This invention concerns a method of manufacturing a highly conductive polytetrafluoroethylene sheet; a method of manufacturing a highly conductive unsintered polytetrafluoroethylene sheet: and a method of manufacturing a highly conductive sintered sheet. In the first method, a paste of polytetrafluoroethylene powder admixed with conductive substance and extrusion lubricant is extruded to preform an unsintered tube-like material, and at least one place on the circumference of this extruded material, the material is cut open longitudinally and the resulting sheet is calendered if necessary. The second method includes a sintering process for the sheet. This invention also concerns a highly conductive polytetrafluoroethylene sheet having a wide-width and long-length, which is obtained by the above-mentioned method. This sheet is not less than 170 mm in width and has variance of volume resistivity (conductivity) in the longitudinal direction, 10% or less, preferably 7% or less in the cross direction. This invention can provide a highly conductive wide-type PTFE sheet whose conductivity in the longitudinal direction is nearly uniform in the cross direction.

A catheter balloon or other expandable tubular medical device or component, having at least a first layer with a first section and a second section longitudinally compacted by more than the first section. In a presently preferred embodiment, the second section of the first layer extends at least in part along a central portion of the length of the first layer. The longitudinal compaction of the material of the first layer preferably results in a balloon or other expandable tubular medical device or component having improved performance characteristics such as compliance and dimensional stability. One aspect of the invention is directed to a method of longitudinally compacting a porous polymeric tube incrementally along the length of the tube, to compact sections of the tube.

According to the present invention, there is provided a hose assembly with an inner fluoropolymer layer having a somewhat smooth inner surface and an outer polyamide layer having an undulated surface.

A heat sealable tape of a copolymer of tetrafluoroethylene and at least about 15% by weight of a highly fluorinated monomer. The copolymer has a melt viscosity of no greater than about 1000 PaS at 372.degree. C. and an application temperature of no greater than about 250.degree. C. The invention further provides for a seam formed from two sections of sheet material, especially fabric, wherein each sheet has at least one fluoropolymer surface. The sections are sealed one to the other by application of heat sealable composition over one fluoropolymer surface of each section. The heat sealable composition comprises a copolymer of tetrafluoroethylene and at least about 15% by weight of a highly fluorinated monomer, the copolymer having a melt viscosity of no greater than about 1000 PaS at 372.degree. C. and an application temperature of no greater than about 250.degree. C. In preferred embodiments, building structures and manufacturing equipment are fabricated from sheet material having the seam formed from two sections of sheet material wherein each sheet has at least one fluoropolymer surface.

A method of making a catheter balloon, and a balloon catheter formed thereby, in which a layer of a catheter balloon is formed by decreasing the inner diameter of a first end section of a polymeric tube, so that the tube has a reduced diameter first end section with an inner diameter less than the inner diameter of a central section of the tube. The reduced diameter first end section of the tube is bonded to a catheter shaft to form at least a portion of a skirt section of the balloon, and the skirt section has an improved high rupture pressure.