Expansion joint
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A expansion joint, or movement joint, is an assembly designed to hold parts together while safely absorbing temperature-induced expansion and contraction of building materials. They are commonly found between sections of buildings, bridges, sidewalks, railway tracks, piping systems, ships, and other structures.
Saw cut control joints in concrete
An expansion joint on the Cornish Main Line, England
Single sphere rubber bellows expansion joint, with flanges.
Polytetrafluoroethylene
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Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene, and has numerous applications because it is chemically inert. The commonly known brand name of PTFE-based composition is Teflon by Chemours, a spin-off from DuPont, which originally discovered the compound in 1938.
Advertisement for Zepel, the trade name used to market Teflon as a fabric treatment
PTFE thermal cover showing impact craters, from NASA's Ultra Heavy Cosmic Ray Experiment (UHCRE) on the Long Duration Exposure Facility (LDEF)
PTFE is often used to coat non-stick pans as it is hydrophobic and possesses fairly high heat resistance.