1.1 ISO 75 specifies methods for the determination of the temperature of deflection under load (flexural stress
under three-point loading) of plastics. Different types of test specimen and different constant loads are defined to
suit different types of material.
1.2 This part of ISO 75 gives a general test method, part 2 gives specific requirements for plastics (including
filled plastics and fibre-reinforced plastics in which the fibre length, prior to processing, is up to 7,5 mm) and
ebonite while part 3 gives specific requirements for high-strength thermosetting laminates and long-fibre-reinforced
plastics in which the fibre length is greater than 7,5 mm.
1.3 The methods specified are suitable for assessing the relative behaviour of different types of material at
elevated temperature under load at a specified rate of temperature increase. The results obtained do not
necessarily represent maximum applicable temperatures, because in practice essential factors such as time,
loading conditions and nominal surface stress may differ from the test conditions. True comparability of data can
only be achieved for materials having the same room-temperature flexural modulus.
1.4 The methods specify preferred dimensions for the test specimens. Tests which are carried out on specimens
of different dimensions, or on specimens which are prepared under different conditions, may produce different
results. Consequently, when repeatable data are required, sample preparation conditions and test variables should
be carefully controlled and recorded.
1.5 Data obtained using the test methods described may not be used to predict actual end-use performance.
The data are not intended for design analysis or predicting the endurance of materials at elevated temperatures.
1.6 For part 2, two test specimen positions are allowed. However, the flatwise position is the preferred and
recommended one, while testing in the edgewise (...abbreviated)
Diese Norm beschreibt Methoden zur Bestimmung der Wärmeformbeständigkeitstemperatur unter Last (Biegespannung und Dreipunktbelastung) für verschiedene Typen von Materialien. Dieser Teil 1 beschreibt die allgemeine Prüfmethode, Teil 2 enthält spezifische Festlegungen für Kunststoffe und Hartgummi und Teil 3 spezifische Festlegungen für hochfeste duroplastische Laminate und langfaserverstärkte Kunststoffe. Die beschriebenen Methoden sind geeignet, das Verhalten verschiedener Materialien bei erhöhter Temperatur abzuschätzen, wenn unter Belastung die Temperatur mit einer vorgegenbenen Geschwindigkeit erhöht wird. Die erhaltenen Ergebnisse stellen nicht unbedingt die maximalen Gebrauchstemperaturen dar, da sich in der Praxis wesentliche Faktoren wie Zeit, Belastungsbedingungen und Biegespannung von denen der Prüfbedingungen unterscheiden können.