{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:05:25Z","timestamp":1760148325377,"version":"build-2065373602"},"reference-count":45,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2023,4,20]],"date-time":"2023-04-20T00:00:00Z","timestamp":1681948800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"FCT-Foundation for Science and Technology","doi-asserted-by":"publisher","award":["UID\/CTM\/00264\/2021","UIDB\/00264\/2020","UIDB\/04650\/2020-2023","ACT\/192023"],"award-info":[{"award-number":["UID\/CTM\/00264\/2021","UIDB\/00264\/2020","UIDB\/04650\/2020-2023","ACT\/192023"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"name":"FCT\/PIDDAC through the Strategic Funds project","award":["UID\/CTM\/00264\/2021","UIDB\/00264\/2020","UIDB\/04650\/2020-2023","ACT\/192023"],"award-info":[{"award-number":["UID\/CTM\/00264\/2021","UIDB\/00264\/2020","UIDB\/04650\/2020-2023","ACT\/192023"]}]},{"DOI":"10.13039\/501100002848","name":"Project ANID PIA Anillo","doi-asserted-by":"publisher","award":["UID\/CTM\/00264\/2021","UIDB\/00264\/2020","UIDB\/04650\/2020-2023","ACT\/192023"],"award-info":[{"award-number":["UID\/CTM\/00264\/2021","UIDB\/00264\/2020","UIDB\/04650\/2020-2023","ACT\/192023"]}],"id":[{"id":"10.13039\/501100002848","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J. Compos. Sci."],"abstract":"<jats:p>The electrical conductivity (\u03c3) and Seebeck coefficient (S) at temperatures from 40 \u00b0C to 100 \u00b0C of melt-processed polypropylene (PP) composites filled with 5 wt.% of industrial-grade carbon nanofibers (CNFs) is investigated. Transmission Electron Microscopy (TEM) of the two Pyrograf\u00ae III CNFs (PR 19 LHT XT and PR 24 LHT XT), used in the fabrication of the PP\/CNF composites (PP\/CNF 19 and PP\/CNF 24), reveals that CNFs PR 24 LHT XT show smaller diameters than CNFs PR 19 LHT XT. In addition, this grade (PR 24 LHT XT) presents higher levels of graphitization as deduced by Raman spectroscopy. Despite these structural differences, both Pyrograf\u00ae III grades present similar \u03c3 (T) and S (T) dependencies, whereby the S shows negative values (n-type character). However, the \u03c3 (T) and S (T) of their derivative PP\/CNF19 and PP\/CNF24 composites are not analogous. In particular, the PP\/CNF24 composite shows higher \u03c3 at the same content of CNFs. Thus, with an additionally slightly more negative S value, the PP\/CNF24 composites present a higher power factor (PF) and figure of merit (zT) than PP\/CNF19 composites at 40 \u00b0C. Moreover, while the \u03c3 (T) and S (T) of CNFs PR 19 LHT XT clearly drive the \u03c3 (T) and S (T) of its corresponding PP\/CNF19 composite, the S (T) of CNFs PR 24 LHT XT does not drive the S (T) observed in their corresponding PP\/CNF24 composite. Thus, it is inferred in PP\/CNF24 composites an unexpected electron donation (n-type doping) from the PP to the CNFs PR 24 LHT XT, which could be activated when PP\/CNF24 composites are subjected to that increase in temperature from 40 \u00b0C to 100 \u00b0C. All these findings are supported by theoretical modeling of \u03c3 (T) and S (T) with the ultimate aim of understanding the role of this particular type of commercial CNFs on the thermoelectrical properties of their PP\/CNF composites.<\/jats:p>","DOI":"10.3390\/jcs7040173","type":"journal-article","created":{"date-parts":[[2023,4,21]],"date-time":"2023-04-21T01:33:43Z","timestamp":1682040823000},"page":"173","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Comparative Thermoelectric Properties of Polypropylene Composites Melt-Processed Using Pyrograf\u00ae III Carbon Nanofibers"],"prefix":"10.3390","volume":"7","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4688-5794","authenticated-orcid":false,"given":"Antonio J.","family":"Paleo","sequence":"first","affiliation":[{"name":"2C2T-Centre for Textile Science and Technology, University of Minho, Campus de Azur\u00e9m, 4800-058 Guimar\u00e3es, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2892-1269","authenticated-orcid":false,"given":"Beate","family":"Krause","sequence":"additional","affiliation":[{"name":"Leibniz-Institut f\u00fcr Polymerforschung Dresden e.V. (IPF), Hohe Str. 6, 01069 Dresden, Germany"}]},{"given":"Ana R.","family":"Mendes","sequence":"additional","affiliation":[{"name":"SEMAT\/UM-Materials Characterization Services, University of Minho, 4804-533 Guimar\u00e3es, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5757-0096","authenticated-orcid":false,"given":"Carlos J.","family":"Tavares","sequence":"additional","affiliation":[{"name":"Physics Centre of Minho and Porto Universities (CF-UM-PT), University of Minho, 4804-533 Guimar\u00e3es, Portugal"}]},{"given":"Maria F.","family":"Cerqueira","sequence":"additional","affiliation":[{"name":"INL\u2014International Iberian Nanotechnology Laboratory, Av. Mestre, Jose Veiga, 4715-330 Braga, Portugal"},{"name":"CFUM\u2014Center of Physics of the University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal"}]},{"given":"Enrique","family":"Mu\u00f1oz","sequence":"additional","affiliation":[{"name":"Facultad de F\u00edsica, Pontificia Universidad Cat\u00f3lica de Chile, Santiago 7820436, Chile"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6392-7880","authenticated-orcid":false,"given":"Petra","family":"P\u00f6tschke","sequence":"additional","affiliation":[{"name":"Leibniz-Institut f\u00fcr Polymerforschung Dresden e.V. 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