Journal article
Mechanical properties of biaxially strained poly(L-lactide) tubes: Strain rate and temperature dependence
Department of Micro- and Nanotechnology, Technical University of Denmark1
Amphiphilic Polymers in Biological Sensing, Department of Micro- and Nanotechnology, Technical University of Denmark2
Department of Energy Conversion and Storage, Technical University of Denmark3
Imaging and Structural Analysis, Department of Energy Conversion and Storage, Technical University of Denmark4
Department of Wind Energy, Technical University of Denmark5
Composites Mechanics and Materials Mechanics, Department of Wind Energy, Technical University of Denmark6
Mixed Conductors, Department of Energy Conversion and Storage, Technical University of Denmark7
Poly(l-lactide) (PLLA) is a bioabsorbable polymer with high stiffness and strength compared to the other commercially available bioabsorbable polymers. The properties of PLLA can be improved by straining, causing deformation-mediated molecular orientation. PLLA tubes were biaxially strained above their Tg for improvement of their strength, in a two-step process (sequential straining).
Mechanical properties and crystal morphology were investigated as a function of processing strain rate and temperature. DSC revealed that a low processing strain rate allows molecular chain relaxation in the direction of strain and the crystallization is suppressed. Faster strain rates on the other hand suppress chain relaxation, and results in crystalline tubes.
The mechanical properties are influenced by both processing strain rate and temperature. Low strain rates allow chain relaxation resulting in the lowest strength and stiffness, whereas a larger stiffness and strength is achieved by increasing strain rate and temperature. Isotropic mechanical properties are only observed at high processing strain rates.
Language: | English |
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Year: | 2017 |
Pages: | 45192 |
ISSN: | 10974628 and 00218995 |
Types: | Journal article |
DOI: | 10.1002/app.45192 |
ORCIDs: | Andreasen, Jens Wenzel , Mikkelsen, Lars Pilgaard , Agersted, Karsten and Almdal, Kristoffer |