本文件规定了在环境温度（一种方法）或高温（三种方法，A、B和C，取决于试验结束时释放试样的方式）下测定硫化橡胶和热塑性橡胶压缩永久变形特性的方法。 这些方法旨在测量硬度在10 IRHD至95 IRHD范围内的橡胶在所述一组替代条件下，在恒定应变（通常为25%）下长时间压缩后，在规定温度下保持弹性性能的能力。对于标称硬度为80 IRHD及以上的橡胶，使用较低的压缩应变: 标称硬度从80 IRHD到89 IRHD为15%，标称硬度从90 IRHD到95 IRHD为10%。 注1:当橡胶处于压缩状态时，可能会发生物理或化学变化，阻止橡胶在变形力释放后恢复到其原始尺寸。结果是一组，其大小取决于压缩的时间和温度，以及恢复的时间、温度和条件。在高温下，化学变化变得越来越重要，并导致永久变形。 注2:高温下的短时压缩永久变形试验（通常为24小时）通常用于测量固化状态、材料分类方法和确保化合物质量的规范。 在高温下进行更长时间的试验（通常为1000小时）会考虑老化的影响，通常用于预测使用性能，包括密封材料的性能。环境温度下的短时测试主要显示物理变化的影响（分子链和填料的重新定向）。

This document specifies methods for the determination of the compression set characteristics of vulcanized and thermoplastic rubbers at ambient (one method) or elevated temperatures (three methods, A, B, and C, depending on the way the test piece is released at the end of the test). The methods are intended to measure the ability of rubbers of hardness within the range 10 IRHD to 95 IRHD to retain their elastic properties at specified temperatures after prolonged compression at constant strain (normally 25 %) under one of the alternative sets of conditions described. For rubber of nominal hardness 80 IRHD and above, a lower compression strain is used: 15 % for a nominal hardness from 80 IRHD to 89 IRHD and 10 % for a nominal hardness from 90 IRHD to 95 IRHD. NOTE 1 When rubber is held under compression, physical or chemical changes that prevent the rubber returning to its original dimensions after release of the deforming force can occur. The result is a set, the magnitude of which depends on the time and temperature of compression as well as on the time, temperature, and conditions of recovery. At elevated temperatures, chemical changes become increasingly more important and lead to a permanent set. NOTE 2 Short-time compression set tests, typically for 24 h, at elevated temperatures are commonly used as a measure of the state of cure, a means of material classification, and a specification to ensure the quality of a compound. Longer tests, typically for 1 000 h, at elevated temperatures take account of the effect of ageing and are often used to predict service performance, including that of sealing materials. Short-time tests at ambient temperature show mainly the effect of physical changes (re-orientation of the molecular chains and the fillers).