Mechanical Properties of Laser Cut Poly(L-Lactide) Micro-Specimens: Implications for Stent Design, Manufacture, and Sterilization

[+] Author and Article Information
Niels Grabow, Martin Schlun, Katrin Sternberg, Nico Hakansson, Sven Kramer, Klaus-Peter Schmitz

University of Rostock, Institute for Biomedical Engineering, Ernst-Heydemann-Str. 6, D-18057 Rostock, Germany

J Biomech Eng 127(1), 25-31 (Mar 08, 2005) (7 pages) doi:10.1115/1.1835349 History: Received January 23, 2004; Revised September 03, 2004; Online March 08, 2005
Copyright © 2005 by ASME
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Electron micrograph of a resorbable vascular stent prototype in the undeployed state (I.D.=1.4 mm)
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Finite element model of a deployed stent (I.D.=3.5 mm). Higher local plastic strains are indicated by lighter shades.
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Shouldered double bar micro-specimen as used in the mechanical and thermo-mechanical tests. Note the laser cut between the two struts (each having a width of approx. 300 μm) in the specimen mid-section.
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Polarization micrograph of a mechanical test specimen cross section. Arrows point to the bulk material and the laser affected edge zones.
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Typical stress-strain curves of PLLA/TEC 90/10 (Mw=260.000 g/mol) as a function of deformation speed
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Typical retardation curves, illustrating the influence of TEC on the creep and relaxation behavior of the material. Load during creep=10 MPa. Note the logarithmic ordinate scale.
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Typical modulus—temperature relationship for pure PLLA and PLLA/TEC. The addition of the plasticizer TEC produces a shift of the glass transition range towards lower temperatures, resulting in a lower elastic modulus at 37°C.
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Degree of crystallinity as a function of the leached TEC content [PLLA (100) and leached PLLA/TEC (95/5,90/10,85/15)]



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