ISO 812:1991 pdf download.Physical testing of rubber
1 Scope
1.1 ISO 812:1991 pdf download specifies a method for determining the lowest temperature at which rubber materials do not exhibit brittle failure when impacted under specified conditions.
Brittleness temperatures thus determined do not necessarily relate to the lowest temperatures at which the material may be used, since brittleness will be modified by the conditions of contact and especially by the rate of impact. Data obtained by this method should therefore 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.
1.2 Two procedures are described: procedure A. in which the brittleness temperature is determined, and procedure B, in which the test piece is impacted at a specified temperature.
The latter procedure is used in the classification of rubber materials and for specification purposes.
NOTE 1 A similar test for rubber-coated fabrics is described in
ISO 4646:1989. Rubber. or plastics-coated fabrics — Low-temperature impact test.
2 Normative references
rIhe following standards contain provisions which,
through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
ISO 471:1983, Rubber — Standard temperatures, humidities and times for the conditioning and testing of test pieces.
ISO 1826:1981, Rubber, vulcanized — Time-interval between vulcanization and testing — Specification.
ISO 3383:1985, Rubber — General directions for achieving elevated or subnormal temperatures for test purposes.
ISO 466 1-1:1986, Rubber, vulcanized — Preparation of samples and test pieces — Part 1: Physical tests.
3 Definitions
For the purposes of this International Standard, the following definitions apply.
3.1 brittleness temperature
the lowest temperature of non-failure, due to low-temperature embrittlement, of the appropriate number of test pieces tested under the specified conditions
3.2 testing speed
the relative linear velocity at impact between the striking edge of the test apparatus and a clamped test piece
4 Apparatus and materials
A number of different impact testers are available commercially.’ The apparatus used shall meet the requirements specified below for certain of the components.
4.1 Test piece clamp and striking arm (see Figure 1)
4.1.1 The test piece clamp shall be rigid and designed to hold the test piece(s) as cantilever beam(s). Each individual test piece shall be held firmly and securely in the clamp without distortion.
4.1.2 The striking edge shall move relative to the test piece(s) along a path normal to the upper surface of the test piece(s) at a linear testing speed of 2,0 m/s ± 0,2 mIs at impact. The speed shall be maintained within this range for at least 6 mm of travel following the impact.ISO 812 pdf download.