Abstract: An improved gasket particularly suitable for use in sensitive environments is disclosed. The preferred gasket of the present invention comprises at least one layer of a composite material of porous polytetrafluoroethylene (PTFE) polymer and resilient expandable microspheres. The composite material provides a number of significant advantages over existing PTFE and similar clean gaskets, including better seal under less compressive pressure, sufficient resilience to permit reuse, and retained porosity--allowing pressure equalization in the equipment to occur through the gasket itself.

Abstract: Microporous membranes are described and characterized as having a morphological microstructure of very highly elongated nodes interconnected by fibrils which form a structural network of voids or pores through the spaces between the nodes and fibrils, which voids or pores extend from one side of the membrane to the other. The membranes are highly uniform in terms of mass per volume, have very high strength and a very open microstructure.

Abstract: The present invention provides improved compositions of expanded polytetrafluoroethylene (PTFE) and similar polymers and methods for forming and using such compositions. In its preferred embodiment, the present invention employs a mixture of PTFE and expandable thermoplastic microspheres. Through application of an energy source to the mixture, a coherent three dimensional expansion of PTFE can be achieved. The expanded mixture has many of the same beneficial properties of mechanically expanded PTFE and numerous properties previously unavailable with expanded PTFE products.

Abstract: A composite, porous, liquid-permeable article is provided which is a multilayer structure of discrete, bonded layers of porous, expanded polytetrafluoroethylene (EPTFE). The composite has its interior and exterior surfaces coated with a perfluoro ion exchange polymer to render the composite hydrophilic so as to resist gas locking in aqueous media. Initially, the diaphragm may also contain a water-soluble surfactant to assist in initial water penetration into the pores of the composite. An improved electrolytic cell is provided having the composite diaphragm as the porous separator in the electrolysis of alkali halide solutions. The diaphragm is also useful as an improved filter medium.

Abstract: A composite, porous, liquid-permeable article is provided which is a multilayer structure of discrete, bonded layers of porous, expanded polytetrafluoroethylene (EPTFE), which composite has its interior and exterior surfaces coated with a perfluoro ion exchange polymer to render the composite hydrophilic so as to resist gas locking in aqueous media wherein a composite diaphragm made therefrom, may also contain a water-soluble surfactant to assist in initial water penetration into the pores of the composite whereby an improved electrolytic cell is provided having the composite diaphragm as the porous separator in the electrolysis of alkali halide solutions and wherein the diaphragm is also useful as an improved filter medium.

Abstract: Porous polytetrafluoroethylene materials having high strength and coarse microstructure are produced by densifying the materials after removal of lubricant and then stretching. The term, "coarse," is used to indicate that the nodes are larger, the fibrils are longer, and the effective pore size is larger than conventional materials of the same matrix tensile strength. Densification can be achieved through the use of such devices as a densification die, a calender machine, or a press. This invention can be used to produce all kinds of shaped articles.

Abstract: A method for producing a multi-component, porous PTFE article. Components of PTFE containing a liquid lubricant are placed in intimate contact, dried and then stretched in one or more directions. The PTFE components may optionally contain a filler. The resultant product has a virtually uninterrupted structure at the join and possesses very high bond strengths.

Abstract: A method for producing a multi-component, porous PTFE article. Components of PTFE containing a liquid lubricant are placed in intimate contact, dried and then stretched in one or more directions. The PTFE components may optionally contain a filler. The resultant product has a virtually uninterrupted structure at the join and possesses very high bond strengths.