Sequential biaxial strain of semi-crystalline tubes

Abstract

The present disclosure provides a processing method for a polymer material to create a medical device with improved mechanical properties. This method allows better tailoring of the material's mechanical properties, hence a device to withstand greater structural loads in vivo. The method comprises providing an extruded polymer tube having an initial diameter and an initial length along a longitudinal direction, and longitudinally, bi-directionally straining the extruded polymer tube in a mold from the initial length to an expanded or extended length. The mold comprises a plurality of stationary heating elements. After longitudinally straining the tube, it is radially expanding in the mold from the initial diameter to an expanded diameter.

1 - 17 . (canceled) 
     
     
         18 . A medical device comprising:
 a tubular body formed from an extruded polymer tube that is longitudinally strained in a mold, the extruded polymer tube having an initial diameter, an initial length, and a lumen therethrough along a longitudinal direction, wherein the extruded polymer tube is longitudinally strained from the initial length to an extended length, the extruded polymer tube being radially expanded in the mold wherein the extruded polymer tube is expanded from the initial diameter to an expanded diameter after the extruded polymer tube has been longitudinally strained, the tubular body having an elastic modulus in the longitudinal direction of above 3500 megapascals.   
     
     
         19 . The medical device of  claim 18  wherein the elastic modulus in the longitudinal direction is about 4000 megapascals. 
     
     
         20 . The medical device of  claim 18  wherein the tubular body has a yield stress in the longitudinal direction of above 90 megapascals. 
     
     
         21 . A medical device comprising:
 a tubular body formed from an extruded polymer tube that is longitudinally strained in a mold, the extruded polymer tube having an initial diameter, an initial length, and a lumen therethrough along a longitudinal direction, wherein the extruded polymer tube is longitudinally strained from the initial length to an extended length, the extruded polymer tube being radially expanded in the mold wherein the extruded polymer tube is expanded from the initial diameter to an expanded diameter after the extruded polymer tube has been longitudinally strained, the tubular body having an elastic modulus in the longitudinal direction of about 4000 megapascals.   
     
     
         22 . A medical device comprising:
 a tubular body formed from an extruded polymer tube that is longitudinally strained in a mold, the extruded polymer tube having an initial diameter, an initial length, and a lumen therethrough along a longitudinal direction, wherein the extruded polymer tube is longitudinally strained from the initial length to an extended length, the extruded polymer tube being radially expanded in the mold wherein the extruded polymer tube is expanded from the initial diameter to an expanded diameter after the extruded polymer tube has been longitudinally strained, the tubular body having an elastic modulus in the longitudinal direction of above 3500 megapascals and a yield stress in the longitudinal direction of above 90 megapascals.