ISO 812:1991 pdf download – Physical testing of rubber — Part A25: Determination of low-temperature brittleness.
1 Scope 1.1 This International Standard 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 The 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 4661-1:1986, 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. 1) The apparatus used shall meet the requirements specified below for certain of the components.