1.1 本规程涵盖了适用于根据规程进行的光降解塑料氙弧暴露的具体程序和试验条件 G151页 和 G155页 . 本规程还包括试样的制备、最适合光降解塑料的试验条件以及试验结果的评估。 1.2 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1: 该实践在技术上等同于ISO 4892-2和实践 D2565 其中包括长期用于室外应用的塑料的氙弧暴露。 1.3 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 由光降解塑料制成的材料在暴露于太阳辐射、氧气、热量、水分和其他天气退化因素时会迅速退化。本规程用于评估塑料在产生模拟日光的设备中暴露时的光降解性( 1. , 2. ) 6. 控制温度和湿度。本实践中使用的暴露不是为了模拟局部天气现象引起的恶化，例如大气污染、生物攻击和盐水暴露。该装置与其他实验室风化装置之间的暴露结果不存在正相关性。 4.2 当操作条件在本规程的可接受范围内变化时，可以预期结果的变化。因此，使用本规程的所有试验结果必须附有第节中要求的特定操作条件 9 . 参考实践 G151页 有关适用于使用根据本规程获得的结果的注意事项的详细信息。 4.3 实验室暴露的结果不能直接外推以估计环境引起的绝对劣化率，因为加速因子取决于材料，并且对于每种材料和同一材料的不同配方，加速因子可能会显著不同。然而，在测试样本的同时暴露具有已知室外性能的类似材料（对照），可以比较在测试条件下相对于对照的耐久性。相对耐久性方面的评估也大大提高了不同实验室之间测试结果的一致性( 3. ). 4.4 测试结果将取决于按照惯例操作设备时的谨慎程度 G155页 . 重要因素包括线路电压的调节、不含盐或其他水沉积物、温度和湿度控制以及燃烧器和过滤器的条件和使用寿命。 注2: 指南中提供了关于可变性来源以及解决实验室加速暴露试验设计、执行和数据分析中可变性的策略的更多信息 G141页 . 4.5 在进行本实践之前，通常会参考被测试材料的规范。材料规范中涵盖的任何试样制备、调节、尺寸或测试参数，或其组合，应优先于本规程中提及的。如果没有材料规范，则默认条件适用。

1.1 This practice covers specific procedures and test conditions that are applicable for xenon arc exposure of photodegradable plastics conducted in accordance with Practices G151 and G155 . This practice also covers the preparation of test specimens, the test conditions best suited for photodegradable plastics, and the evaluation of test results. 1.2 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 1: This practice is technically equivalent to ISO 4892-2 and Practice D2565 which cover xenon arc exposures of plastics intended for long term use in outdoor applications. 1.3 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 Materials made from photodegradable plastics are intended to deteriorate rapidly when exposed to solar radiation, oxygen, heat, moisture and other degrading elements of the weather. This practice is used for evaluating the photodegradability of plastics when exposed in an apparatus that produces simulated daylight ( 1 , 2 ) 6 and controlled temperature and moisture. The exposure used in this practice is not intended to simulate the deterioration caused by localized weather phenomena such as atmospheric pollution, biological attack, and salt water exposure. There can be no positive correlation of exposure results between this and other laboratory weathering devices. 4.2 Variations in results can be expected when operating conditions are varied within the accepted limits of this practice. Therefore, all test results using this practice must be accompanied by the specific operating conditions required in Section 9 . Refer to Practice G151 for detailed information on the caveats applicable to use of results obtained in accordance with this practice. 4.3 The results of laboratory exposure cannot be directly extrapolated to estimate absolute rate of deterioration by the environment because the acceleration factor is material dependent and can be significantly different for each material and for different formulations of the same material. However, exposure of a similar material of known outdoor performance, a control, at the same time as the test specimens allows comparison of the durability relative to that of the control under the test conditions. Evaluation in terms of relative durabilities also greatly improves the agreement in test results among different laboratories ( 3 ). 4.4 Test results will depend on the care that is taken to operate the equipment in accordance with Practice G155 . Significant factors include regulation of line voltage, freedom from salt or other deposits from water, temperature and humidity control and condition and age of the burners and filters. Note 2: Additional information on sources of variability and on strategies for addressing variability in the design, execution and data analysis of laboratory accelerated exposure tests is found in Guide G141 . 4.5 Before proceeding with this practice, it is common practice to reference the specifications of the material being tested. Any test specimen preparation, conditioning, dimensions, or testing parameters, or combination thereof, covered in the material specification shall take precedence over those mentioned in this practice. If there are no material specifications, then the default conditions apply.