1.1 This International Standard specifies two methods for the determination of the temperature of deflection under load (bending stress) of plastics and ebonite:
— Method A, using a nominal surface stress of 1,80 MPa;
— Method B, using a nominal surface stress of 0,45 MPa.
1.2 The methods specified are only applicable to materials that are rigid at room temperature, and are suitable for assess-ing the behaviour of plastics and ebonite at elevated temperature under load at a specified r?te of temperature in-crease. The results obtained do not necessarily represent maximum use temperatures, because in practice essential factors such as time, loading conditions and nominal surface stress may differ from the testing conditions.
1.3 The methods are more reproducible with amorphous plastics than with semi-crystalline ones and are not recom-mended for testing laminates. With some materials, it may be necessary to anneal the test specimens to obtain reliable results.
SIS SS-ISO 75:1988 history
1988SIS SS-ISO 75:1988 Plastics and ebonite — Determination of temperature of deflection under load