1.1 This International Standard specifies the principles
and procedures for evaluating the thermal endurante
properties of plastics exposed to elevated
temperature for long periods.
1.2 The term thermal endurante is used here to refer
to tests made in air, excluding any other influence
or stress applied to the test specimens. Thermal endurante
properties evaluated in different environments
and/or with different Stresses applied to the
test specimens require different test procedures.
1.3 In this International Standard, the study of the
thermal ageing of plastics is based solely on the
Change in certain properties resulting from a period
of exposure to elevated temperature. The properties
studied are always measured after the temperature
has returned to ambient.
The various properties of plastics Change at various
rates on thermal ageing. To enable comparisons to be
made of the thermal ageing of different plastics, the
criteria for judgement depend on the type of property
to be studied and its acceptable limiting value.
1.4 In the application of this Standard it is assumed
that a practically linear relationship exists between the
logarithm of the time required to Cause the predetermined
property Change and the reciprocal of the corresponding
absolute temperature (Arrhenius Law).
For the plastics tested, no transition, in particular a
first-Order transition, should occur in the temperature
range under study.
Diese Norm legt Grundsätze und Versuchsdurchführung zur Bewertung des thermischen Langzeitverhaltens von Kunststoffen bei andauernder Einwirkung von Wärme fest. Nach dieser Norm wird die Charakterisierung der Wärmealterung von Kunststoffen lediglich anhand der Änderung bestimmter Eigenschaften vorgenommen, die von der Lagerung bei erhöhter Temperatur herrührt. Die Eigenschaftswerte werden stets nach Abkühlung auf Raumtemperatur gemessen.