Abstract: A method of making an expanded polytetrafluoroethylene (ePTFE) membrane including the steps of: providing an unsintered or partially sintered ePTFE membrane; matting the unsintered or partially sintered ePTFE membrane; and immediately thereafter, sintering the matted ePTFE membrane. A method for making ePTFE tubes includes the steps of: providing an unsintered or partially sintered ePTFE membrane; wrapping the ePTFE membrane around a mandrel or form tool to form an ePTFE tube; matting the ePTFE tube; immediately thereafter, sintering the matted ePTFE tube; and removing the sintered ePTFE tube from the mandrel or form tool.

Abstract: A method for making a thin walled ePTFE tube having improved axial and radial strength includes the steps of: providing an unsintered or partially sintered ePTFE membrane; wrapping the ePTFE membrane around a mandrel or form tool to form an ePTFE tube; matting the ePTFE tube; immediately thereafter, sintering the matted ePTFE tube; removing the sintered ePTFE tube from the mandrel or form tool; stretching the sintered ePTFE tube in the axial direction; stretching the ePTFE tube in the radial direction over a second mandrel that is greater in diameter than the reduced axially stretched diameter, but less than the first mandrel diameter; overwrapping the second mandrel with a second ePTFE membrane; matting the ePTFE tube; immediately thereafter, sintering the matted ePTFE tube; and removing the sintered ePTFE tube from the second mandrel or form tool.