Issue 48

C.M.S. Vincente et alii, Frattura ed Integrità Strutturale, 48 (2019) 748-756; DOI: 10.3221/IGF-ESIS.48.68 748 Effect of protective coatings on the water absorption and mechanical properties of 3D printed PLA Carlos M. S. Vicente, João Fernandes, Luís Reis* IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049–001 Lisboa, Portugal carlos.vicente@tecnico.ulisboa.pt , https://orcid.org/0000-0003-0701-190 joaofranciscomirandafernandes@gmail.com *luis.g.reis@tecnico.ulisboa.pt , http://orcid.org/0000-0001-9848-9569 Augusto Moita de Deus, M.F. Vaz IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049–001 Lisboa, Portugal and CeFEMA, Instituto Superior Técnico, Universidade de Lisboa, 1049–001 Lisboa, Portugal amd@tecnico.ulisboa.pt , http://orcid.org/0000-0002-0451-6245 fatima.vaz@tecnico.ulisboa.pt, http://orcid.org/0000-0003-1629-523X Marco Leite UNIDEMI, Departamento de Engenharia Mecânica e Industrial, Faculty of Science and Technology, New University of Lisbon, Campus da Faculdade de Ciência e Tecnologia, 2829–516 Caparica, Portugal marcoleite@tecnico.ulisboa.pt , http://orcid.org/0000-0002-0319-4475 A BSTRACT . This work aims to study the influence of protective coatings on the water absorption and mechanical properties of 3D printed poly–lactic acid (PLA) parts. The PLA parts were fabricated with different levels of the 3D printing process parameters, aiming to define samples with distinct strength and ductility/toughness characteristics. Water absorption tests following the standard ASTM D570–98 were performed on uncoated and coated PLA specimens. The effectiveness of two protective coatings based on acrylic and polyurethane varnish on reducing water absorption was evaluated. Both protective coatings have shown being effective on preventing water absorption by the PLA, with polyurethane presenting the best performance reducing water absorption by 38%. Tensile tests were carried out to determine the ultimate tensile strength, elastic modulus, yield tensile strength, fracture strain and toughness of specimens, before and after the application of protective coatings. The polyurethane protective coating also benefits the tensile properties of PLA parts, increasing the strength and ductility/toughness characteristics of specimens up to 24%. Citation: Vincente, C.M.S., Fernandes, J., Reis, L., de Deus, A. M. Vaz, M. F., Leite, M., Effect of protective coatings on the water absorption and mechanical properties of 3D printed PLA, Frattura ed Integrità Strutturale, 48 (2019) 748-756. Received: 13.02.2019 Accepted: 13.03.2019 Published: 15.04.2019 Copyright: © 2019 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.