ASTM G178

ASTM G178 用銳截止-打開濾波器或光譜方法測定材料激活光譜（對輻照源的波長敏感性）的標準規(guī)程

ASTM G178-2016發(fā)行信息

標準號ASTM G178-2016

中文名 采用長通濾波器或光譜技術(shù)測定材料激活光譜 (對暴露源波長靈敏度) 的標準實施規(guī)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

發(fā)布日期2016

實施日期

廢止日期無

國際標準分類號71.040.50 

發(fā)布單位US-ASTM

ASTM G178適用范圍

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本規(guī)程描述了測定材料上曝光源各個光譜帶的相對光化效應(yīng)。激活光譜特定于材料暴露于其中以獲得激活光譜的光源。具有不同光譜功率分布的光源將產(chǎn)生不同的激活光譜。

1.2本規(guī)程描述了確定活化譜的兩個程序。一個使用銳利的紫外線/可見光透射濾光片，另一個使用攝譜儀來確定各個光譜區(qū)域造成的相對退化。

注1：其他技術(shù)可用于隔離光源各個光譜帶的影響，例如，干涉濾光片。

1.3本技術(shù)適用于測定材料上太陽輻射和實驗室加速試驗裝置的光譜效應(yīng)。它們是針對紫外區(qū)域描述的，但是可以使用不同的截止濾光片和適當?shù)墓庾V儀擴展到可見區(qū)域。

1.4該技術(shù)適用于各種透明和不透明材料，包括塑料、油漆、油墨、紡織品和其他材料。

1.5材料的光學(xué)和/或物理性質(zhì)變化可通過各種適當?shù)姆椒ù_定。評估方法超出了本實踐的范圍。

1.6本標準并非旨在解決與其使用相關(guān)的所有安全問題（如有）。本標準的使用者有責任在使用前建立適當?shù)陌踩徒】祵嵺`，并確定監(jiān)管限制的適用性。

注2：沒有等同于此標準的ISO標準。