This part of ISO 75 specifies three methods with different values of constant bending stress that are used to determine the heat deformation temperature of plastics (including filled plastics and long fiber reinforced plastics where the fiber length before processing is up to 7.5 mm) and hard rubber The following can be used: Method A, with a bending stress of 1.80 MPa; Method B, with a bending stress of 0.45 MPa; Method C, with a bending stress of 8.00 MPa. The standard deflection s used to determine the heat deflection temperature corresponds to a bending elongation increase f specified in this part of ISO 75. The initial bending elongation when the test specimen is loaded at room temperature is neither specified nor measured in this part of ISO 75. The ratio of the bending elongation to the initial bending elongation depends on the elastic modulus of the tested material at room temperature. This method can therefore only be used to compare materials with similar elastic properties at room temperature. NOTE 1 The methods give better comparative precision for amorphous thermoplastics than for semi-crystalline ones. For some materials it may be necessary to temper the test specimens in order to obtain reliable results. If tempering is used, it generally results in an increase in the heat deflection temperature (see 6.6). NOTE 2 For additional information see ISO 75-1:2013, Section 1.
EN ISO 75-2:2013 Referenced Document
ISO 10724-1:1998 Plastics - Injection moulding of test specimens of thermosetting powder moulding compounds (PMCs) - Part 1: General principles and moulding of multipurpose test specimens
ISO 2818:1994 Plastics - Preparation of test specimens by machining
ISO 293:2004 Plastics - Compression moulding of test specimens of thermoplastic materials
ISO 294-1:1996 Plastics - Injection moulding of test specimens of thermoplastic materials - Part 1: General principles, and moulding of multipurpose and bar test specimens
ISO 75-1:2013 Plastics - Determination of temperature of deflection under load - Part 1: General test method
EN ISO 75-2:2013 history
2013EN ISO 75-2:2013 Plastics - Determination of temperature of deflection under load - Part 2: Plastics and ebonite
2004EN ISO 75-2:2004 Plastics - Determination of temperature of deflection under load - Part 2: Plastics and ebonite Incorporating Corrigendum April 2006; ISO 75-2:2004
1996EN ISO 75-2:1996 Plastics - Determination of Temperature of Deflection under Load - Part 2: Plastics and Ebonite (ISO 75-2 : 1993)