ASTM D7132-05

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Designation: D7132 − 05
StandardTest Method for
Determination of Retained Blowing Agent in Extruded
Polystyrene Foam
This standard is issued under the fixed designation D7132; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Apparatus
1.1 This test method covers the determination of retained
4.1 Any GC equipped with a column suitable for resolving
blowing agent in extruded polystyrene foam.
blowing agent components can be used. For non-polar blowing
agents, a column such as HP-1 with 530-µm thick film and
1.2 This test method applies to organic blowing agents
30-m length can be used. For polar blowing agents, a column
which lend themselves to a convenient analysis by gas chro-
such as HP-17 with 530-µm thick film and 30-m length can be
matography. The method is not applicable to blowing agents
used. Typical operating parameters for the GC are:
such as nitrogen, carbon dioxide, or water.
Head pressure (kPa) 50
1.3 There is no similar or equivalent ISO standard.
Initial oven temperature (°C) 50
Initial hold time (min) 3.5
1.4 This standard does not purport to address all of the
Temperature program rate (°C/min) 25
safety concerns, if any, associated with its use. It is the
Final temperature (°C) 150
responsibility of the user of this standard to establish appro- Final hold time (min) 3
Injector temperature (°C) 250
priate safety and health practices and to determine the
Detector temperature (°C) 300
applicability of regulatory limitations prior to use.
Carrier gas He
Carrier gas flow rate (cm /min) 30
Injection sample size (µL) 0.2
2. Summary of Test Method
2.1 Polystyrene foams are made with a variety of blowing NOTE 1—An autosampler is not recommended as the transfer of a
solution containing volatile components can lead to loss of the volatile
agents such as hydrocarbons, hydrofluorocarbons, ethers,
analyte.
ketones, and other volatile organic chemicals.Afraction of the
blowing agent used in the manufacture of foam is retained in 4.2 Analytical balance with at least 150 g full scale and 0.1
theproduct,someresidinginthecellwallsandsomeentrapped mg resolution.
inside the cells. This test method is based on releasing the
4.3 Instrument grade air supplied at 515 6 40 kPa, helium
retained blowing agent by dissolving the polystyrene foam in a
at 450 6 40 kPa, and hydrogen at 380 6 40 kPa.
solvent, such as toluene, and then analyzing the solution for its
4.4 100-cm volumetric flasks.
components by gas chromatography. An internal standard is
3 3
used as a reference analyte and calibration of the gas chro-
4.5 1-cm syringe with Chaney Adapter, and 10-cm gas
matograph (GC) with standard solutions allows conversion of
tight syringe with Chaney Adapter.
the GC response to the amount of blowing agent retained in the
4.6 1-µL syringe.
foam matrix.
4.7 I-Chem Tall 200 series wide mouth 125-cm sample
3. Interferences
bottles with caps and teflon/silicon septa.
3.1 The gas chromatogram may contain a signal(s) from the
4.8 30-cm serum vials with crimp on teflon/silicon septa.
polymer matrix that interferes with the signal(s) from the
4.9 Rubber sleeve stoppers for volumetric flask.
blowing agent components. Test calibration solutions with and
without the polymer matrix to rule out any interference. These
4.10 Septa for GC.
calibration solutions shall contain about the same amount of
4.11 Ice water bath.
dissolved resin as in the foam sample being analyzed.
4.12 Weights to keep sample bottle submerged.
4.13 Refrigerator for sample storage.
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
and is the direct responsibility of Subcommittee D20.70 on Analytical Methods.
4.14 Insulated mailing containers with ice packs for ship-
Current edition approved July 1, 2005. Published August 2005. DOI: 10.1520/
D7132-05. ping samples.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7132 − 05
5. Reagents and Materials 9. Calibration
5.1 Certified grade toluene with minimum purity of 99.8 9.1 Tareanempty30-cm serumvial(withaseptaandseal).
mol%.
9.2 Fill the serum vial with toluene to about 90 % capacity.
Affix the septa and seal. Obtain the weight of the toluene to 0.1
5.2 Certified grade normal heptane with minimum purity of
mg (W ).
99.8 mol%.
9.3 Tare the balance with the vial containing the toluene.
5.3 Instrument grade standards for blowing agents to be
Inject1to2gofblowingagentintothevial.Weighthevialand
analyzed.
recordtheweighttothenearest0.1mg(W ).Thissolutionmay
be retained for eight hours.
6. Hazards
NOTE 5—See Annex A1 for injecting volatile or gaseous blowing
6.1 Some blowing agents are compressed liquids or gases at
agents.
room temperature. Appropriate care shall be taken when
preparing calibration solutions from such blowing agents. 9.4 Using the calibrated syringe and the technique shown in
Fig. 1, withdraw 10.0 cm of the ISTD solution and inject into
a tightly capped empty sample bottle.
7. Sampling, Test Specimens, and Test Units
9.5 Place the sample bottle containing the ISTD on the
7.1 Tare an I-Chem sample bottle with cap and septum. Cut
balance and tare the bottle.
a piece of foam using a sharp knife, transfer it immediately to
the sample bottle, and seal with cap and septum. Record the
9.6 Inject 0.2 to 1.0 cm of the solution prepared in step 9.3
sample weight.
into the tared sample bottle and record weight of the solution
added (W ).
NOTE 2—The cutting action produces open cells and the blowing agent
trapped in these cells is lost immediately. The sample size and shape shall
9.7 Place the bottle in the ice bath. Place a weight on the
be such as to minimize the ratio of area of cut surfaces to total surface
bottle so it will remain upright. Be sure that the water level is
area. The foam sample shall also be of dimensions such that it can easily
even with the shoulder of the bottle.
be placed in the sample bottle without causing any break or tear in the
sample. To establish the optimum sample size, make some preliminary
9.8 The sample shall remain in the water bath for a
measurements as a function of sample size/shape until a constant value of
minimum of one hour to equilibrate. This calibration solution
the retained blowing agent is obtained.
may be retained for eight hours.
7.2 Typically, the sample weight is 1 g.
7.3 Store the samples at about 4°C, and analyze within a
week.
NOTE 3—When samples need to be shipped, use an insulated container
equipped with frozen ice packs. Shippi
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