ASTM G178-09
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
- Standard No.
- ASTM G178-09
- Release Date
- 2009
- Published By
- American Society for Testing and Materials (ASTM)
- Status
- Replace By
- ASTM G178-16
- Latest
- ASTM G178-16(2023)
- Scope
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.
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.
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.
Both the spectrographic and filter techniques provide activation spectra, but they differ in several respects:
The spectrographic technique generally provides better resolution since it determines the effects of narrower spectral portions of the light source than the filter technique.
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.
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), 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.
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).
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 38212;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.
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.
Comparison of the activation spectrum of .........
ASTM G178-09 Referenced Document
- ASTM D1435 Standard Practice for Outdoor Weathering of Plastics
- ASTM D1499 Standard Practice Filtered Open-Flame Carbon-Arc Type Exposures of Plastics
- ASTM D2244 Standard Test Method for Calculation of Color Differences From Instrumentally Measured Color Coordinates
- ASTM D256 Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics
- ASTM D2565 Standard Practice for Xenon-Arc Exposure of Plastics Intended for Outdoor Applications
- ASTM D4141 Standard Practice for Conducting Black Box and Solar Concentrating Exposures of Coatings
- ASTM D4329 Standard Practice for Fluorescent UV Exposure of Plastics
- ASTM D4364 Standard Practice for Performing Outdoor Accelerated Weathering Tests of Plastics Using Concentrated Sunlight
- ASTM D4459 Standard Practice for Xenon-Arc Exposure of Plastics Intended for Indoor Applications
- ASTM D4508 Standard Test Method for Chip Impact Strength of Plastics
- ASTM D4587 Standard Practice for Fluorescent UV-Condensation Exposures of Paint and Related Coatings
- ASTM D5031 Standard Practice for Enclosed Carbon-Arc Exposure Tests of Paint and Related Coatings
- ASTM D6360 Standard Practice for Enclosed Carbon-Arc Exposures of Plastics
- ASTM D638 Standard Test Method for Tensile Properties of Plastics
- ASTM D6695 Standard Practice for Xenon-Arc Exposures of Paint and Related Coatings*， 2024-04-19 Update
- ASTM D822 Standard Practice for Filtered Open-Flame Carbon-Arc Exposures of Paint and Related Coatings
- ASTM E275 Standard Practice for Describing and Measuring Performance of Ultraviolet, Visible, and Near-Infrared Spectrophotometers
- ASTM E313 Standard Practice for Calculating Yellowness and Whiteness Indices from Instrumentally Measured Color Coordinates
- ASTM E925 Standard Practice for Monitoring the Calibration of Ultraviolet-Visible Spectrophotometers whose Spectral Slit Width does not Exceed 2 nm
- ASTM G113 Standard Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials
- ASTM G147 Standard Practice for Conditioning and Handling of Nonmetallic Materials for Natural and Artificial Weathering Tests
- ASTM G152 Standard Practice for Operating Open Flame Carbon Arc Light Apparatus for Exposure of Nonmetallic Materials*， 2024-04-19 Update
- ASTM G153 Standard Practice for Operating Enclosed Carbon Arc Light Apparatus for Exposure of Nonmetallic Materials
- ASTM G154 Standard Practice for Operating Fluorescent Ultraviolet (UV) Lamp Apparatus for Exposure of Materials
- ASTM G155 Standard Practice for Operating Xenon Arc Lamp Apparatus for Exposure of Materials*， 2024-04-19 Update
- ASTM G24 Standard Practice for Conducting Exposures to Daylight Filtered Through Glass
- ASTM G7 Standard Practice for Atmospheric Environmental Exposure Testing of Nonmetallic Materials
- ASTM G90 Standard Practice for Performing Accelerated Outdoor Weathering of Nonmetallic Materials Using Concentrated Natural Sunlight
ASTM G178-09 history
- 2023 ASTM G178-16(2023) 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
- 2016 ASTM G178-16 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
- 2009 ASTM G178-09 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
- 2003 ASTM G178-03 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
