1、Designation: D7132 14Standard Test Method forDetermination of Retained Blowing Agent in ExtrudedPolystyrene Foam1This standard is issued under the fixed designation D7132; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of retainedblowing agent in extruded polystyrene foam.1.2 This test method
3、 applies to organic blowing agentswhich lend themselves to a convenient analysis by gas chro-matography. The method is not applicable to blowing agentssuch as nitrogen, carbon dioxide, or water.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are include
4、d in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and to determine theapplicability of regulatory limitations prior to
5、use.NOTE 1There is no known ISO equivalent to this standard.2. Summary of Test Method2.1 Polystyrene foams are made with a variety of blowingagents such as hydrocarbons, hydrofluorocarbons, ethers,ketones, and other volatile organic chemicals. A fraction of theblowing agent used in the manufacture o
6、f foam is retained inthe product, some residing in the cell walls and some entrappedinside the cells. This test method is based on releasing theretained blowing agent by dissolving the polystyrene foam in asolvent, such as toluene, and then analyzing the solution for itscomponents by gas chromatogra
7、phy. An internal standard isused as a reference analyte and calibration of the gas chro-matograph (GC) with standard solutions allows conversion ofthe GC response to the amount of blowing agent retained in thefoam matrix.3. Interferences3.1 The gas chromatogram has the potential to contain asignal(s
8、) from the polymer matrix that interferes with thesignal(s) from the blowing agent components. Test calibrationsolutions with and without the polymer matrix to rule out anyinterference. These calibration solutions shall contain about thesame amount of dissolved resin as in the foam sample beinganaly
9、zed.4. Apparatus4.1 Any GC equipped with a column suitable for resolvingblowing agent components is suitable for use. For example, ifseparating non-polar blowing agents, a 100 % dimethyl-polysiloxane with 530-m thick film and 30-m length is areasonable selection. If separating polar blowing agents,
10、a 50% dipheny/50 % dimethyl polysiloxane column with 530-mthick film and 30-m length is suitable. Typical operatingparameters for the GC are:Head pressure (kPa) 50Initial oven temperature (C) 50Initial hold time (min) 3.5Temperature program rate (C/min) 25Final temperature (C) 150Final hold time (mi
11、n) 3Injector temperature (C) 250Detector temperature (C) 300Carrier gas HeCarrier gas flow rate (cm3/min) 30Injection sample size (L) 0.2NOTE 2An autosampler is not recommended as the transfer of asolution containing volatile components can lead to loss of the volatileanalyte.4.2 Analytical balance
12、with at least 150 g full scale and 0.1mg resolution.4.3 Instrument grade air supplied at 515 6 40 kPa, heliumat 450 6 40 kPa, and hydrogen at 380 6 40 kPa.4.4 100-cm3volumetric flasks.4.5 1-cm3syringe with Chaney Adapter, and 10-cm3gastight syringe with Chaney Adapter.4.6 1-L syringe.4.7 Tall, wide
13、mouth 125-cm3sample bottles with caps andteflon/silicon septa.4.8 30-cm3serum vials with crimp on teflon/silicon septa.4.9 Rubber sleeve stoppers for volumetric flask.4.10 Septa for GC.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Su
14、bcommittee D20.70 on Analytical Methods.Current edition approved March 1, 2014. Published March 2014. Originallyapproved in 2005. Last previous edition approved in 2013 as D7132 13. DOI:10.1520/D7132-14.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 10
15、0 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.11 Ice water bath.4.12 Weights to keep sample bottle submerged.4.13 Refrigerator for sample storage.4.14 Insulated mailing containers with ice packs for ship-ping samples.5. Reagents and Materials5.1 Certified grade
16、toluene with minimum purity of 99.8mol%.5.2 Certified grade normal heptane with minimum purity of99.8 mol%.5.3 Instrument grade standards for blowing agents to beanalyzed.6. Hazards6.1 Some blowing agents are compressed liquids or gases atroom temperature. Appropriate care shall be taken whenprepari
17、ng calibration solutions from such blowing agents.7. Sampling, Test Specimens, and Test Units7.1 Record the manufacture date of the foam and the date ofmaterial sampling.7.2 Tare sample bottle with cap and septum. Cut a piece offoam using a sharp knife, transfer it immediately to the samplebottle, a
18、nd seal with cap and septum. Record the sampleweight.NOTE 3The cutting action produces open cells and the blowing agenttrapped in these cells is lost immediately. The sample size and shape shallbe such as to minimize the ratio of area of cut surfaces to total surfacearea. The foam sample shall also
19、be of dimensions such that it can easilybe placed in the sample bottle without causing any break or tear in thesample. To establish the optimum sample size, make some preliminarymeasurements as a function of sample size/shape until a constant value ofthe retained blowing agent is obtained.NOTE 4If t
20、esting foam board, the sample dimensions and locationsuch as surface or core should be reported.7.3 Typically, the sample weight is 1 gram.7.4 Store the samples at about 4C, and analyze within aweek.NOTE 5When samples need to be shipped, use an insulated containerequipped with frozen ice packs. Ship
21、ping should be by overnight service.7.5 Record the date of the blowing agent analysis.8. Internal Standard Preparation8.1 Affix a Chaney adapter to the 10-cm3syringe andcalibrate the syringe in accordance with steps 8.1.1 8.1.3.8.1.1 Measure and record the weight of 100 cm3of toluenein a 100-cm3volu
22、metric flask.8.1.2 Fill the 10-cm3syringe from the flask using theChaney adapter for volume control.8.1.3 Inject the toluene into a pre-weighed sample bottle.Weigh the bottle. The weight shall be110 of the weightobtained in step 8.1.1 within 0.01 gram.8.2 Add about 90 cm3of toluene to another 100-cm
23、3volumetric flask. Cap the flask with an unused rubber sleevestopper. Remove any static and dry the outside of flask with anionized air blower.8.3 Place the flask on the balance pan, allow it to stabilize,and tare the balance.NOTE 6The flask shall not cause the balance to respond beforeactually touc
24、hing the balance pan.8.4 Inject 0.2 to 0.4 cm3heptane into the flask and weigh tothe nearest 0.1 mg (Wistd).8.5 Dilute to the mark with toluene. It is acceptable to retainthis internal standard (ISTD) solution for 24 hours.9. Calibration9.1 Tare an empty 30-cm3serum vial (with a septa and seal).9.2
25、Fill the serum vial with toluene to about 90 % capacity.Affix the septa and seal. Obtain the weight of the toluene to 0.1mg (W1).9.3 Tare the balance with the vial containing the toluene.Inject 1 to 2 g of blowing agent into the vial. Weigh the vial andrecord the weight to the nearest 0.1 mg (W2). T
26、his solution isnot to be retained for more than eight hours.NOTE 7See Annex A1 for injecting volatile or gaseous blowingagents.9.4 Using the calibrated syringe and the technique shown inFig. 1, withdraw 10.0 cm3of the ISTD solution and inject intoFIG. 1 Withdrawing Toluene SolutionD7132 142a tightly
27、 capped empty sample bottle.9.5 Place the sample bottle containing the ISTD on thebalance and tare the bottle.9.6 Inject 0.2 to 1.0 cm3of the solution prepared in step 9.3into the tared sample bottle and record weight of the solutionadded (W3).9.7 Place the bottle in the ice bath. Place a weight on
28、thebottle so it will remain upright. Be sure that the water level iseven with the shoulder of the bottle.9.8 The sample shall remain in the water bath for aminimum of one hour to equilibrate. This calibration solutionis not to be retained for more than eight hours.9.9 The amount of internal standard
29、 (Wi) in the calibrationsolution is Wistd/10 and the amount of blowing agent (Wst)inthe calibration solution is:Wst5W23W3W11W2(1)9.10 Inject 0.2 L of the calibration solution into the GC andcalculate the response factor for the blowing agent using thefollowing formula:RF 5Wi3AstWst3Ai(2)where:Ai= pe
30、ak area of the internal standardAst= peak area of the blowing agent.9.11 Repeat steps 9.4 9.10 with five different injectionamounts of the solution from 9.3 (or Step 3 of Annex A1)togenerate calibration solutions bracketing the expected amountof blowing agent in about1goffoam sample. Use thesesoluti
31、ons to establish a five-point calibration curve.9.12 Repeat steps 9.1 9.11 for each blowing agent.10. Procedure10.1 Using the calibrated syringe and the technique shownin Fig. 1, withdraw 10.0 cm3of the ISTD solution, and injectinto the bottle containing the foam sample. Shake the bottle toensure th
32、at the entire sample is dissolved.10.2 If the sample weighs more than 1.3 g, add toluene (notthe ISTD solution) to reduce the concentration to about 10 %polystyrene.10.3 Place the bottle in the ice water bath. Place a weight onthe bottle so it will remain upright. Be sure that the water levelis even
33、 with the shoulder of the bottle.10.4 Allow the bottle to equilibrate in the water bath for aminimum of one hour, but not more than eight hours.10.5 Inject 0.2 L of the solution into the GC. Measure thearea of the peak(s) corresponding to each blowing agent andconvert the areas into weight fraction(
34、s) using the responsefactors determined in 9.10.NOTE 8Depending on the sensitivity of the GC detector and theaccuracy desired, dissolve the foam sample using 10 to 25 cm3of theISTD solution in 10.1. It is imperative that if an amount of the ISTDsolution other than 10 cm3is used, then the same amount
35、 must be used in9.4 and the calculation of Wiin 9.9 adjusted accordingly.11. Daily Quality Assurance11.1 Normally, no peaks in the ISTD or blowing agent peakregion will be detected, if peaks greater than the detection limitare observed, another aliquot shall be injected. If contamina-tion peaks are
36、still observed, switch to a fresh bottle of tolueneand monitor for peaks in the blowing agent region.11.2 Prepare and analyze a calibration solution according toSection 9. The result(s) must agree within 10 % of the expectedvalue or a new five-point calibration curve must be established.12. Precisio
37、n and Bias12.1 Table 1 summarizes results of ten extruded polystyrenefoam samples from the same population tested for theirisobutane content. Each sample was injected twice. The resultsreported in Table 1 are typical of the method described here.Multiple injections of the same sample shall agree to
38、62.5 %.Multiple measurements from the same sample population shallagree to 65 %. The practical limit of quantitation of thismethod is 0.05 wt%.13. Keywords13.1 blowing agent retention; gas chromatography; polysty-rene foamD7132 143ANNEX(Mandatory Information)A1. VOLATILE BLOWING AGENT STANDARD PREPA
39、RATIONA1.1 Tare an empty 30-cm3serum vial (with septa andseal).A1.2 Fill the serum vial with toluene to about 90 % capac-ity.Affix septa and seal. Record the weight of the toluene to 0.1mg (W1). Tare the balance with the vial containing the toluene.A1.3 Open the blowing agent standard cylinder. Set
40、thedelivery pressure to 70 kPa. To ensure gas purity, purge the linefor at least 30 seconds.TABLE 1 Test values and Repeatability Standard DeviationSample No. Injection 1 Injection 2 Average (wt %)1 1.703 1.700 1.7022 1.711 1.756 1.7343 1.696 1.704 1.7004 1.686 1.645 1.6665 1.687 1.669 1.6786 1.655
41、1.686 1.6717 1.673 1.711 1.6928 1.717 1.647 1.6829 1.643 1.663 1.65310 1.664 1.674 1.669average 1.685standard deviation 0.023FIG. A1.1 Volatile Blowing Agent Standard PreparationD7132 144A1.4 While the gas is flowing, insert the needle into the vialcontaining the toluene, as shown in Fig. A1.1, and
42、inject 1 to2 g of blowing agent. Weigh the vial and record weight to thenearest 0.1 mg (W2).A1.5 Proceed to 9.4.SUMMARY OF CHANGESCommittee D20 has identified the location of selected changes to this standard since the last issue (D7132 13) that may impact the use of this standard. (March 1, 2014)(1
43、) Added 7.1, 7.5, and Note 4. (2) Revised 11.1.Committee D20 has identified the location of selected changes to this standard since the last issue (D7132 05) that may impact the use of this standard. (November 1, 2013)(1) Edited standard for permissive language, removed inmandatory situations and mo
44、ved non-mandatory options tonotes.(2) Removed references to trade names in 4.1, 4.7, and 7.2(3) Updated ISO equivalency statement and moved to Note 1.(4) Revised 11.1 to: “Normally, no peaks in the ISTD orblowing agent peak region are detected. If peaks are ob-served”(5) Editorially added units of m
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46、ingement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standa
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48、ws known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D7132 145
