橡胶 硫化或热塑性 - 低温脆性的测定

[中文适用范围]： 本文件规定了确定橡胶材料不发生脆性破坏的最低温度或在规定条件下冲击时试验中使用的一半试件失效的温度的方法。 由此确定的温度不一定与材料可以使用的最低温度相关，因为脆性将受到测试条件尤其是冲击速率的影响。 因此，通过该方法获得的数据仅用于预测橡胶在低温下的行为，仅在变形条件与测试中指定的条件相似的应用中。 描述了三个程序： ——程序 A，其中确定脆性温度； ——程序B，确定50%失效时的脆性温度； ——程序C，其中试件在指定温度下受到冲击。 程序 C 用于橡胶材料的分类和规范目的。 注：ISO 4646 中描述了橡胶涂层织物的类似测试。 [外文原描述]： ISO 812:2017 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.