| 摘要 |
A seal of polytetrafluoroethylene is produced by extruding the starting material to form a profile of preferably rectangular cross-section, stretching the profile thus obtained and prepressing it (transversely to the longitudinal axis). To increase the dimensional stability and to improve further properties of the seal, the prepressed profile is sintered, that is to say subjected to a heat treatment. In the sintering there is a longitudinal shrinkage of the profile strand by approximately 50%. At the same time, the density increases by more than a factor of 2, whereas, with approximately uniform width, the height of the sealing profile increases slightly with respect to the prepressed state. The final sealing profile can be used for a wide variety of purposes. The seal has a better dimensional stability than the non-sintered seal, it remains flexible and can easily be rolled onto reels.
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