DIN EN ISO 75-2:2013-08

This part of the standard specifies three methods, using different values of constant flexural stress, which can be used for the determination of the temperature of deflection under load of plastics (including filled plastics and fibre-reinforced plastics in which the fibre length, prior to processing, is up to 7,5 mm) and ebonite: - method A, using a flexural stress of 1,80 MPa; - method B, using a flexural stress of 0,45 MPa; - method C, using a flexural stress of 8,00 MPa. The standard deflection, Δs, used to determine the temperature of deflection under load corresponds to a flexural-strain increase, Δε_f, defined in this part of this standard. The initial flexural strain due to the loading of the specimen at room temperature is neither specified nor measured in this part of the standard. The ratio of this flexural-strain increase to the initial flexural strain depends on the modulus of elasticity, at room temperature, of the material under test. This method is, therefore, only suitable for comparing the temperatures of deflection of materials with similar room-temperature elastic properties. The International draft standard ISO/FDIS 75-2:2012 has been prepared by ISO/TC 61/SC 2 "Mechanical properties" (secretariat: AENOR, Spain). CEN/TC 249 "Plastics", the secretariat of which is held by NBN (Belgium), is responsible for the European Standard. On the national level, Working Committee NA 054-01-02 AA "Mechanische Eigenschaften und Probekörperherstellung" ("Mechanical properties and preparation of test specimens") of FNK is responsible for the standard.