Medical Device Fabrication Process Including Strain Induced Crystallization With Enhanced Crystallization
AssigneeAbbott Cardiovascular Systems Inc.
InventorsLothar W. Kleiner, Fuh-Wei Tang
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Abstract
Methods of fabricating a polymeric implantable device, such as a stent, with improved fracture toughness through annealing a polymer construct below the glass transition temperature of the polymer of the construct prior to a deformation step are disclosed herein. The deformation of the construct induces crystallization in the polymer construct through strain-induced crystallization. The annealing of the polymer construct accelerates the crystallization induced during the deformation and results in an increase in crystallite density with smaller crystallites as compared to deformation of a tube that has not been annealed. A stent scaffolding is then made from the deformed tube.
Claims13
A method of making a stent comprising:
- annealing an extruded PLLA tube at a temperature greater than 37° C. and less than or equal to Tg,midpoint of the PLLA extruded tube;
- wherein the PLLA tube is annealed for a selected annealing time greater than 1 min;
- wherein the annealing increases the nucleation density of the PLLA tube;
- followed by radially expanding the PLLA tube,
- wherein the radial expansion induces crystallization in the PLLA tube,
- wherein the increase in nucleation density due to the annealing results in the formation of a higher crystallite density and a decrease in the size of the crystallites as compared to tube that has not been annealed;
- and
- fabricating a stent scaffolding from the expanded PLLA tube.
Dependencies are inferred from the claim text.