Abstract: A liquid leak detecting sensor in the form of a coaxial cable assembly is provided in which means are provided for enhancing the passage of leaks from the outer surface of the outer conductor into the sensing layer which separates the inner and outer conductors. The change in permittivity of the sensing layer caused by the leak enables rapid detection of the location of the leak along the cable.

Abstract: A sheet of porous resinous material, particularly polytetrafluoroethylene, having a multiplicity of holes formed therethrough. The holes are provided in a plurality of rows extending along the length of the sheet. The sheet has a smaller thickness in the area extending along each row of holes than in its remaining portions.

Abstract: A composite laminated article is provided, useful for printed circuit boards in transmission of electrical signals in the high frequency range of the order of 10 GHz, comprising a layer of expanded, porous polytetrafluoroethylene (PTFE), maintained in a fully stretched state, affixed firmly to a solid substrate layer. The composite is formed by stretching extruded, unsintered PTFE, after removal of lubricant, holding the stretched PTFE in its fully stretched state, and bonding the stretched PTFE to a substrate. The porous PTFE layer in this composite has unexpectedly high compression resistance.

Abstract: A transmission line is provided, at least a portion of the wave energy transmitting part of the line being made of a dielectric material shaped to create a physical condition which preserves the deflected wave surface of the electromagnetic wave along the portion of the transmission line. The physical condition for preserving the deflected wave surface is formed by providing at least one linear portion which retards the speed of energy transmission so as to prevent the rotation of the electric field surface of the electromagnetic wave. The wave energy transmitting portion composed of dielectric material is preferably made to have an oval cross-section in which the ratio between the major axis and the minor axis has a value not lower than 4/3. Alternatively, the wave energy transmitting portion can be made to have a rectangular cross-section.

Abstract: A shaped article having a synthetic resinous body and a thin fluoropolymer weld layer on its surface is formed by a process which comprises heating a heat conductive metallic core member, forming a thin fluoropolymer weld layer on the surface of the core member, treating the exposed surface of the fluoropolymer layer, forming a synthetic resinous body on the outer, treated surface of the fluoropolymer layer and removing the core member, such as by dissolving. In the shaped article thus produced, a thin fluoropolymer weld layer is formed on the surface of the synthetic resinous body, and the thickness of the fluoropolymer coating can be reduced. This permits the production of shaped articles at low cost and having high mechanical strength, even for complicated shapes. According to the invention, it is possible to produce articles having complex shapes such as corrosion resistant vessels, molds having good release characteristics, and so forth, at a comparatively low cost.

Abstract: A dielectric waveguide in cable form fabricated from polytetrafluoroethylene. An embodiment of cable is a composite of partially sintered PTFE and sintered and unsintered expanded PTFE arranged in such a fashion that the specific gravity of cable decreases from the core to the outer surface.

Abstract: Reinforced easily moldable plastics are provided wherein particles of stretched porous polymer are incorporated into a plastic molding resin material to improve its physical properties without detracting from moldability. Particles or fragments of porous stretched forms of polyethylene, polypropylene, or polytetrafluoroethylene, are incorporated into a matrix of polytetrafluoroethylene polyvinylidene fluoride, or a copolymer of tetrafluoroethylene with perfluoroalkyl vinyl ether, hexafluoropropylene, ethylene, or trifluorochloroethylene.

Abstract: An improved flat cable in which parallel, spaced conductors are embedded in an expanded, porous polytetrafluoroethylene insulation and then placed between layers of polytetrafluoroethylene having a higher dielectric constant than the porous insulation. The dielectric constant between conductors can be varied.

Abstract: A new strip line cable is provided comprising a dielectric in tape form made of a porous, crystalline polymer and one or more pairs of electrical conductors, each pair of conductors having one conductor located on one side of said tape and the other conductor located on the opposite side of said tape and in substantially parallel relationship to the first conductor of the pair, the pairs of conductors being arranged in substantially parallel transverse relationship across said tape, and insulating layers made of a suitable non-porous plastic material placed over the conductors to affix them to said dielectric tape and encapsulate the cable assembly. The preferred tape dielectric is expanded, porous polytetrafluoroethylene.

Abstract: A melt-molded foamed plastic composition comprised of a tetrafluoroethylene-perfluoroalkyl vinyl ether resin matrix in which is admixed stretched porous fragments of polytetrafluoroethylene.

Abstract: A novel flat cable which has a number of parallel spaced conductors with tape segments having a conductive and insulative side woven between them at various positions along the length of the conductors. The weaving generally being done so that the conductive side touches alternate conductors. The whole complex may be encased in an outer insulation.

Abstract: A liquid leak detecting device is provided comprising at least two electrical conductors arranged in parallel and separated from each other by a material comprised of continuously porous polytetrafluoroethylene containing an electroconductive material within its pores.