Effect of Annealing on Thermal and Dynamic Mechanical Properties of Poly(lactic acid)

Effect of Annealing on Thermal and Dynamic Mechanical Properties of Poly(lactic acid) | 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 Effect of Annealing on Thermal and Dynamic Mechanical Properties of Poly(lactic acid) Assia Zennaki, Latifa Zair, Khadidja Arabeche, Lina Benkraled, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1758641/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Effects of annealing temperature ( T a : 80-140°C) and time ( t a : 3-30 h) on the crystalline phase transition in poly(lactic acid) (PLA) were studied by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). In the DSC curves, the sample annealed at T a =80°C with time interval ( t a : 10-30 h) demonstrates a peculiarly small exothermal peak ( T exo ) around 130°C, just prior to the melting point, corresponding to the disorder-to-order ( a ’-to- a ) phase transition, while the sample annealed at temperature ( T a : 90-110°C) shows a double melting behavior considered as the a '- a phase transition. At T a >110°C, the a ′ -form of PLA was found to transform into the a one during the annealing process. The a ’- a phase transition around 100°C ( T a : 90-110°C), determined from the two melting peaks ( T m1 and T m2 ) as function of T a at different times t a , shows a good correlation with the substantial increase in the crystallinity rate ( X c ) with a maximum of 32% at T a =120°C. Towards low temperatures, the glass modulus E g reported by DMA thermograms, shows an important increase (~30 000 MPa) at T a =80°C for t a =3 h, due to the nucleation density extremely high in low PLA materials crystallization. After a sharp drop to 3 600 MPa at T a =110°C, a marked improvement of E g (15 900 MPa) is observed around T a =120°C for all samples, regardless of time t a , temperature region where PLA is usually molded in the industrial melt processing. This interesting effect (improvement of E g in range T a =100-120°C) can be correlated with the grow of crystallinity in the same domain of T a , and the a ’- a phase transition T a ( T a : 90-110 °C) determinate by the double T m melting DSC peak, which is confirmed by the increase of T g for T a =90-110°C. Poly(lactic acid) thermal properties mechanical properties annealing crystallization phase transition. Full Text Additional Declarations No competing interests reported. Supplementary Files SupplementpartMaschkeetal.pdf Cite Share Download PDF Status: Posted 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-1758641","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":113676541,"identity":"b98e358b-68a7-44a5-afe5-4af9e21ff890","order_by":0,"name":"Assia Zennaki","email":"","orcid":"","institution":"Université Aboubakr Belkaïd","correspondingAuthor":false,"prefix":"","firstName":"Assia","middleName":"","lastName":"Zennaki","suffix":""},{"id":113676542,"identity":"3dd416bd-f00e-463e-8c86-6adb686d713c","order_by":1,"name":"Latifa Zair","email":"","orcid":"","institution":"Université Aboubakr Belkaïd","correspondingAuthor":false,"prefix":"","firstName":"Latifa","middleName":"","lastName":"Zair","suffix":""},{"id":113676543,"identity":"42037ad8-8cdd-45a1-a8c6-a1b6f8c08775","order_by":2,"name":"Khadidja Arabeche","email":"","orcid":"","institution":"Université Aboubakr Belkaïd","correspondingAuthor":false,"prefix":"","firstName":"Khadidja","middleName":"","lastName":"Arabeche","suffix":""},{"id":113676544,"identity":"e04b8821-c5c7-4274-b781-1a768066ab5c","order_by":3,"name":"Lina Benkraled","email":"","orcid":"","institution":"Université Aboubakr Belkaïd","correspondingAuthor":false,"prefix":"","firstName":"Lina","middleName":"","lastName":"Benkraled","suffix":""},{"id":113676545,"identity":"7bfcea88-9aac-4e8b-b140-00b95d8beae3","order_by":4,"name":"Ulrich Maschke","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABEElEQVRIie3OMUvDQBTA8RcOLks06x2on+GKYB2CfhCXBCEuBhw7OBwUzqXFNZN+hXRStwsHugSzBro0S+eMFor0khZRuGZ2uP9yjwc/7gHYbP8xF0A6vBuxfgMApMcFOz8CcBZGgv6SeEtCRjw9sX0EfhG13YawnzB1UMvVK1z5j2pZp6MyenE9BuEd8XxAuDESl+XTApK0ioeDrJhHb+OW6MMoRyg1EgzKEZDwysO0FvMoU/jmqyVM+sp82I48l4Um358tCbtfLiVCvSSTt5jOuNQEyY4wMBOqST4VJJlV8RlN369PfwhRZnL4IVCzEkHyVKolndxfHGdlzqFZByf+w9hIdhHTsg/YbDabrbcNQ6FfcFSagSUAAAAASUVORK5CYII=","orcid":"","institution":"UMET – Unité Matériaux et Transformations, UMR 8207, Univ. Lille, CNRS, INRAE, Centrale Lille","correspondingAuthor":true,"prefix":"","firstName":"Ulrich","middleName":"","lastName":"Maschke","suffix":""},{"id":113676546,"identity":"d85d68de-98c8-43de-a646-8b84e6475622","order_by":5,"name":"Abdelkader Berrayah","email":"","orcid":"","institution":"Université Aboubakr Belkaïd","correspondingAuthor":false,"prefix":"","firstName":"Abdelkader","middleName":"","lastName":"Berrayah","suffix":""}],"badges":[],"createdAt":"2022-06-14 19:29:05","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-1758641/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-1758641/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":23018857,"identity":"2868051b-b6df-4b15-93d0-6b1941ec7164","added_by":"auto","created_at":"2022-06-23 19:04:12","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1604970,"visible":true,"origin":"","legend":"","description":"","filename":"Maschkeetal.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1758641/v1_covered.pdf"},{"id":23018856,"identity":"3eff6808-8c29-43b3-9708-83741bb83d33","added_by":"auto","created_at":"2022-06-23 19:03:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":379441,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementpartMaschkeetal.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1758641/v1/3eb920296c70ec98d4df945b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effect of Annealing on Thermal and Dynamic Mechanical Properties of Poly(lactic acid)","fulltext":[{"header":"Full Text","content":"This preprint is available for \u003ca href='/article/rs-1758641/latest.pdf' target='_blank'\u003edownload as a PDF\u003c/a\u003e."}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Poly(lactic acid), thermal properties, mechanical properties, annealing, crystallization, phase transition.","lastPublishedDoi":"10.21203/rs.3.rs-1758641/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1758641/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eEffects of annealing temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e: 80-140°C) and time (\u003cem\u003et\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e: 3-30 h) on the crystalline phase transition in poly(lactic acid) (PLA) were studied by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). In the DSC curves, the sample annealed at \u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e=80°C with time interval (\u003cem\u003et\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e: 10-30 h) demonstrates a peculiarly small exothermal peak (\u003cem\u003eT\u003c/em\u003e\u003csub\u003eexo\u003c/sub\u003e) around 130°C, just prior to the melting point, corresponding to the disorder-to-order (\u003cem\u003ea\u003c/em\u003e’-to-\u003cem\u003e a\u003c/em\u003e) phase transition, while the sample annealed at temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e: 90-110°C) shows a double melting behavior considered as the \u003cem\u003ea\u003c/em\u003e'-\u003cem\u003e a\u003c/em\u003e phase transition. At \u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e\u0026gt;110°C, the \u003cem\u003ea\u003c/em\u003e′ -form of PLA was found to transform into the a one during the annealing process. The \u003cem\u003ea\u003c/em\u003e’-\u003cem\u003e a\u003c/em\u003e \u0026nbsp;phase transition around 100°C (\u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e: 90-110°C), determined from the two melting peaks (\u003cem\u003eT\u003c/em\u003e\u003csub\u003em1 \u003c/sub\u003eand \u003cem\u003eT\u003c/em\u003e\u003csub\u003em2\u003c/sub\u003e) as function of \u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e at different times \u003cem\u003et\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e, shows a good correlation with the substantial increase in the crystallinity rate (\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003ec\u003c/em\u003e\u003c/sub\u003e) with\u003cem\u003e \u003c/em\u003ea maximum of 32% at \u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e=120°C. Towards low temperatures, the glass modulus \u003cem\u003eE\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e reported by DMA thermograms, shows an important increase (~30 000 MPa) at \u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e=80°C for \u003cem\u003et\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e=3 h, due to the nucleation density extremely high in low PLA materials crystallization. After a sharp drop to 3 600 MPa at \u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e=110°C, a marked improvement of \u003cem\u003eE\u003c/em\u003e\u003csub\u003eg \u003c/sub\u003e(15 900 MPa) is observed around \u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e=120°C for all samples, regardless of time \u003cem\u003et\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e, temperature region where PLA is usually molded in the industrial melt processing. This interesting effect (improvement of \u003cem\u003eE\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e in range \u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e=100-120°C) can be correlated with the grow of crystallinity in the same domain of \u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e, and the \u003cem\u003ea\u003c/em\u003e’-\u003cem\u003e a\u003c/em\u003e phase transition \u003cem\u003eT\u003c/em\u003e\u003csub\u003ea \u003c/sub\u003e(\u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e: 90-110 °C) determinate by the double \u003cem\u003eT\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e melting DSC peak, which is confirmed by the increase of \u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e for \u003cem\u003eT\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e=90-110°C.\u003c/p\u003e","manuscriptTitle":"Effect of Annealing on Thermal and Dynamic Mechanical Properties of Poly(lactic acid)","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-06-23 19:03:56","doi":"10.21203/rs.3.rs-1758641/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"39f53b44-07b3-44fc-b0fe-6dbaa8b71411","owner":[],"postedDate":"June 23rd, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2022-06-23T19:03:58+00:00","versionOfRecord":[],"versionCreatedAt":"2022-06-23 19:03:56","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1758641","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1758641","identity":"rs-1758641","version":["v1"]},"buildId":"_2-kVJe1T_tPrBINL-cwx","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}