing time on the volume fraction of the crystalline phases and mechanical properties of the nanocomposites was studied in detail. Particularly, an increase of the heating rate and a decrease of the annealing time lead to a lower number of equilibrium Cu10Zr7 precipitates and an increase of tensile ductility. Tailoring of these non-equilibrium microstructures and mechanical properties may not be possible unless one starts with a fully glassy material that opens new perspectives for designing metastable nanomaterials with unique physical properties.