NBN ISO 812:2021

This document specifies a method for determining the lowest temperature at which rubber materials
do not exhibit brittle failure or the temperature at which half of the test pieces used in a test fail when
impacted under specified conditions.
The temperatures thus determined do not necessarily relate to the lowest temperature at which the
material can be used since the brittleness will be affected by the conditions of test and especially by
the rate of impact. Data obtained by this method are, therefore, intended to be used to predict the
behaviour of rubbers at low temperatures only in applications in which the conditions of deformation
are similar to those specified in the test.
Three procedures are described:
— procedure A, in which the brittleness temperature is determined;
— procedure B, in which the brittleness temperature for 50 % failure is determined;
— procedure C, in which the test piece is impacted at a specified temperature.
Procedure C is used in the classification of rubber materials and for specification purposes.
NOTE A similar test for rubber-coated fabrics is described in ISO 4646.