1.1 本规程描述了确定暴露源的各个光谱带对材料的相对光化效应。激活光谱特定于材料暴露于其中以获得激活光谱的光源。具有不同光谱功率分布的光源将产生不同的激活光谱。 1.2 本规程描述了确定活化谱的两个步骤。一种使用锐利的紫外线/可见光透射滤光片，另一种使用光谱仪来确定由单个光谱区域引起的相对退化。 注1: 其他技术可用于隔离光源的各个光谱带的影响，例如，干涉滤光片。 1.3 该技术适用于测定太阳辐射和实验室加速试验装置对材料的光谱效应。 它们是针对紫外线区域描述的，但可以使用不同的截止滤波器和适当的光谱仪扩展到可见光区域。 1.4 该技术适用于各种透明和不透明材料，包括塑料、油漆、油墨、纺织品和其他。 1.5 材料中的光学和/或物理性质变化可以通过各种适当的方法确定。评估方法超出了本实践的范围。 1.6 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和健康实践，并确定监管限制的适用性。 注2: 没有等同于本标准的ISO标准。 ====意义和用途====== 4.1 激活光谱识别所用特定暴露源的光谱区域，该光谱区域可能主要负责材料外观和/或物理特性的变化。 4.2 光谱学技术使用棱镜或光栅光谱仪来确定在没有其他波长的情况下，光源的孤立窄光谱带对材料的影响。 4.3 锐利切割滤光片技术使用一组专门设计的紫外线/可见光透射玻璃滤光片，以确定在同时暴露于比所需光谱带更长的波长期间光源各个光谱带的相对光化效应。 4.4 光谱和过滤技术都提供了激活光谱，但它们在几个方面有所不同: 4.4. 1. 光谱技术通常提供更好的分辨率，因为它确定了比滤光技术更窄的光源光谱部分的影响。 4.4.2 滤光技术更能代表多色辐射，样品通常暴露在不同的光化学过程中，有时是对抗性的，光化学过程往往同时发生。然而，由于滤波器仅传输比每个滤波器的截止波长长的波长，因此消除了比截止波长短的波长的对抗过程。 4.4.3 在滤波技术中，使用单独的样本来确定光谱带的影响，样本足够大，可以测量机械和光学变化。在光谱学技术中，除了冈崎型光谱仪那样大的情况外 ( 1. ) , 3. 使用单个小样本来确定所有光谱带的相对影响。因此，性能变化仅限于可以在非常小的试样截面上测量的变化。 4.5 在理论上，由引起降解的光源光谱区域上的激活光谱提供的信息适用于聚合物材料的稳定性以及稳定性测试 ( 2. ) . 4.5.1 基于不稳定材料暴露于太阳辐射的激活光谱确定了遮光要求，从而确定了用于最佳遮光保护的紫外线吸收器的类型。紫外线吸收剂的吸收光谱与材料的激活光谱越匹配，屏蔽越有效。然而，紫外线吸收剂的紫外线吸收光谱与激活光谱的良好匹配并不一定确保充分的保护，因为这不是选择有效紫外线吸收剂的唯一标准。 分散性、兼容性、迁移等因素可能对紫外线吸收剂的有效性产生重大影响（见 附注3 ). 必须使用模拟材料在使用条件下暴露的光源的光谱功率分布的光源来确定激活光谱。 注3: 在ASTM G03.01的一项研究中，基于暴露于硼硅酸盐玻璃过滤氙弧辐射的共聚酯的活化光谱预测，紫外线吸收剂a在室外使用中将优于紫外线吸收剂B，因为其对太阳模拟辐射的有害波长有更强的吸收。然而，当暴露于氙弧辐射或室外时，这两种添加剂对共聚酯的保护程度相同。 4.5.2 比较稳定材料和非稳定材料的激活光谱，可以提供有关筛选完整性的信息，并确定未充分筛选的任何光谱区域。 4.5.3 将基于太阳辐射的材料的激活光谱与基于暴露于其他类型光源的材料的激活光谱进行比较，为选择合适的人工测试源提供有用的信息。为了模拟户外暴露的影响，需要后者充分匹配太阳辐射的有害波长。自然光源和人工光源在引起降解的波长上的差异可能导致不同的降解机制和类型。 4.5.4 公布的数据表明，当暴露时间仅根据太阳紫外线辐射暴露而不是总太阳辐射暴露来确定时，不同季节条件下的自然风化试验之间可以获得更好的相关性。仅基于激活光谱确定的对材料有害的UV部分的定时曝光可以进一步改善相关性。 然而，虽然这是对目前曝光计时方式的改进，但它没有考虑湿度和温度的影响。 4.6 在较长的测试周期内，激活光谱将记录由灯具或过滤器老化或太阳辐射的日变化或季节变化引起的不同光谱功率分布的影响。 4.7 理论上，活化光谱可能随样品温度的不同而变化。然而，在环境温度（通过光谱技术）和约65°C（通过滤波技术）下，使用相同类型的辐射源获得了类似的激活光谱。

1.1 This practice describes the determination of the relative actinic effects of individual spectral bands of an exposure source on a material. The activation spectrum is specific to the light source to which the material is exposed to obtain the activation spectrum. A light source with a different spectral power distribution will produce a different activation spectrum. 1.2 This practice describes two procedures for determining an activation spectrum. One uses sharp cut-on UV/visible transmitting filters and the other uses a spectrograph to determine the relative degradation caused by individual spectral regions. Note 1: Other techniques can be used to isolate the effects of individual spectral bands of a light source, for example, interference filters. 1.3 The techniques are applicable to determination of the spectral effects of solar radiation and laboratory accelerated test devices on a material. They are described for the UV region, but can be extended into the visible region using different cut-on filters and appropriate spectrographs. 1.4 The techniques are applicable to a variety of materials, both transparent and opaque, including plastics, paints, inks, textiles and others. 1.5 The optical and/or physical property changes in a material can be determined by various appropriate methods. The methods of evaluation are beyond the scope of this practice. 1.6 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 and health practices and determine the applicability of regulatory limitations prior to use. Note 2: There is no ISO standard that is equivalent to this standard. ====== Significance And Use ====== 4.1 The activation spectrum identifies the spectral region(s) of the specific exposure source used that may be primarily responsible for changes in appearance and/or physical properties of the material. 4.2 The spectrographic technique uses a prism or grating spectrograph to determine the effect on the material of isolated narrow spectral bands of the light source, each in the absence of other wavelengths. 4.3 The sharp cut-on filter technique uses a specially designed set of sharp cut-on UV/visible transmitting glass filters to determine the relative actinic effects of individual spectral bands of the light source during simultaneous exposure to wavelengths longer than the spectral band of interest. 4.4 Both the spectrographic and filter techniques provide activation spectra, but they differ in several respects: 4.4.1 The spectrographic technique generally provides better resolution since it determines the effects of narrower spectral portions of the light source than the filter technique. 4.4.2 The filter technique is more representative of the polychromatic radiation to which samples are normally exposed with different, and sometimes antagonistic, photochemical processes often occurring simultaneously. However, since the filters only transmit wavelengths longer than the cut-on wavelength of each filter, antagonistic processes by wavelengths shorter than the cut-on are eliminated. 4.4.3 In the filter technique, separate specimens are used to determine the effect of the spectral bands and the specimens are sufficiently large for measurement of both mechanical and optical changes. In the spectrographic technique, except in the case of spectrographs as large as the Okazaki type ( 1 ) , 3 a single small specimen is used to determine the relative effects of all the spectral bands. Thus, property changes are limited to those that can be measured on very small sections of the specimen. 4.5 The information provided by activation spectra on the spectral region of the light source responsible for the degradation in theory has application to stabilization as well as to stability testing of polymeric materials ( 2 ) . 4.5.1 Activation spectra based on exposure of the unstabilized material to solar radiation identify the light screening requirements and thus the type of ultraviolet absorber to use for optimum screening protection. The closer the match of the absorption spectrum of a UV absorber to the activation spectrum of the material, the more effective the screening. However, a good match of the UV absorption spectrum of the UV absorber to the activation spectrum does not necessarily assure adequate protection since it is not the only criteria for selecting an effective UV absorber. Factors such as dispersion, compatibility, migration and others can have a significant influence on the effectiveness of a UV absorber (see Note 3 ). The activation spectrum must be determined using a light source that simulates the spectral power distribution of the one to which the material will be exposed under use conditions. Note 3: In a study by ASTM G03.01, the activation spectrum of a copolyester based on exposure to borosilicate glass-filtered xenon arc radiation predicted that UV absorber A would be superior to UV absorber B in outdoor use because of stronger absorption of the harmful wavelengths of solar simulated radiation. However, both additives protected the copolyester to the same extent when exposed either to xenon arc radiation or outdoors. 4.5.2 Comparison of the activation spectrum of the stabilized with that of the unstabilized material provides information on the completeness of screening and identifies any spectral regions that are not adequately screened. 4.5.3 Comparison of the activation spectrum of a material based on solar radiation with those based on exposure to other types of light sources provides information useful in selection of the appropriate artificial test source. An adequate match of the harmful wavelengths of solar radiation by the latter is required to simulate the effects of outdoor exposure. Differences between the natural and artificial source in the wavelengths that cause degradation can result in different mechanisms and type of degradation. 4.5.4 Published data have shown that better correlations can be obtained between natural weathering tests under different seasonal conditions when exposures are timed in terms of solar UV radiant exposure only rather than total solar radiant exposure. Timing exposures based on only the portion of the UV identified by the activation spectrum to be harmful to the material can further improve correlations. However, while it is an improvement over the way exposures are currently timed, it does not take into consideration the effect of moisture and temperature. 4.6 Over a long test period, the activation spectrum will register the effect of the different spectral power distributions caused by lamp or filter aging or daily or seasonal variation in solar radiation. 4.7 In theory, activation spectra may vary with differences in sample temperature. However, similar activation spectra have been obtained at ambient temperature (by the spectrographic technique) and at about 65°C (by the filter technique) using the same type of radiation source.