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Radially expandable polytetrafluoroethylene

  • US 20040157024A1
  • Filed: 02/05/2004
  • Published: 08/12/2004
  • Est. Priority Date: 06/27/1994
  • Status: Active Grant
First Claim
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1. A method for producing a porous tube consisting essentially of highly crystalline polytetrafluoroethylene polymer, comprising the steps of (a) extruding a lubricant—

  • polytetrafluoroethylene resin blend to form a tubing having a longitudinal axis, a primary inner diameter, and a primary length;

    (b) heating the tubing to remove the lubricant;

    (c) stretching the tubing along said longitudinal axis to produce an elongated tubing having a secondary length greater than said primary length;

    (d) restraining said elongate tubing to prevent said elongate tubing from longitudinally contracting during sintering;

    (e) sintering said elongated tubing to produce a sintered tubing having a length substantially equivalent to said secondary length;

    (f) radially expanding said sintered tubing to produce radially expanded tubing have an expanded inner diameter greater than said primary inner diameter; and

    , (g) sintering said radially expanded tubing to contract said radially expanded tubing and produce a tubing having an inner diameter substantially equivalent to said primary inner diameter.

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