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

Abstract

The results showed the dramatic influence of the plasticizer content and sterilization procedure on the mechanical properties of the material. Laser cutting had a lesser effect. Hence the effects of processing and sterilization must not be overlooked in the material selection and design phases of the development process leading to clinical use. Altogether, the results of these studies provide a clearer understanding of the complex interaction between the laser machining process and terminal sterilization on the primary mechanical properties of PLLA and PLLA plasticized with TEC.

Composite Material Stent Comprising Metallic and Non-metallic Materials

“…A common bioabsorbable material for this purpose is poly-l-lactic acid (PLLA), which has been widely used as a surgical suture material, and its biocompatibility and degradability in the human body has been established (Isotalo et al, 2002;Zilberman et al 2005). However, the physical properties of PLLA fibers, such as tensile strength and elasticity, are inferior to metallic wires (Grabow et al, 2005); therefore, the potential uses of this material in stents are limited. Under these circumstances, the purpose of our study was to improve the retrievability of metallic knitted stents, and for this purpose, we produced a composite material stent comprising bioabsorbable fiber and metallic wire.…”

Investigation of Bauschinger effect in thermo-plastic polymers for biodegradable stents

“…The combined uniaxial tensile/compression tests and compression tests without prior loading for the investigation of Bauschinger effect were conducted with two biodegradable thermoplastic polymers used in stent applications: poly(L-lactic acid) (PLLA) and a PLLA based blend [4,5]. The cylindrical specimens were fabricated by melt extrusion using a HAAKE MiniLab II (Thermo Fisher Scientific, Karlsruhe, Germany) with two different extrusion dies that lead to resulting diameters of 2,76±0,20 mm (combined tension/compression) and 1,50±0,02 mm (compression only).…”

Biodegradable microfibrillar polymer-polymer composites from poly(L-lactic acid)/poly(glycolic acid)

“…Poly(L-lactic acid), PLLA, is a very prominent material in biodegradable stent material development but its major disadvantage is that it is brittle [9]. Ductility is required during balloon expansion in order for the stent to undergo sufficient plastic deformation without fracturing [10]. It is possible to modify PLLA via plasticiser addition or blending with rubbery polymers to produce a ductile material.…”

“…It is possible to modify PLLA via plasticiser addition or blending with rubbery polymers to produce a ductile material. Grabow and coworkers [10][11][12] have blended PLLA with tri-ethyl citrate (TEC), poly(!-caprolactone) (PCL) and poly(4-hydroxybutyrate) (P4HB) for the intended application as biodegradable stent materials. Significant reduction in elastic moduli resulted (~50% in the cases of PLLA/ P4HB and PLLA/PCL/TEC blends [11,12] and creep resistance of PLLA/TEC was reported to have greatly reduced by 1-2 orders of magnitude [10].…”

“…Grabow and coworkers [10][11][12] have blended PLLA with tri-ethyl citrate (TEC), poly(!-caprolactone) (PCL) and poly(4-hydroxybutyrate) (P4HB) for the intended application as biodegradable stent materials. Significant reduction in elastic moduli resulted (~50% in the cases of PLLA/ P4HB and PLLA/PCL/TEC blends [11,12] and creep resistance of PLLA/TEC was reported to have greatly reduced by 1-2 orders of magnitude [10]. Blends of PLLA and poly(butylene succinate) (PBS) have been investigated by the authors and although they exhibit favourable mechanical properties, creep resistance reduces rapidly during degradation [13].…”