ASTM G178测试标准

ASTM G178 用锐截止-打开滤波器或光谱方法测定材料激活光谱（对辐照源的波长敏感性）的标准规程

ASTM G178-2016发行信息

标准号ASTM G178-2016

中文名 采用长通滤波器或光谱技术测定材料激活光谱 (对暴露源波长灵敏度) 的标准实施规程

英文名 Standard Practice for Determining the Activation Spectrum of a Material (Wavelength Sensitivity to an Exposure Source) Using the Sharp Cut-On Filter or Spectrographic Technique

发布日期2016

实施日期

废止日期无

国际标准分类号71.040.50 

发布单位US-ASTM

ASTM G178适用范围

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.

4.1The 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.

4.2The 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.

4.3The 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.

4.4Both the spectrographic and filter techniques provide activation spectra, but they differ in several respects:

4.4.1The spectrographic technique generally provides better resolution since it determines the effects of narrower spectral portions of the light source than the filter technique.

4.4.2The 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.

4.4.3In 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.

4.5The 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).

4.5.1Activation 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 hav......

1.1本规程描述了测定材料上曝光源各个光谱带的相对光化效应。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程序。一个使用锐利的紫外线/可见光透射滤光片，另一个使用摄谱仪来确定各个光谱区域造成的相对退化。

注1：其他技术可用于隔离光源各个光谱带的影响，例如，干涉滤光片。

1.3本技术适用于测定材料上太阳辐射和实验室加速试验装置的光谱效应。它们是针对紫外区域描述的，但是可以使用不同的截止滤光片和适当的光谱仪扩展到可见区域。

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、纺织品和其他材料。

1.5材料的光学和/或物理性质变化可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）。本标准的使用者有责任在使用前建立适当的安全和健康实践，并确定监管限制的适用性。

注2：没有等同于此标准的ISO标准。