In the context of the current urgent energy problems, one approach to improve the energy efficiency of equipment or systems is waste heat recovery. Waste heat is a by-product of many production processes and, if not reused, is released into the atmosphere or water. By using the Seebeck or thermoelectric (TE) effect, a net zero emission of energy transfer from heat to electrical energy can be achieved if suitable electrically conductive materials are used.
Compared to the traditionally used TE devices, which often contain rare earth metals, polymer-based TE materials have only recently been developed and investigated. While rare earth metals are sometimes toxic, expensive, involve geopolitical risks in extraction and are difficult to process, polymers are not only much cheaper and more environmentally friendly, they also allow for easy and inexpensive processing in flexible shapes and have inherently low thermal conductivity. In addition to intrinsically conductive polymers (ICPs), electrically conductive polymer composites (CPCs) are a suitable alternative, especially when produced by melt processing [1]. The required electrical conductivity can be easily achieved by using conductive fillers with a high aspect ratio, such as carbon nanotubes (CNTs), which already form the electrically conductive network at low concentrations.
As an alternative to melt mixing, the production of polymer nanocomposites from polymer solutions in organic solvents with SWCNTs and the simultaneous production of nanofibre composites by electrospinning and electrospraying of SWCNTs between nanofibres was the focus of this project (Fig. 1) [2]. The thermoelectric investigations show that the Seebeck coefficient is independent of rotation direction. In contrast, the electrical conductivity is higher in the direction of the rotational movement (vertical) than transverse to the rotation (horizontal).
References
[1] B. Krause, C. Barbier, J. Levente, M. Klaus, P. Pötschke Journal of Composites Science 2019, 3, 106.
[2] I. Borazan The Journal of The Textile Institute, 2023, 114, 1918-1923.