硫化橡胶或热塑性橡胶压缩永久变形的测定第1部分:室温或高温下

[中文适用范围]： 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，取决于测试件在试验结束时释放的方式）下测定硫化橡胶和热塑性橡胶压缩永久变形特性的方法。 考试）。 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以恒定应变（通常为 25%）长时间压缩后在指定温度下保持其弹性性能的能力。 对于标称硬度为 80 IRHD 及以上的橡胶，使用较低的压缩应变：标称硬度为 80 IRHD 至 89 IRHD 时为 15%，标称硬度为 90 IRHD 至 95 IRHD 时为 10%。 注 1：当橡胶受到压缩时，可能会发生物理或化学变化，从而阻止橡胶在释放变形力后恢复到其原始尺寸。 结果是一个集合，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：短时压缩形变测试（通常为 24 小时）在高温下通常用作固化状态的测量、材料分类的方法以及确保化合物质量的规范。 在高温下进行的较长时间测试（通常为 1000 小时）考虑了老化的影响，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取向）。 [外文原描述]： 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).