1.1 本规程旨在涵盖塑料材料暴露于天气的程序。 注1: 参见练习 G24集团 用于玻璃下老化。 1.2 本规程仅限于材料暴露的方法和遵循的一般程序。它适用于商业成品以及所有尺寸和形状的试样。 1.3 风化影响的评估方法将取决于试验材料的预期用途。 1.4 以国际单位制表示的数值应视为标准。 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 注2: 本标准和ISO 877.2-2009方法A在技术上等同。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 4.1 根据本规程进行的试验用于评估塑料材料暴露在室外时的稳定性。由于紫外线（UV）辐射、湿润时间、温度、污染物和其他因素的差异，塑料在室外使用中的相对耐久性可能会因暴露位置而异。 因此，不能假设单个位置的一次暴露结果将有助于确定不同位置的相对耐久性。建议在不同气候的多个位置进行暴露，代表广泛的预期使用条件。 4.1.1 由于年复一年的气候变化，单次暴露试验的结果不能用于预测材料降解的绝对速率。需要几年的重复暴露才能获得给定位置的平均测试结果。 4.2 短期暴露试验的结果可以提供相对室外性能的指示，但建议不要将其用于预测材料的绝对长期性能。不到12个月的测试结果将取决于测试开始的特定季节。

1.1 This practice is intended to cover procedures for the exposure of plastic materials to weather. Note 1: See Practice G24 for aging under glass. 1.2 This practice is limited to the method by which the material is to be exposed and the general procedure to be followed. It is intended for use with finished articles of commerce as well as with all sizes and shapes of test specimens. 1.3 Means of evaluation of the effects of weathering will depend on the intended use for the test material. 1.4 The values stated in SI units are to be regarded as the standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Note 2: This standard and ISO 877.2-2009, Method A, are technically equivalent. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 4.1 Tests conducted in accordance with this practice are used to evaluate the stability of plastic materials when they are exposed outdoors. The relative durability of plastics in outdoor use can be very different depending on the location of the exposure because of differences in ultraviolet (UV) radiation, time of wetness, temperature, pollutants, and other factors. It cannot be assumed, therefore, that results from one exposure in a single location will be useful for determining relative durability in a different location. Exposures in several locations with different climates that represent a broad range of anticipated service conditions are recommended. 4.1.1 Because of year-to-year climatological variations, results from a single exposure test cannot be used to predict the absolute rate at which a material degrades. Several years of repeat exposures are needed to get an average test result for a given location. 4.2 The results of short-term exposure tests can provide an indication of relative outdoor performance, but it is recommended they not be used to predict the absolute long-term performance of a material. The results of tests conducted for less than twelve months will depend on the particular season of the year in which they begin.