{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,26]],"date-time":"2026-04-26T17:27:44Z","timestamp":1777224464386,"version":"3.51.4"},"reference-count":33,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2024,10,24]],"date-time":"2024-10-24T00:00:00Z","timestamp":1729728000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Sandwich panels are widely used in the naval and aerospace industries to withstand the normal tensile, compressive, and shear stresses associated with bending. The faces of sandwich composites are usually made of metals such as aluminum and, in some studies with composites, using a polymeric matrix, but there are no studies in the literature using a castor oil polyurethane matrix. The core of the panel must keep the faces apart and be rigid perpendicular to them. To begin the work, a study was carried out on the influence of alkaline treatment on sisal fibers to increase the fibers\u2019 adhesion to castor oil polyurethane. There are no relevant studies worldwide on the use of this resin and the adhesion of vegetable fibers to this polyurethane. In this work, a study was carried out through a three-point bending test of sandwich panels using faces of composite material with sisal fibers subjected to an alkaline treatment of 10% by weight of sodium hydroxide and an immersion time of 4 h in the dissolution, which was the best chemical treatment obtained initially in a castor oil polyurethane matrix. The honeycomb cores were made by 3D printer and in this study two different printing filament materials, PETG and PLA, and two different core heights were compared. As a result of a traction test, it was observed that sisal fibers with chemical treatment in a castor oil polyurethane matrix can be used in composites, although the stress levels obtained are 50% lower than the stresses obtained in other matrixes such as epoxy resin. The combination of sisal faces in a castor oil polyurethane matrix and honeycomb cores made in a 3D printer showed good properties, which allows the use of renewable, sustainable and less aggressive materials for the environment. In all tests, PETG was 21% to 32% stronger than PLA. Although there was no rupture in the test specimens, the PETG cores deformed 0.5% to 3.6% less than PLA. The composites with PLA were lighter, because the core density was 13.8% lower than the PETG cores. Increasing the height of the honeycomb increased its strength.<\/jats:p>","DOI":"10.3390\/polym16212980","type":"journal-article","created":{"date-parts":[[2024,10,24]],"date-time":"2024-10-24T05:47:33Z","timestamp":1729748853000},"page":"2980","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["The Evaluation of Sandwich Composite Materials with Vegetable Fibers in a Castor Oil Polyurethane Matrix with Their Faces and Honeycomb Core Made in a 3D Printer"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0754-2390","authenticated-orcid":false,"given":"Gilberto Garcia del","family":"Pino","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering, Higher School of Technology, Amazonas State University, Manaus 69050-020, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Abderrezak","family":"Bezazi","sequence":"additional","affiliation":[{"name":"Laboratoire de M\u00e9canique Appliqu\u00e9e des Nouveaux Mat\u00e9riaux (LMANM), University of Guelma, Guelma 24000, Algeria"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Antonio Claudio","family":"Kieling","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Higher School of Technology, Amazonas State University, Manaus 69050-020, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1155-0027","authenticated-orcid":false,"given":"Jos\u00e9 Costa de Macedo","family":"Neto","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Higher School of Technology, Amazonas State University, Manaus 69050-020, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8316-0012","authenticated-orcid":false,"given":"Sofia Dehaini","family":"Garcia","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Federal University of S\u00e3o Jo\u00e3o del Rei, S\u00e3o Jo\u00e3o del-Rei 36307-352, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1584-6901","authenticated-orcid":false,"given":"Jos\u00e9 Luis Valin","family":"Rivera","sequence":"additional","affiliation":[{"name":"Escuela de Ingenier\u00eda Mec\u00e1nica, Pontificia Universidad Cat\u00f3lica de Valpara\u00edso, Valpara\u00edso 2340025, Chile"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2339-3719","authenticated-orcid":false,"given":"Meyl\u00ed","family":"Valin Fern\u00e1ndez","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering (DIM), Faculty of Engineering (FI), University of Concepci\u00f3n, Concepci\u00f3n 4030000, Chile"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Aristides Rivera","family":"Torres","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, Higher School of Technology, Amazonas State University, Manaus 69050-020, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Francisco Rolando","family":"Valenzuela Diaz","sequence":"additional","affiliation":[{"name":"Department of Materials Engineering and Metallurgy, University of S\u00e3o Paulo, S\u00e3o Paulo 05508-220, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,10,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"86","DOI":"10.1080\/1023666X.2024.2316966","article-title":"Effect of extension speed on the mechanical performance of sisal and coir fiber bundles","volume":"29","author":"Omgba","year":"2024","journal-title":"Int. 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