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Author: Pötschke, Petra × End date: 2023 × Start date: 2023 × Start date: 2009 × Version: publishedVersion × Subject: Seebeck coefficient × WGL Institute: IPF ×

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    Thermoelectric Properties of N-Type Poly (Ether Ether Ketone)/Carbon Nanofiber Melt-Processed Composites
    (Basel : MDPI, 2022) Paleo, Antonio Jose; Krause, Beate; Soares, Delfim; Melle-Franco, Manuel; Muñoz, Enrique; Pötschke, Petra; Rocha, Ana Maria
    The thermoelectric properties, at temperatures from 30 °C to 100 °C, of melt-processed poly(ether ether ketone) (PEEK) composites prepared with 10 wt.% of carbon nanofibers (CNFs) are discussed in this work. At 30 °C, the PEEK/CNF composites show an electrical conductivity (σ) of ~27 S m−1 and a Seebeck coefficient (S) of −3.4 μV K−1, which means that their majority charge carriers are electrons. The origin of this negative Seebeck is deduced because of the impurities present in the as-received CNFs, which may cause sharply varying and localized states at approximately 0.086 eV above the Fermi energy level (EF) of CNFs. Moreover, the lower S, in absolute value, found in PEEK/CNF composites, when compared with the S of as-received CNFs (−5.3 μV K−1), is attributed to a slight electron withdrawing from the external layers of CNFs by the PEEK matrix. At temperatures from 30 °C to 100 °C, the σ (T) of PEEK/CNF composites, in contrast to the σ (T) of as-received CNFs, shows a negative temperature effect, understood through the 3D variable-range hopping (VRH) model, as a thermally activated hopping mechanism across a random network of potential wells. Moreover, their nonlinear S (T) follows the same behavior reported before for polypropylene composites melt-processed with similar CNFs at the same interval of temperatures.
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    Messanlage zur Untersuchung des Seebeck-Effektes in Polymermaterialien
    (Berlin : De Gruyter, 2020) Jenschke, Wolfgang; Ullrich, Mathias; Krause, Beate; Pötschke, Petra
    The thermoelectric effect named after the physicist Thomas Johann Seebeck has been investigated sufficiently well for all technically relevant metals and has been used for a long time, among other things, for temperature measurement by means of thermocouples. Less well known and researched is the Seebeck effect in polymer materials, which are gaining increasing influence in the sensor industry today. This article describes a measuring system designed specifically to study the Seebeck effect in polymeric samples with the aim of developing tailored polymers for sensory engineering applications using the Seebeck effect. The special requirement of the measuring system is the realization of constant accurate temperature sources.