ASTM D2121-00

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
Designation:D2121–00
Standard Test Methods for
Polymer Content of Styrene Monomer and AMS
(a–Methylstyrene)
This standard is issued under the fixed designation D 2121; 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.
1. Scope E29 Practice for Using Significant Digits in Test Data to
Determine Conformance with Specifications
1.1 These test methods cover the determination of the
2.2 Other Document:
polymer content of styrene monomer andAMS (a–Methylsty-
OSHA Regulations,29 CFR, paragraphs 1910.1000 and
rene). It should be noted, however, that dimers and trimers are
1910.1200
not measured by these test methods.
1.2 Test Method A, which is based on the use of a spectro-
TEST METHOD A—DETERMINATION OF POLYMER
photometer or photometer, is intended for the quantitative
IN STYRENE MONOMER ORa–METHYLSTYRENE
determination of the polymer content of styrene monomer or
PHOTOMETER METHOD
AMS in concentrations up to 15 mg/kg. Samples containing
morethan15mg/kgofpolymermustbesuitablydilutedbefore
3. Summary of Test Method
measurement.
3.1 This test method utilizes the fact that polymers present
1.3 Test Method B is a rapid visual procedure that is
in the monomers are insoluble in methanol. The polymer
intended for the approximate evaluation of polymer to a
content of styrene monomer or AMS is determined by mea-
maximum concentration of 1.0 weight %. Samples having a
surement of the degree of turbidity produced by the addition of
polymer content of 1.0 weight % or greater should be suitably
dry methanol to the styrene or AMS sample.
diluted prior to measurement.
1.4 The following applies to all specified limits in this
4. Significance and Use
standard: for purposes of determining conformance with this
4.1 This test method can be used for determining polymer
standard, an observed value or a calculated value shall be
concentrations in styrene monomer or AMS.
rounded off “to the nearest unit” in the last right-hand digit
4.2 This test method will not detect dimers and trimers.
used in expressing the specification limit, in accordance with
4.3 This test method can be used for plant control and for
the rounding-off method of PracticeE29.
specification analysis.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 5. Interferences
responsibility of the user of this standard to establish appro-
5.1 Small changes in turbidity may occur with time. It is,
priate safety and health practices and determine the applica-
therefore,importantthattheabsorbanceofcalibrationmixtures
bility of regulatory limitations prior to use. For specific hazard
and samples be determined after standing the same length of
statements, see Section 8.
time.
5.2 Hexane is used for two reasons:
2. Referenced Documents
5.2.1 To block out any color in the styrene or AMS, and
2.1 ASTM Standards:
5.2.2 To indicate dissolved water in the styrene or AMS.
D 2827 Specification for Styrene Monomer
D 3437 Practice for Sampling and Handling Liquid Cyclic 6. Apparatus
Products
6.1 Pipets, 10 and 15-mL.
6.2 Bottles or Flasks, of suitable size equipped with glass
stoppers.
These test methods are under the jurisdiction of ASTM Committee D16 on
Aromatic Hydrocarbons and Related Chemicals and are the direct responsibility of
Subcommittee D16.07 on Styrene, Ethylbenzene, and C and C Aromatic
9 10
Hydrocarbons.
Current edition approved Feb. 22, 2002. Published August 2000. Originally Annual Book of ASTM Standards, Vol 14.02.
published as D 2121 – 62. Last previous edition D 2121 – 95. Available from Superintendent of Documents, U.S. Government Printing
Annual Book of ASTM Standards, Vol 06.04. Office, Washington, DC 20402.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
D2121–00
6.3 Spectrophotometer or Photometer Cells, with 50 to 10.2 Reference Standards and Blanks:
150-mm light path. 10.2.1 Dissolve 0.0905 g of polystyrene in 1000 mL of
6.4 Spectrophotometer or Photometer, capable of absor- toluene measured at 25°C, which is equivalent to 100 mg/kg of
bance measurements in wavelength region of 420 nm and polymer in monomer. This serves as the standard for polymer
sensitive to 1 mg polymer/kg monomer. in styrene and polymer in AMS.
10.2.2 Makestandardsolutionscontaining1,3,6,9,12,and
7. Reagents and Materials
15 mg/kg of styrene polymer by diluting 1, 3, 6, 9, 12, and 15
7.1 Purity of Reagents—Reagent grade chemicals shall be
mLof the 100 mg/kg standard solution to 100 mLwith toluene
used in all tests. Unless otherwise indicated, it is intended that
in a volumetric flask at 25°C.
all reagents shall conform to the specifications of the Commit-
10.3 Calibration Curves and Tables:
tee onAnalytical Reagents of theAmerican Chemical Society,
10.3.1 Into each of a series of bottles equipped with glass
where such specifications are available. Other grades may be
stoppers pipet 15 mLof dry methanol and 10 mLof a polymer
used provided it is first ascertained that the reagent is of
standard and mix thoroughly. Into another series of bottles
sufficiently high purity to permit its use without lessening the
pipet 15 mL of hexane and 10 mL of each polymer standard
accuracy of the determination.
andmixthoroughly.Othervolumesmaybeused,dependingon
7.2 Hexane, dry.
the capacity of the spectrophotometer cell as long as the 3:2
7.3 Methanol, dry.
proportion is maintained.
7.4 Polystyrene:
10.3.2 Allow the solutions to stand in the stoppered bottles
7.4.1 Preparepolystyreneasfollows:wash50mLofstyrene
for 15 min 6 1 min (Note 1).At the end of this time, pour the
monomer twice with equal volumes of 1 N NaOH solution and
solutions into the spectrophotometer cells and measure the
twice with equal volumes of water. After the second water
absorbance of each at a wavelength of 420 nm using the
wash, filter the styrene through two layers of rapid filtering
hexane/polymer standard as the blank (Note 2).
ready folded filter paper. Pour about 20 mL of this styrene
NOTE 1—Small changes in turbidity may occur with time. It is,
monomer into a test tube and heat in an oven at 100°C for 24
therefore, important that the absorbance of calibration mixtures and
h to promote polymerization. At the end of this time, remove
samples be determined after standing the same length of time.
the polystyrene from the test tube by b
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