Study on the thermoelectric properties of PVDF/MWCNT and PVDF/GNP composite foam

Abstract

Always cite the published version, so the author(s) will receive recognition through services that track citation counts, e.g. Scopus. If you need to cite the page number of the author manuscript from TSpace because you cannot access the published version, then cite the TSpace version in addition to the published version using the permanent URI (handle) found on the record page. Abstract. Thermoelectric effect is defined as the revisable translation between thermal and electrical energy. In this paper, we investigate the properties of p-type poly(vinylidene fluoride) (PVDF) based polymer composite foams that can be used in next generation energy harvesting applications. The composites were created via continuous melt blending method. Multi-walled carbon nanotubes (MWCNTs) and graphene nano-platelets (GNPs) were used as secondary phases to strengthen the electrical conductivity of the composites. Foam structures were later generated via super-critical carbon dioxide saturation method. We study the material properties between solid and foam samples; the results indicate a dramatic increase in overall thermoelectric properties for GNP foamed samples. We also report at least an order decreased in thermal conductivity which is in favor of thermoelectric effect. An unexpected drop in electrical conductivity was observed after the foaming process and can be explained by large volumetric expansion of the foam. Finally we report the Seebeck coefficient for both types of composite foams: 11 μV/K for 5 wt% MWCNT/PVDF foam and 58 μV/K for 15 wt% GNP/PVDF foam. IntroductionThermoelectric (TE) effect is known as the direct conversion between electrical and thermal energy and such effect can be explained by three different phenomena: Seebeck effect, Peliter effect, and Thomson effect. When a temperature gradient is applied to a circuit that consists of two different electric conductors, a small current can be observed which is called the Seebeck effect. The opposite phenomenon is called the Peliter effect, of which the junctions of the two conductors may either absorb or release heat when a voltage is supplied to the circuit. Lastly, the Thomson Effect states that when an electric current is passing through a conductor, certain amount of heat (Thomson heat) would be released or absorbed by the material and such heat is does not include the non-reversible Joule heating which is generated from the electric resistance nature of the material [1]. Seebeck effect is currently being implemented in verity types of temperature sensors or thermocouples [2] while the Peliter effect can be applied in different types of heat engines and coolers [3]. Other than temperature sensors, Seebeck effect also being widely researched for energy harvesting

Screening of Different Carbon Nanotubes in Melt-Mixed Polymer Composites with Different Polymer Matrices for Their Thermoelectrical Properties

“…The TE results for PVDF/CNT composites can be compared with some values from the literature. Sun et al [4] used the same type of PVDF and MWCNTs and the same preparation method for composites, namely melt compounding using a microcompounder DSM15 but with different melt mixing conditions than in our study. The measured S-values with 10 µV/K are slightly lower than in our investigation with 14.3 µV/K.…”

“…In one of the first studies on the TE performance of melt-processed polymer nanocomposites, Antar et al [3] reported poly(lactic acid) (PLA)/multi-walled CNT (MWCNT)/expanded graphite (EG) materials, in which the highest Seebeck coefficient was 17 µV/K at 32 vol % EG and the highest power factor 9.6 × 10 −2 µW/(m•K 2 ) at 18 vol % MWCNTs. Sun et al [4] reported on poly (vinylidene fluoride) (PVDF) composites filled with MWCNTs or graphite nanoplatelets (GNPs) as solid sample as well as foam. The Seebeck coefficients for solids were found to be 10 µV/K (PVDF/2 or 5 wt % MWCNT) and around 25 µV/K (PVDF/5-15 wt % GNP).…”

Boron Doping of SWCNTs as a Way to Enhance the Thermoelectric Properties of Melt-Mixed Polypropylene/SWCNT Composites

“…Namely, it can be easily upscaled and it is more environmentally friendly as no solvents are needed. Examples of this new kind of melt-mixed composites are polypropylene (PP) composites filled with single-walled carbon nanotubes (SWCNT) [6][7][8][9][10], polyetherimide/SWCNT nanocomposites [11], polycarbonate/multi-walled carbon nanotube (MWCNT) composites [12][13][14], polylactic acid (PLA)-based composites containing Bi 0.5 Sb 1.5 Te 3 and/or MWCNTs [15], PLA filled with MWCNT and/or expanded graphite [16], and poly(vinylidene fluoride) (PVDF)-based polymer composite foams with MWCNTs or GNPs [17]. In a recent paper, screening of different kinds of CNTs in different polymeric matrices was performed, showing that a variety of TE properties can be achieved when varying CNT and polymer type [18].…”

Lignin Doped Carbon Nanotube Yarns for Improved Thermoelectric Efficiency

“…The only exception is MWCNT-PDDA/MWCNT-DOC/PEDOT, which exhibits slightly higher PF than that of CNTY/lignin in the present study, due to the high content of PEDOT, and the combination of LbL assembly with electrochemical polymerization to create synergy capable of producing a high power factor. [16] [27] MWCNT/ PVP Mixing 0.6 [28] PEI/MWCNT/ PVP Mixing 1.98 [28] P3HT/MWCNT Mixing 6 [29] WPU/MWCNT/PEDOT:PSS Mixing 1.41 [30] PEDOT:PSS/MWCNT In situ polymerization 2.29 × 10 −1 [31] MWCNT/Nafion Mixing 0.75 [32] MWCNT-PDDA/MWCNT-DOC/PEDOT LbL + In situ polymerization 155 [16] www.advancedsciencenews.com © 2020 Wiley-VCH GmbH…”