METHOD FOR MAKING EPTFE AND STRUCTURE CONTAINING SUCH EPTFE, SUCH AS A VASCULAR GRAFT

摘要

A method for making a vascular graft includes providing a PTFE green tube extrudate (12) which is un-sintered, and then initially expanding the un-sintered extrudate (17) to produce an initial node and fibril micro-structure therein. This is followed by heating the extrudate to raise the temperature thereof for a time period of sufficient duration such that the extrudate is partially sintered. The partially sintered extrudate is subsequently expanded (25) to make the vascular graft. The subsequent expansion produces a subsequent node and fibril micro­structure in the vascular graft. An alternative method for making a vascular graft includes providing a PTFE green tube extrudate which is un-sintered, longitudinally expanding the un­sintered extrudate to form an ePTFE tube structure, and radially expanding the un-sintered ePTFE tube structure. ePTFE made according to the method is fabricated into various structures, such as tube structures, filament structures, and sheet structures.