1、Designation: D 7132 05Standard Test Method forDetermination of Retained Blowing Agent in ExtrudedPolystyrene Foam1This standard is issued under the fixed designation D 7132; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of retainedblowing agent in extruded polystyrene foam.1.2 This test meth
3、od 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 There is no similar or equivalent ISO standard.1.4 This standard does not purport to address all of
4、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 use.2. Summary of Test Method2.1 Polystyrene foams are made with a vari
5、ety of blowingagents such as hydrocarbons, hydrofluorocarbons, ethers, ke-tones, and other volatile organic chemicals. A fraction of theblowing agent used in the manufacture of foam is retained inthe product, some residing in the cell walls and some entrappedinside the cells. This test method is bas
6、ed on releasing theretained blowing agent by dissolving the polystyrene foam in asolvent, such as toluene, and then analyzing the solution for itscomponents by gas chromatography. An internal standard isused as a reference analyte and calibration of the gas chro-matograph (GC) with standard solution
7、s allows conversion ofthe GC response to the amount of blowing agent retained in thefoam matrix.3. Interferences3.1 The gas chromatogram may contain a signal(s) from thepolymer matrix that interferes with the signal(s) from theblowing agent components. Test calibration solutions with andwithout the
8、polymer matrix to rule out any interference. Thesecalibration solutions shall contain about the same amount ofdissolved resin as in the foam sample being analyzed.4. Apparatus4.1 Any GC equipped with a column suitable for resolvingblowing agent components can be used. For non-polar blowingagents, a
9、column such as HP-1 with 530-m thick film and30-m length can be used. For polar blowing agents, a columnsuch as HP-17 with 530-m thick film and 30-m length can beused. Typical operating parameters for the GC are:Head pressure (kPa) 50Initial oven temperature (C) 50Initial hold time (min) 3.5Temperat
10、ure program rate (C/min) 25Final temperature (C) 150Final hold time (min) 3Injector temperature (C) 250Detector temperature (C) 300Carrier gas HeCarrier gas flow rate (cm3/min) 30Injection sample size (L) 0.2NOTE 1An autosampler is not recommended as the transfer of asolution containing volatile com
11、ponents can lead to loss of the volatileanalyte.4.2 Analytical balance 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-
12、cm3gastight syringe with Chaney Adapter.4.6 1-L syringe.4.7 I-Chem Tall 200 series wide mouth 125-cm3samplebottles with caps and teflon/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.4.11 Ice water bath.4.12 We
13、ights 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 toluene with minimum purity of 99.8mol%.1This test method is under the jurisdiction of ASTM Committee D20 on
14、Plasticsand is the direct responsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved July 1, 2005. Published August 2005.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 Certified grade normal heptane wit
15、h 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 whenpreparing calibration solutions from such blowing agents.7. Sampling, Test Specimens,
16、 and Test Units7.1 Tare an I-Chem sample bottle with cap and septum. Cuta piece of foam using a sharp knife, transfer it immediately tothe sample bottle, and seal with cap and septum. Record thesample weight.NOTE 2The cutting action produces open cells and the blowing agenttrapped in these cells is
17、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 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 s
18、ample size, make some preliminarymeasurements as a function of sample size/shape until a constant value ofthe retained blowing agent is obtained.7.2 Typically, the sample weight is 1 g.7.3 Store the samples at about 4C, and analyze within aweek.NOTE 3When samples need to be shipped, use an insulated
19、 containerequipped with frozen ice packs. Shipping should be by overnight service.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-cm3volumetr
20、ic 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 g.8.2 Add about 90 cm3of toluene to another 100-cm3volume
21、tric 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 4The flask shall not cause the balance to respond beforeactually touching th
22、e 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 Fill th
23、e 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). This sol
24、ution maybe retained for eight hours.NOTE 5See 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 intoa tightly capped empty sample bottle.9.5 Place the sample bottle containing
25、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 thebottle so it will remain upright. Be sure that the water level i
26、seven 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 solutionmay be retained for eight hours.9.9 The amount of internal standard (Wi) in the calibrationsolution is Wistd/10 and the amount of blowing agent (Wst)i
27、nthe calibration solution is:Wst5W23 W3W11 W2(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:FIG. 1 Withdrawing Toluene SolutionD7132052RF 5Wi3 AstWst3 Ai(2)where:Ai= peak area of the internal standardAst=
28、 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 thesesolutions to establish a five-point calibr
29、ation 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 that the entire sample is dissolved.10
30、.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 with the shoulder of the bottle.10.
31、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(s) using the responsefactors determi
32、ned in 9.10.NOTE 6Depending 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 must be used in9.4 and the calculat
33、ion of Wiin 9.9 adjusted accordingly.11. Daily Quality Assurance11.1 Inject a sample of toluene from the container used tomake the internal standard solution. No peaks in the ISTD orblowing agent peak region should be detected. If peaks greaterthan the detection limit are observed then inject anothe
34、raliquot. If contamination peaks are still observed, switch to afresh bottle of toluene.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. Precision and Bias12.
35、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 62.5 %.Multip
36、le 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 foamANNEX(Mandatory Information)A1. VOLATILE BLOWING AGENT STANDARD PREPARATIONA1.1 Tare an emp
37、ty 30-cm3serum vial (with septa andseal).A1.2 Fill the serum vial with toluene to about 90 %capacity. Affix septa and seal. Record the weight of the tolueneto 0.1 mg (W1). Tare the balance with the vial containing thetoluene.A1.3 Open the blowing agent standard cylinder. Set thedelivery pressure to
38、70 kPa. To ensure gas purity, purge the linefor at least 30 seconds.A1.4 While the gas is flowing, insert the needle into the vialcontaining the toluene, as shown in Fig. A1.1, and 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.TABLE 1
39、 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 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 1.6
40、85standard deviation 0.023D7132053ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risko
41、f infringement 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
42、standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake yo
43、ur views 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).FIG. A1.1 Volatile Blowing Agent Standard PreparationD7132054
