resumo
The thermoelectric properties, at temperatures from 30 degrees C to 100 degrees 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 degrees C, the PEEK/CNF composites show an electrical conductivity (sigma) of similar to 27 S m(-1) and a Seebeck coefficient (S) of -3.4 mu V 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 (E-F) 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 mu V K-1), is attributed to a slight electron withdrawing from the external layers of CNFs by the PEEK matrix. At temperatures from 30 degrees C to 100 degrees C, the sigma (T) of PEEK/CNF composites, in contrast to the sigma (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.
palavras-chave
CARBON NANOTUBES; CONDUCTIVITY; SINGLE; THERMOPOWER; TRANSPORT; BEHAVIOR; POWER
categoria
Polymer Science
autores
Paleo, AJ; Krause, B; Soares, D; Melle-Franco, M; Munoz, E; Potschke, P; Rocha, AM
nossos autores
Manuel Melle-Franco
Investigador PrincipalProjectos
Projeto de Investigação Exploratória: Manuel Melle (IF Manuel Melle)
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
A. J. Paleo gratefully acknowledges support from FCT-Foundation for Science and Technology by the project UID/CTM/00264/2021 of 2C2T under the COMPETE and FCT/MCTES (PIDDAC) cofinanced by FEDER through the PT2020 program and plurianual 2020-2023 Project UIDB/00264/2020. E. Munoz acknowledges financial support from ANID Anillo ACT/192023 and Fondecyt No 1190361. M. Melle-Franco acknowledges support from the project IF/00894/2015 and within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC).