What are PTFE gaskets

All Seals is a recognized leading converter of high quality PTFE gaskets, seals, washers and insulators. 
All Seals has experience in the providing of precision PTFE gaskets, seals, washers, and insulators for a wide range of industries and applications.  Polytetrafluoroethylene (PTFE) is DuPont's trademark of Teflon. It is a synthetic fluoropolymer of tetrafluoroethylene consisting completely of carbon and fluorine. It is innately hydrophobic (repelling water and water containing substances) and has one of the lowest coefficients of friction against any solid. 
What are PTFE gaskets
PTFE has excellent dielectric properties and provides excellent thermal insulation with an operating temperature range of -400°F to 500°F. PTFE is the most chemically resistant plastic known and is unaffected by most corrosive liquids, vapors, and gases. PTFE is generally offered in thicknesses spanning from .002" to .250" thick and conforms to both FDA and AMS specifications, making it acceptable to both medical and food production industries. 
PTFE, Unfilled Teflon Gaskets
Virgin grade PTFE gaskets are made from 100% pure material which is used in most general applications. It is extremely soft and formable and is often used for chemical resistant seals and gaskets. It is made directly from the resin producer and has never been processed into a shape. It possesses the highest physical and electrical insulation properties and has increased resistance to creep (compression) under load. Virgin grade PTFE can be recognized by its whiter color compared to mechanical grade PTFE.
PTFE, Filled Teflon Gaskets
Filled PTFE gaskets are made from PTFE which integrates additives and fillers in order to improve the performance of the gasket. This improves the gaskets ability to wear and enhances its unique combination of chemical, physical and electrical properties. Filled Teflon is the most common type of PTFE gasket for industrial use as it exhibits improved mechanical strength compared to Virgin PTFE. Glass, carbon and fiber particles are typical fillers that are used to enhance the mechanical strength of the gasket depending on the application.
PTFE, Expanded Teflon Gaskets
Expanded PTFE gasket material is produced by expanding Virgin PTFE using a process that creates a uniform and highly fibrillated microstructure with equal tensile strength in all directions. This means that expanded Teflon possesses no structural weakness or a "grain". Since no additives are required, expanded Teflon also possesses the unique chemical resistance of Virgin Teflon. Expanded PTFE is much softer and more flexible than regular PTFE gaskets and thus conforms easily to irregular and rough surfaces. The material is easier to compress and minimizes creep and cold flow.