Goutianos, Stergios

Sørensen, Bent F.

Van der Schueren, Lien

The growing public concern and new environmental legislations are driving forces for new materials with less environmental impact during the entire life cycle. As a result, biobased and biodegradable polymers have been extensively studied with Poly(lactic acid) (PLA) being one of the most promising biopolymer due to its attractive mechanical properties, the low amount of energy needed for production and its biodegradability [1]. Due to its brittleness, however, PLA is reinforced with fibres (e.g. natural fibres) to improve its mechanical and thermal properties [2]. Despite the use of natural fibres, there are issues with recycling of these composites. An alternative approach is the concept of “self-reinforced polymer” composites where the polymer matrix is reinforced with oriented fibres of the same polymer [3]. These materials are fully recyclable since there is no need to separate the fibres from the matrix.In the present work, we produce highly oriented fibres from PLA pellets by extrusion followed by solid state drawing. The PLA matrix is also in the form of fibres but has a lower melting point. Commingling the two types of fibres, results in hybrid yarns that can be wound to produce unidirectional sheets (after consolidation) or woven into fabrics, which can be subsequently consolidated to sheets. The consolidation temperature is lower than the melting point of the highly oriented fibres, which will remain intact, but higher than the melting point of the low melting fibres. In this way, a self-reinforced PLA composite can be produced.The stiffness of the self-reinforced PLA composites is significantly higher than the pure PLA material and competes with self-reinforced composites based on fossil hydrocarbon sourced polymers such as all-polypropylene composites. However, the strength of the self-reinforced PLA composites is still relatively low and needs to be improved.For this reason, the tensile response of the self-reinforced PLA composites is characterised in situ in order to identify the failure mechanisms and more importantly the sequence of damage development (including load levels). The tests are performed inside the chamber of an environmental scanning electron microscope under vapour pressure mode to minimise charging of cracks upon loading. Based on the experimental results, suggestions are drawn for optimising the mechanical properties (strength) of the self-reinforced PLA composites i.e. combination of fibre, matrix and interface properties

Online Research Database In Technology

  General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.   Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal  If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.         Downloaded from orbit.dtu.dk on: Mar 29, 2019In situ identification of the failure mechanisms in self-reinforced poly(lactic acid)compositesGoutianos, Stergios; Sørensen, Bent F.; Van der Schueren, LienPublication date:2018Document VersionPeer reviewed versionLink back to DTU OrbitCitation (APA):Goutianos, S., Sørensen, B. F., & Van der Schueren, L. (2018). In situ identification of the failure mechanisms inself-reinforced poly(lactic acid) composites. Abstract from ESMC 2018 – 10th European Solid MechanicsConference, Bologna, Italy.In situ identification of the failure mechanisms in self-reinforced poly(lactic acid) composites  Stergios Goutianos1, Bent F. Sørensen1, Lien Van der Schueren2 1Department of Wind Energy, Technical University of Denmark, Roskilde, Denmark E-mail: gout@dtu.dk, bsqr@dtu.dk  2 Centexbel Textile Research Center, Gent, Belgium  E-mail: Lien.VanderSchueren@centexbel.be  Keywords:  self-reinforced polymer composites, matrix crazing, fibre splitting,   The growing public concern and new environmental legislations are driving forces for new materials with less environmental impact during the entire life cycle. As a result, biobased and biodegradable polymers have been extensively studied with Poly(lactic acid) (PLA) being one of the most promising biopolymer due to its attractive mechanical properties, the low amount of energy needed for production and its biodegradability [1]. Due to its brittleness, however, PLA is reinforced with fibres (e.g. natural fibres) to improve its mechanical and thermal properties [2]. Despite the use of natural fibres, there are issues with recycling of these composites. An alternative approach is the concept of “self-reinforced polymer” composites where the polymer matrix is reinforced with oriented fibres of the same polymer [3]. These materials are fully recyclable since there is no need to separate the fibres from the matrix. In the present work, we produce highly oriented fibres from PLA pellets by extrusion followed by solid state drawing. The PLA matrix is also in the form of fibres but has a lower melting point. Commingling the two types of fibres, results in hybrid yarns that can be wound to produce unidirectional sheets (after consolidation) or woven into fabrics, which can be subsequently consolidated to sheets. The consolidation temperature is lower than the melting point of the highly oriented fibres, which will remain intact, but higher than the melting point of the low melting fibres. In this way, a self-reinforced PLA composite can be produced. The stiffness of the self-reinforced PLA composites is significantly higher than the pure PLA material and competes with self-reinforced composites based on fossil hydrocarbon sourced polymers such as all-polypropylene composites. However, the strength of the self-reinforced PLA composites is still relatively low and needs to be improved. For this reason, the tensile response of the self-reinforced PLA composites is characterised in situ in order to identify the failure mechanisms and more importantly the sequence of damage development (including load levels). The tests are performed inside the chamber of an environmental scanning electron microscope under vapour pressure mode to minimise charging of cracks upon loading. Based on the experimental results, suggestions are drawn for optimising the mechanical properties (strength) of the self-reinforced PLA composites i.e. combination of fibre, matrix and interface properties.  References [1] Auras R., Harte B. and Selke S., “An overview of polylactides as packaging materials”, Macromolecular Bioscience, Vol 4, page 835-864 (2004). [2] Berglund L.A. and Peijs T., “Cellulose biocomposites-from bulk moldings to nanostructured systems”, MRS Bulletin, Vol 35, page 201-207 (2010). [3] Ward I. and Hine P., "The science and technology of hot compaction", Polymer, Vol 45, page 1413-1427 (2004). 

In situ identification of the failure mechanisms in self-reinforced poly(lactic acid) composites

http://orbit.dtu.dk/ws/files/162273335/8_abstract.pdf

In situ identification of the failure mechanisms in self-reinforced poly(lactic acid) composites

Abstract

Similar works

Full text

Available Versions

Online Research Database In Technology