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ISO 75-2 3rd Edition, April 15, 2013 Plastics - Determination of temperature of deflection under load - Part 2: Plastics and ebonite
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Availability date: 07/13/2021
Description / Abstract:
This part of ISO 75 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, Δεf, defined in this part of ISO
75. The initial flexural strain due to the loading of the specimen
at room temperature is neither specified nor measured in this part
of ISO 75. 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.
NOTE 1 The methods give better reproducibility with amorphous
plastics than with semi-crystalline ones. With some materials, it
can be necessary to anneal the test specimens to obtain reliable
results. Annealing procedures, if used, generally result in an
increase in the temperature of deflection under load.
NOTE 2 For additional information, see ISO 75-1:2013, Clause
1.