1、Designation: D2121 15Standard Test Methods forPolymer Content of Styrene Monomer1This standard is issued under the fixed designation D2121; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in pare
2、ntheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods cover the determination of thepolymer content of styrene monomer. It should be noted,however, that dimers and trimers are not mea
3、sured by these testmethods.1.2 Test Method A, which is based on the use of a spectro-photometer or photometer, is intended for the quantitativedetermination of the polymer content of styrene monomer inconcentrations up to 15 mg/kg. Samples containing more than15 mg/kg of polymer must be suitably dil
4、uted before measure-ment.1.3 Test Method B is a rapid visual procedure that isintended for the approximate evaluation of polymer to amaximum concentration of 1.0 mass %. Samples having apolymer content of 1.0 mass % or greater should be suitablydiluted prior to measurement.1.4 In determining the con
5、formance of the test results usingthis method to applicable specifications, results shall berounded off in accordance with the rounding-off method ofPractice E29.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This stand
6、ard 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 determine the applica-bility of regulatory limitations prior to use. For specific hazardstatement
7、s, see Section 9.2. Referenced Documents2.1 ASTM Standards:2D2827 Specification for Styrene MonomerD3437 Practice for Sampling and Handling Liquid CyclicProductsD4790 Terminology of Aromatic Hydrocarbons and RelatedChemicalsD6809 Guide for Quality Control and Quality AssuranceProcedures for Aromatic
8、 Hydrocarbons and Related Ma-terialsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 Other Document:OSHA Regulations, 29CFR paragraphs 1910.1000 and191
9、0.120033. Terminology3.1 See Terminology D4790 for definition of terms used inthis test method.TEST METHOD ADETERMINATION OF POLYMERIN STYRENE MONOMER PHOTOMETER METHOD4. Summary of Test Method4.1 This test method utilizes the fact that polymers presentin the monomers are insoluble in methanol. The
10、polymercontent of styrene monomer is determined by measurement ofthe degree of turbidity produced by the addition of drymethanol to the styrene sample.5. Significance and Use5.1 This test method can be used for determining polymerconcentrations in styrene monomer.5.2 This test method will not detect
11、 dimers and trimers.5.3 This test method can be used for plant control and forspecification analysis.6. Interferences6.1 Small changes in turbidity may occur with time. It is,therefore, important that the absorbance of calibration mixturesand samples be determined after standing the same length ofti
12、me.1These test methods are under the jurisdiction of ASTM Committee D16 onAromatic Hydrocarbons and Related Chemicals and are the direct responsibility ofSubcommittee D16.07 on Styrene, Ethylbenzene and C9 and C10 AromaticHydrocarbons.Current edition approved March 15, 2015. Published March 2015. Or
13、iginallyapproved in 1962. Last previous edition approved in 2007 as D2121 07. DOI:10.1520/D2121-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Doc
14、ument Summary page onthe ASTM website.3Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100
15、Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.2 Hexane is used for two reasons:6.2.1 To block out any color in the styrene, and6.2.2 To indicate dissolved water in the styrene.7. Apparatus7.1 Pipets, 10 and 15-mL.7.2 Bottles or Flasks, of suitable size equipped wi
16、th glassstoppers.7.3 Spectrophotometer or Photometer Cells, with 50 to150-mm light path.7.4 Spectrophotometer or Photometer, capable of absor-bance measurements in wavelength region of 420 nm andsensitive to 1 mg polymer/kg monomer.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemica
17、ls shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades may beused provided it is first ascertained th
18、at the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.8.2 Hexane, dry.8.3 Methanol, dry.8.4 Polystyrene:8.4.1 Prepare polystyrene as follows: wash 50 mLof styrenemonomer twice with equal volumes of 1 N NaOH solution andtwice with equal volu
19、mes of water. After the second waterwash, filter the styrene through two layers of rapid filteringready folded filter paper. Pour about 20 mL of this styrenemonomer into a test tube and heat in an oven at 100C for 24 hto promote polymerization. At the end of this time, remove thepolystyrene from the
20、 test tube by breaking the tube anddiscarding all glass. Grind the polymer plug to a fine powder inan agate mortar.8.4.2 Commercially available high-purity polystyrene pel-lets can be used; however, high-molecular weight polystyrene(150 000 molecular weight) should be specified.8.5 Styrene Monomer,
21、conforming to Specification D2827.8.6 Toluene, dry.9. Hazards9.1 Styrene monomer is flammable and polymerizes exo-thermically on contact with peroxides, mineral acids andaluminum chloride.9.2 Styrene monomer both in liquid and vapor state, when insufficient concentrations, acts as an irritant to the
22、 eyes andrespiratory tract.9.3 Consult current OSHA regulations, local regulations,and suppliersSafety Data Sheets for all materials used in thesetest methods.10. Sampling and Handling10.1 Sample the material in accordance with PracticeD3437.11. Calibration11.1 ApparatusPrepare and operate the spect
23、rophotom-eter or photometer in accordance with the manufacturersinstructions.11.2 Reference Standards and Blanks:11.2.1 Dissolve 0.0865 g of polystyrene in 1000 mL oftoluene measured at 25C, which is equivalent to 100 mg/kg ofpolymer in monomer. This serves as the standard for polymerin styrene.11.2
24、.2 Make standard solutions containing 1, 3, 6, 9, 12, and15 mg/kg of styrene polymer by diluting 1, 3, 6, 9, 12, and 15mL of the 100 mg/kg standard solution to 100 mL with toluenein a volumetric flask at 25C.11.3 Calibration Curves and Tables:11.3.1 Into each of a series of bottles equipped with gla
25、ssstoppers pipet 15 mL of dry methanol and 10 mL of a polymerstandard and mix thoroughly. Into another series of bottlespipet 15 mL of hexane and 10 mL of each polymer standardand mix thoroughly. Other volumes may be used, depending onthe capacity of the spectrophotometer cell as long as the 3:2prop
26、ortion is maintained.11.3.2 Allow the solutions to stand in the stoppered bottlesfor 15 min 6 1 min (Note 1). At the end of this time, pour thesolutions into the spectrophotometer cells and measure theabsorbance of each at a wavelength of 420 nm using thehexane/polymer standard as the blank (Note 2)
27、.NOTE 1Small changes in turbidity may occur with time. It is,therefore, important that the absorbance of calibration mixtures andsamples be determined after standing the same length of time.NOTE 2The hexane is used for two reasons: (1) to blank out any colorin the styrene, and (2) to indicate dissol
28、ved water in the styrene.11.3.3 Prepare a calibration curve by plotting the absor-bance against the milligrams per kilogram of polymer.12. Procedure12.1 Pipet 15 mL of hexane into a bottle equipped with aglass stopper.12.2 Into a second bottle, pipet 15 mL of dry methanol.12.3 Add 10 mL of styrene m
29、onomer to each bottle and mixthoroughly.12.4 Proceed as described in 11.3.2 using the hexanemixture as the blank.13. Calculation13.1 Read the milligrams per kilogram of polymer directlyfrom the calibration curve.NOTE 3Milligrams per kilogram can be converted to mass percent bydividing by 10 000.4Rea
30、gent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaan
31、d National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D2121 15214. Report14.1 Report the polymer content of the sample as milli-grams of polymer per kilogram of monomer to the nearestmg/kg. For results less than 1 mg/kg, report 1 mg/kg.15. Precision and Bias515.1 An ILS was
32、conducted which included ten laboratoriesanalyzing four samples three times. Practice E691 was fol-lowed for the design and analysis of the data; the details aregiven in ASTM Research Report RR:D16-1053.15.2 Repeatability:15.2.1 Results should not be suspect unless they differ bymore than shown in T
33、able 1. Results differing by less than rhave a 95 % probability of being correct.15.3 Reproducibility results submitted by two labs shouldnot be considered suspect unless they differ by more thanshown in Table 1. Results differing by less than R have a 95 %probability of being correct.15.4 Reproduci
34、bility limits are listed in Table 1.15.5 BiasSince there is no accepted reference materialsuitable for determining bias for the procedure in these testmethods, bias has not been determined.16. Quality Guidelines16.1 Laboratories shall have a quality control system inplace.16.1.1 Confirm the performa
35、nce of the test instrument ortest method by analyzing a quality control sample followingthe guidelines of standard statistical quality control practices.16.1.2 A quality control sample is a stable material isolatedfrom the production process and representative of the samplebeing analyzed.16.1.3 When
36、 QA/QC protocols are already established inthe testing facility, these protocols are acceptable when theyconfirm the validity of test results.16.1.4 When there are no QA/QC protocols established inthe testing facility, use the guidelines described in GuideD6809 or similar statistical quality control
37、 practices.TEST METHOD BVISUAL EVALUATION OFPOLYMER CONTENT OF STYRENE MONOMER17. Summary of Test Method17.1 This test method utilizes the fact that styrene polymersare insoluble in methanol. The polymer content of a sample ofstyrene monomer is evaluated by visual observation of thedegree of turbidi
38、ty produced by the addition of methanol to thesample. The order of magnitude of the polymer content ofstyrene monomer in the incremental steps 0.001, 0.01, 0.1, and1.0 mass % may readily be differentiated visually. For 0 %observe pure dry methanol.18. Apparatus18.1 Test Tube, 25 by 150-mm.18.2 Pipet
39、s, 2 and 10-mL.18.3 Daylight Fluorescent Tube, equipped with curved re-flector.19. Reagents19.1 Methanol, dry.19.2 Polystyrene, uncolored, unfilled, unlubricated (see8.4).19.3 Toluene, dry.20. Procedure20.1 Pipet 2 mL of sample into a clean, dry test tube, add 10mL of dry methanol by means of a pipe
40、t, stopper the test tubewith a cork covered with aluminum foil, and shake vigorouslyfor a few seconds.20.2 After shaking the test tube, inspect the mixture visuallyby looking through it toward a source of artificial daylight.Compare the observed turbidity of the mixture with thedescriptions of turbi
41、dity given in Table 3 or against known5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D16-1053. ContactASTM CustomerService at serviceastm.org.TABLE 1 Styrene (mg/kg)MaterialAverageAXRepeatabilityLimitrReproducibilityLimitRSampl
42、e10.4mg/kg 1.673 1.796 2.827Sample22mg/kg 2.413 1.711 3.792Sample34mg/kg 3.759 4.268 5.090Sample410mg/kg 10.143 3.254 9.037AThe average of the laboratories calculated averages.TABLE 2 % RecoveryMaterialAverageA(mg/kg)AverageRecovery(%)Sample10.4mg/kg 1.673 418.2Sample22mg/kg 2.413 120.6Sample34mg/kg
43、 3.759 94.0Sample410mg/kg 10.143 101.4AThe average of the laboratories calculated averages.TABLE 3 Relationship Between Polymer Content of StyreneMonomer and Turbidity of Mixture of Two Parts by VolumeStyrene Monomer and Ten Parts by Volume Dry MethanolPolymer Content ofStyrene Monomerby Weight, %AD
44、escription of Turbidity ofStyrene-Methanol Mixture1.0 or greater milk-white opaque liquid with heavy white precipitate0.1 milk-white opaque liquid with no evidence ofsedimentation0.01 cloudiness readily visible, but mixture still transparent0.001 faint trace of cloudiness; detectable only by compari
45、sonwith pure dry methanolNone no cloudiness discernible by comparison with pure drymethanolAIt is suggested that the analyst initially perform the test using reference mixturesdescribed in this table as a guide. An experienced analyst can estimate thepolymer content reliably without the use of refer
46、ence mixtures.D2121 153standards. If standards are desired, they may be prepared usingpolystyrene and toluene.21. Report21.1 From Table 3 select the turbidity description that mostnearly approximates that of the sample, and report the corre-sponding polymer content.22. Keywords22.1 polymer; polymer
47、content; styrene; styrene monomerSUMMARY OF CHANGESCommittee D16 has identified the location of selected changes to this standard since the last issue (D212107)that may impact the use of this standard. (Approved March 15, 2015.)(1) All references to AMS removed.(2) Section 3 Terminology added.(3) Se
48、ction 11.2 mass for stock solution corrected.(4) Section 15 new precision statements.(5) Section 16 revised to match D16 Editorial Guidelines.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of thi
49、s standard are expressly advised that determination of the validity of any such patent rights, and the riskof 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 standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration a
