ASTM D1925-70(1988)e1

Test Method for Yellowness Index of Plastics (Withdrawn 1995)

General Information

• Status: Withdrawn
• Publication Date: 31-Dec-1987
• Withdrawal Date: 09-Oct-1995
• Technical Committee: D20 - Plastics

Standards Content (Sample)

ASTM D1925 70 . 0759510 0023631 7 .
An American National Standard
~~l~ Designation: D 1925 - 70 (Reapproved 1988t
AMERICAN SOCIETY FOR TESTING ANO MATERIALS
1916 Race SI., Philadelphia, Pa. 19103
Reprinted from the Annual Book of ASTM Standards, Copyright ASTM
If not listed in the current combined index, will appear in the next edition.
Standard Test Method for
Yellowness Index of Plastics
This standard is issued under the fixed designation D 1925; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (E) indicates an editorial change since the last revision or reapproval.
' NOTE-Section 1.3 was added editorially October 1988.
l. Scope 3.1.1 yellowness-deviation in chroma from whiteness or
water-whiteness in the dominant wavelength range from 570
1.1 This test method is intended primarily for deter­
to 580 nm.
mining the degree of yellowness (or change of degree of
yellowness) under day-light illumination of homogeneous,
NoTE 2-A definition of a method of obtaining dominant wave­
nonfluorescent, nearly colorless transparent or nearly white length may be found in the literature.
translucent or opaque plastics. It is applicable to transmit­
3.1.2 yellowness index (YI)-the magnitude of yellowness
tance of transparent and translucent plastics and to reflec­
relative to magnesium oxide for CIE Source C. Yellowness
tance of opaque plastics (Note l ). It is based upon tristimulus
index is expressed as follows:
values calculated from data obtained on the Hardy-G.E.-type
YI= [100(1.28XcIE - l.06Zc E)]/YcIE
spectrophotometer,2 but other apparatus is satisfactory if 1
equivalent results are obtained.
where:
1.2 The values stated in SI units are to be regarded as the
Xc,E, Ycrn, and Zc,E = tristimulus values (Note 3) of the
standard.
specimen relative to Source C.
NOTE 3-By this test method, positive(+) yellowness index describes
NOTE 1-This test method has not been demonstrated for the
the presence and magnitude of yellowness; a specimen with a negative
determination of transmitted yellowness of plastics having a luminous
( - ) yellowness index will appear bluish.
transmittance below 25 %, and it has not been demonstrated for the
determination of reflected yellowness of translucent plastics.
3.1.3 change in yellowness index (.:lY/)-the difference
between an initial value, Y/ , and YI determined after a
1.3 This standard may involve hazardous materials. oper­
prescribed treatment of the plastic. ·
ations, and equipment. This standard does not purport to
address all of the safety problems associated with its use. It is
t!.Yl= YI- Y/
the responsibility of the user of this standard to establish
NOTE 4-By this calculation, positive (+) t!.YI indicates increased
appropriate safety and health practices and determine the
yellowness and negative (-) ::.YI indicates decreased yellowness or
applicability of regulatory limitations prior to use.
increased blueness.
4. Significance and Use
2. Referenced Documents
4.1 Yellowness index obtained by this test method corre­
2. l A.STM Standards:
lates reasonably well with the magnitude of yellowness
D 618 Methods of Conditioning Plastics and Electrical
perceived under day-light illumination.
Insulating Materials for Testing
4.2 Yellowness index of transparent and translucent plas­
E 259 Recommended Practice for Preparation of Refer­
tics is a function of thickness. Comparison should be made
ence White Reflectance Standards
only between specimens of comparable thickness.
E 308 Method for Computing the Colors of Objects by
4.3 For control work, tristimulus colorimeters are useful
Using the CIE System
so long as their inaccuracies and differences from this
primary test method are known.
4.4 This test method achieves its greatest accuracy in the
3. Terminology
determination of differences in yellowness index of sample
3.1 Definitions:
versus a control of similar material and colorant composi­
tion. Change of yellowness index determined by this test
1 method has proved useful in evaluation of degradation of
This test method is under the jurisdiction of the ASTM Committee D-20 on
Plastics and is the direct responsibility of Subcommittee D20.40 on Optical plastics under exposure to heat, light, or other environment.
Propenies.
Current edition approved Jan. 22. 1970. Published March 1970. Originally
5. Apparatus
published as D 1925 - 62T. Last previous edition 63T.
~ This spectrophotometer is described in Recommended Practice E 308. It is
5.1 Spectrophotometer, Recording,2 conforming to the
available as the Diano/Hardy Recording Spectrophotometer manufactured by the
requirements of Practice E 308. Other apparatus is satisfac-
Diano Corp . P.O. Box 346, 75 Forbes Blvd . Mansfield, MA 02048.
Annual Book of AST.\,/ Standards, Vol 08.01.
• Annual Book ofASTJ/ Standards. Vol 06.01.
Amwal Book o_(AST.\/ Standards. Vol 14.02.
Hardy. A. C . Handbook of Colorimetry, Technology Press, Cambridge, MA.
COPYRIGHT ASTM InternationalCOPYRIGHT ASTM International
Licensed by Information Handling ServicesLicensed by Information Handling Services

ASTM D1925 70 Ill 0759510 0023632 9 Ill
~filt, D 1925
amount of energy that strikes the surface at the specimen port may vary
tory if equivalent results are obtained.
from nearly 100 % of the energy transmitted to a percentage determined
by the relative areas of specimen port and sphere wall. Furthermore, the
6. Reference Standards
diffuse energy has a spectral composition such that the portion striking
6.1 Primary Standard-The primary standard for reflec­
the surface at the specimen port is yellower than that which is more
tance measurement is a layer of freshly prepared magnesium
widely diffused.
oxide prepared in accordance with Recommended Practice Norn ?-Matched magnesium carbonate blocks or matched
Vitrolite tiles are not recommended in the measurement of translucent
E 259. The primary standard for transmittance measurement
samples. Matched barium sulfate blocks with freshly scraped surfaces
is air.
have been demonstrated to give results comparable to magnesium oxide,
6.2 Instntment Standard-Because of the difficulty of
within the accuracy of this test method.
preparing a primary reflectance standard, magnesium car­
9.3 Obtain spectral directional reflectance relative to mag­
bonate, barium sulfate, or calibrated pieces of white struc­
nesium oxide. Exclude the specular component in reflec­
tural glass known as Vitrolite may be used as instrument
tance measurement. Back the test specimens with a white
standards.
standard to obtain spectral directional reflectance.
7. Test Specimen
10. Calculation
7.1 This test procedure does not cover specimen prepara­
10.1 Calculate the tristimulus values for Source C by
tion techniques.
numerical integration (see Practice E 308) from recorded
7.2 Opaque specimens shall have at least one plane
spectral data or by automatic integration during spectropho­
surface; transparent specimens shall have two surfaces that
tometer operation.
...