1.1本标准描述了用于选择风化标准物质（WRM）的标准以及用于确定标准物质测量特性变化的实验室内和实验室间公差的程序。本标准还描述了比较同一类型标准物质不同批次的程序。 笔记 1-可使用风化标准物质监测一致性的实验室加速试验示例为暴露试验，如实施规程G 152中所述 ，G 153 ，G 154 ，和G 155 以及参考了根据这些标准进行测试的其他标准。可使用风化标准物质监测一致性的室外暴露示例是根据规程G 7进行的 ，G 24 ，或G 90 . 标准物质也可用于监测不涉及光暴露的暴露或调节试验的一致性。 1.2风化标准物质最常用于（1）监测暴露试验中条件的一致性，（2）确定评估试验材料的时间或辐射暴露，（3）作为与同时暴露的试验材料进行比较的参考材料。由于材料对光、热和水影响的反应具有很大的可变性，因此不能使用风化标准物质对任何暴露试验的相对严重性进行分类或表征。 1.3本规程不包括控制材料，根据定义，控制材料的成分和结构与试验材料相似，并与试验材料同时暴露。 1.4本规程概述了确定标准物质的测量特性如何随暴露于规定试验条件而变化所需的实验。它包括建立可再现的测量程序，确定引起变化的光源中的临界光谱区域，以及温度和湿度等其他临界暴露应力的影响。 ====意义和用途====== 在实验室加速暴露试验中使用风化标准物质，以验证在不同时间和不同实验室使用相同暴露条件进行的试验之间的一致性。定义暴露条件一致性的规范基于标准物质在规定时间段后的特性变化。 一些风化标准物质用于定义暴露期。要求使用这些材料的规范要求暴露材料，直到达到风化标准物质的规定变化。规范通常基于单批风化标准物质的结果。当引入新批次的参考材料时，有必要进行循环研究，以比较新批次和旧批次，并为新批次的预期性能建立适当的限制。 笔记 2-SAE J1885和SAE J1960中给出了为此目的使用透明聚苯乙烯参考标准的示例。 笔记 3-一些风化标准物质（例如蓝色羊毛）也用于定义暴露时间。 尽管本标准未具体涵盖，但描述用于监测暴露一致性的标准物质特征的程序通常也适用于定义暴露期的标准物质特征。 重要的是，测试实验室加速装置中暴露的一致性，使用与测试材料响应方式类似的测试条件响应的风化标准物质。因此，风化标准物质应对主要导致试验材料降解的光源光谱区域敏感，以提供最有意义的暴露试验一致性评估。 如果温度和湿度条件是试验材料降解的重要因素，则风化标准物质还应提供有关温度和湿度条件一致性的信息。 笔记 4-材料均匀性也可能是选择风化标准物质的一个重要因素，特别是当风化是由杂质吸收的辐射引起的，例如暴露于300 nm以上辐射的脂肪族聚合物。 风化标准物质特征特性的测量可能会出现误差，具体取决于用于测量特性的仪器和程序。重要的是制定清晰的测量程序，尽量减少操作员误解的机会。 确定特征特性测量引起的可变性水平也很重要。 当使用参考材料监测或规定暴露试验的一致性时，重要的是，由参考材料变化定义的任何规范限值都应基于对适当设计的循环试验结果的良好统计分析。本规程提供了一个程序，可以按照该程序建立循环，分析结果，并确定可用于规范的标准物质特性的合理变化范围。 根据本规程获得的结果仅对该轮使用的暴露周期有效- 不能应用于不同暴露周期中使用的相同风化标准物质。 标准物质特性的变化可能会受到标准物质在曝光装置中放置的影响。这通常是由于允许曝光区域内的光强度和温度变化引起的。在允许的暴露区域内随机放置风化标准物质的复制样品，可提供暴露试验整体一致性的最佳指示。 笔记 5-在某些情况下，程序要求在暴露装置或室内的特定位置暴露风化标准物质。 以这种方式使用的参考材料的结果可能无法准确表示装置内其他位置的暴露条件。

1.1 This standard describes the criteria to be used for selection of a weathering reference material (WRM) and procedures to be used for determining within lab and between lab tolerances of changes in measured properties of a reference materials. This standard also describes a procedure for comparing different lots of the same type of a reference material. Note 1—Examples of laboratory accelerated tests in which a weathering reference material could be used to monitor consistency are exposure tests such as those described in Practices G 152 , G 153 , G 154 , and G 155 and other standards in which tests conducted according to these standards are referenced. Examples of outdoor exposures where a weathering reference material could be used to monitor consistency are those conducted according to Practices G 7 , G 24 , or G 90 . A reference material can also be used to monitor consistency of exposure or conditioning test that do not involve exposure to light. 1.2 Weathering reference materials are most often used to (1) monitor consistency of conditions in exposure tests, (2) to determine the time or radiant exposure at which test materials are evaluated, (3) as a reference material for comparing to test materials exposed at the same time. Weathering reference materials cannot be used to classify or characterize the relative severity of any exposure test because of the large variability in material responses to the effects of light, heat, and water. 1.3 This practice does not cover control materials which, by definition are selected to be of similar composition and construction to the test materials, and are exposed at the same time as test materials. 1.4 This practice provides an outline of experiments required to determine how the measured properties of the reference material change as a function of exposure to specified test conditions. It includes establishment of reproducible measurement procedures, determination of the critical spectral region in the light source causing the changes, and effects of other critical exposure stresses such as temperature and moisture. ====== Significance And Use ====== Weathering reference materials are used in laboratory accelerated exposure tests to verify consistency among tests run at different times and in different laboratories, using the same exposure conditions. Specifications defining consistency of exposure conditions are based on the property change of a reference material after a defined period of time. Some weathering reference materials are used to define periods of exposure. Specifications calling for use of these materials require the material to be exposed until a defined change in the weathering reference material is achieved. Specifications are usually based on results for a single lot of the weathering reference material. When a new lot of the reference material is introduced, round-robin studies are necessary to compare the new and old lots and to establish appropriate limits for expected performance of the new lot. Note 2—An example of the use of a clear polystyrene reference standard for this purpose is given in SAE J1885 and SAE J1960. Note 3—Some weathering reference materials (for example blue wools) are also used to define periods of exposure. Although not specifically covered by this standard, the procedures described for characterizing a reference material used to monitor consistency of exposures are also generally applicable to characterizing reference materials used to define periods of exposure. It is important to test the consistency of exposure in the laboratory accelerated device with a weathering reference material that responds to the test conditions similar to the way the test materials respond. Therefore, the weathering reference material should be sensitive to the spectral region of the light source mainly responsible for producing degradation in the test materials to provide the most meaningful evaluation of exposure test consistency. The weathering reference material should also provide information on consistency of temperature and humidity conditions if the latter are important factors in degradation of the test materials. Note 4—Material homogeneity can also be an important factor in selection of a weathering reference material, particularly if weathering is initiated by the radiation absorbed by impurities as is the case in aliphatic type polymers exposed to radiation longer than 300 nm. The measurement of the characteristic property of a weathering reference material can be subject to error depending on the instrument and the procedure used to measure the property. It is important to develop measurement procedures that are clear and which minimize chances for operator misinterpretation. It is also important to determine the level of variability caused by measurement of the characteristic property. When a reference material is used to monitor or specify the consistency of an exposure test, it is important that any specification limits defined by changes in the reference material be based on a sound statistical analysis of results from a properly designed round-robin experiment. This practice provides a procedure which can be followed to set up the round-robin, analyze results, and establish reasonable limits of change in the characteristic property of the reference material that can be used in specifications. The results obtained according to this practice are valid only for the exposure cycle used for the round-robin and cannot be applied to the same weathering reference material used in a different exposure cycle. The change in characteristic property of a reference material may be affected by the placement of the reference material in the exposure device. This is often due to variations in light intensity and temperature within the allowed exposure area. Random placement of replicate specimens of the weathering reference material through-out the allowed exposure area provides the best indication of the overall consistency of the exposure test. Note 5—In some cases, procedures require exposure of a weathering reference material at a specific location within the exposure device or chamber. Results for a reference material used in this way may not provide an accurate representation of the exposure conditions in other positions within the device.