Post-Print Annealing: A Simple Strategy for Enhancing Adhesion in FDM-printed PLA-SMA Composites

Post-Print Annealing: A Simple Strategy for Enhancing Adhesion in FDM-printed PLA-SMA Composites | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Post-Print Annealing: A Simple Strategy for Enhancing Adhesion in FDM-printed PLA-SMA Composites Gregorio Pisaneschi, Emanuele Maccaferri, Laura Tartarini, Nicola Sancisi, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7454600/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 25 Feb, 2026 Read the published version in Smart Materials and Structures → Version 1 posted You are reading this latest preprint version Abstract Embedding Shape Memory Alloy (SMA) wires within 3D printed polymers enables 4D printing, but achieving strong interfacial adhesion is challenging without complex surface treatments. This study aims to investigate a simple post-print annealing strategy to enhance the adhesion between SMA wires and 3D-printed artefacts. SMA wires were embedded in FDM-printed PLA cylinders. A full factorial Design of Experiments was conducted, varying annealing temperatures (90, 110, 130 °C) and time (30, 60, 90 min). Adhesion was quantified via pull-out tests measuring Interfacial Shear Strength (ISS). Volumetric changes and degree of crystallinity by Differential Scanning Calorimetry were assessed. Tensile tests evaluated annealing effects on PLA properties. Annealing temperature significantly increased ISS, driven by increased PLA crystallinity (up to ≈ 49.2 %) and volumetric shrinkage (≈ 1.2 %). Annealing time had a negligible effect. Optimal conditions (130 °C, 60 min) achieved a significant increase in pull-out force for annealed specimens (ISS ≈ 0.8 MPa) compared to not annealed ones (ISS ≈ 0.3 MPa). Tensile tests on PLA revealed that annealing increased Young’s Modulus with increased temperatures but decreased ductility and tensile strength. Prolonged annealing (130 °C, 90 min) showed slightly reduced ISS, potentially due to polymer relaxation/degradation. This easily implementable annealing method offers a way to create more robust and reliable 4D printed SMA-polymer actuators and composites using standard FDM printers. Shape Memory Alloy (SMA) Polylactic acid (PLA) Fused Deposition Modelling (FDM) Annealing Adhesion Interfacial Shear Strength (ISS) Full Text Additional Declarations No competing interests reported. Supplementary Files SupplementaryFile.pdf Cite Share Download PDF Status: Published Journal Publication published 25 Feb, 2026 Read the published version in Smart Materials and Structures → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7454600","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":523754154,"identity":"7a6a50d6-de47-403d-a280-c64586654107","order_by":0,"name":"Gregorio 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