Controlling crystalline morphology of a bioabsorbable stent

摘要

Methods to expand polymer tubing with desirable or optimum morphology and mechanical properties for stem manufacture and fabrication of a stent therefrom are disclosed.

主权项

1. A method for fabricating stent comprising:
providing a PLLA tube disposed within a cylindrical mold; heating the mold and the tube to a tube deformation temperature with a heat source translating along the cylindrical axis of the mold and the tube, wherein the heat source translation rate is between 0.2-1.2 mm/s and the tube deformation temperature is 84° C.; increasing a pressure inside the tube; allowing the increased pressure in the tube to radially expand the tube against the inner surface of the mold, wherein the radial expansion propagates along the cylindrical axis of the mold and tube as the heat source translates along the cylindrical axis; applying a tensile force to the tube along the cylindrical axis during the radial expansion to axially elongate the tube during the radial expansion; wherein the radial and axial draw ratios are 400% and 20%, respectively, to produce an expanded tube having an increased homogeneity in a mechanical property over a wall thickness of the expanded tube; and forming a stent pattern in the axially expanded and radially deformed tube.