From www.gasketwiki.com
A Filled PTFE gasket is made from PTFE which incorporates additives and fillers to improve the gasket performance. It is the most common type of PTFE gasket for industrial use as it exhibits greatly improved mechanical strength and lower creep characteristics compared to
virgin PTFE. Glass fiber and glass microspheres are typical fillers that are used to enhance the mechanical strength of the gasket. Glass microspheres provide more creep relaxation of the gasket which is suitable for non-metallic and low-load flanges. Being made primarily of PTFE, this type of gasket also exhibits excellent chemical resistances to most mediums, an anti-stick performance and some materials are even FDA compatible. The typical temperature threshold for these types of gaskets is 500ºF, which is the mechanical upper limit of PTFE.
