Temperaturabhängigkeit des Verformungsverhaltens von PTFE‐Schälfolie. Versuche an Material mit künstlichen Fehlstellen

Abstract

When manufacturing anti-corrosion liners made from skived PTFE filiii for use in chemical cnginccring equipment, a knowledge of the force-deformation behaviour of this skived film is a necessary prerequisite for a successful operation marked by a low level of scrap. A particularly important factor is a knowledge of the effects of notch-like surface injuries to the film, such as can occur during manufacture and handling of this scratch-sensitive material. Tensile tests on specimens of PTFE skived film that had been prepared with defined pierced and cutted notches showed that in the temperature range between room temperature and 380°C surface notches have an adverse effect on tensile stress and elongation at break up to the melting point, but in particular below 100°C. Strength and deformability of notched specimens fall sharply as the tempcraturc drops to room tempcrature. A notch 0.2 mm in depth. cut in a 4 mm thick skived PTFE film, can reduce ultimate stress and elongation at break at room temperature to about half the level of an unnotched specimen. Since in the case of PTFE, a sort sintered material. the occurrence of notchlike defects can never be completely ruled out, their effect on the manufacture of anticorrosion liners made from skived film should be mitigated by increasing the processing tempcraturc. Under the application conditions that are often marked by elevated temperature and result in relatively slight film deformation, the notch problem can probably be rated as less critical that during the actual manufacture and fitting of the anticorrosion liners, when high localized stretching of the skived PTFE film often must be accepted.

Das Spannungs‐Dehnungs‐Verhalten von PTFE‐Schälfolie im Temperaturbereich zwischen +25°C und −80°C und dessen Beeinflussung durch Kerben

“…Die Bruchspannung GB der Querproben liegt wie bei hoheren Temperaturen auch unterhalb Raumtemperatur unter den Werten der Lhgsproben. Der EinfluS von Kerben an Querproben wurde nur oberhalb Raumtemperatur gepruft[3]. Es ist jedoch anzunehmen, daB…”