Editing Gore-Tex (section)

== Properties ==
Due to the high work hardening rate of PTFE, ePTFE is significantly stronger than the unstretched material. On a microscopic level, this work hardening corresponds to the increasing crystallinity of PTFE as the fibrils untangle and orient upon the application of an external stress. ePTFE has a strikingly high ultimate tensile strength (50–800 MPa) relative to its full-density counterpart (20–30 MPa) as a result of its high crystallinity. This behavior also yields a negative [[Poisson's ratio]] due to the expansion of ePTFE along all directions, contrasting the more expected reduction in the directions perpendicular to the stress in cases with volume conservation.<ref name=":0" />

ePTFE has tunable porosity based on the processing conditions and can be made permeable to certain vapors and gases. However, it is impermeable to most liquids, including water, a property that is exploited in certain applications such as raincoats. These additional properties in combination with the inherent properties of PTFE-based materials more generally (chemical inertness, thermal stability) make ePTFE a versatile material for a range of applications.<ref name=":0" />