ASTM D7252-2006(2011)e1 8750 Standard Test Method for Polyurethane Raw Materials Determination of Monomer and Isomers in Isocyanates《聚氨酯原材料的标准试验方法 异氰酸酯单体和同分异构体的测定》.pdf
《ASTM D7252-2006(2011)e1 8750 Standard Test Method for Polyurethane Raw Materials Determination of Monomer and Isomers in Isocyanates《聚氨酯原材料的标准试验方法 异氰酸酯单体和同分异构体的测定》.pdf》由会员分享,可在线阅读,更多相关《ASTM D7252-2006(2011)e1 8750 Standard Test Method for Polyurethane Raw Materials Determination of Monomer and Isomers in Isocyanates《聚氨酯原材料的标准试验方法 异氰酸酯单体和同分异构体的测定》.pdf(5页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D7252 06 (Reapproved 2011)1Standard Test Method forPolyurethane Raw Materials: Determination of Monomer andIsomers in Isocyanates1This standard is issued under the fixed designation D7252; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEReapproved with editorial changes in September 2011.1. Scope1.1 This test method determines th
3、e percent by weight ofmonomeric isomers and total monomer in crude or modifiedisocyanates. The test method is applicable to methylene di(phe-nylisocyanate) (MDI) and polymeric (meththylene phenyliso-cyanate) (PMDI). (See Note 1.)1.2 This standard does not purport to address all of thesafety concerns
4、, 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.NOTE 1There is no known ISO equivalent to this standard.2. Referenced Documents2.1 AST
5、M Standards:2D883 Terminology Relating to PlasticsE682 Practice for Liquid Chromatography Terms and Rela-tionshipsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 For definitions of terms used in these test methods seeTerminology D883.
6、4. Summary of Test Method4.1 The sample is reacted (derivatized) with methanol toform a mixture of methyl urethanes. The urethanes mixture isthen separated by normal phase high performance liquidchromatography (HPLC). The separated, derivatized isomersare quantified through the use of an internal st
7、andard.5. Significance and Use5.1 This test method can be used for research or for qualitycontrol to characterize isocyanates used in polyurethane prod-ucts.6. Apparatus6.1 High Performance Liquid Chromatograph, consistingof:6.1.1 Binary (or greater) solvent pump, capable of main-taining a pulse-fre
8、e flow rate of 1-3 millilitres per minute6.1.2 Sample injector, automatic or manual, capable ofreproducibly injecting a 2 microlitre volume6.1.3 Column heater, capable of maintaining a temperatureof 30 6 0.2C6.1.4 UV detector, capable of measurements at 235 nm.6.1.5 Chart recorder or Data system, ca
9、pable of peak areaintegration.6.2 HPLC analytical column, 250 mm by 4.6 mm by 5 mcyano stationary phaseNOTE 2Other chromatographic columns can be used provided it isascertained that similar chromatographic performance is obtained.6.3 Magnetic Stirring Hotplate.7. Reagents and Materials7.1 Purity of
10、ReagentsReagent-grade chemicals are to beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society, wheresuch specifications are available. Other grades can be used,provided it
11、is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.1.1 Acetanilide, 99.9 % purity, to be used as an internalstandard.7.1.2 Acetonitrile, dry. Dry this and reagents below overmolecular sieve for twenty-four hours.
12、1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.22 on Cellular Materials -Plastics and Elastomers.Current edition approved Sept. 1, 2011. Published October 2011. Originallyapproved in 2006. Last previous edition approv
13、ed in 2006 as D7252 - 06.DOI:10.1520/D7252-06R11E01.2For 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 Document Summary page onthe ASTM website.1Copyrigh
14、t ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.1.3 Ethanol, dry. Use of ethanol denatured with methanol(such as SDA-30) can be used if more readily available.7.1.4 Hexane, dry.7.1.5 Methanol, dry.7.1.6 Eluent solution, Mix 1:1 by volume of
15、 dry methanoland ethanol.7.1.7 Derivatization solution, Dissolve 0.20 g of acetanilidein 1 L of dry methanol.8. Sampling8.1 Since organic isocyanates react with atmospheric mois-ture, take special precautions in sampling. Usual samplingmethods, even when conducted rapidly, can cause contamina-tion o
16、f the sample with insoluble urea. Therefore, blanket thesample with dry air or nitrogen at all times. (WarningManydiisocyanates are known or suspected sensitizers. Over-exposure to diisocyanates can lead to adverse health effectswhich include the development of occupational asthma andother respirato
17、ry, skin and eye effects. Engineering controlsand/or personal protective equipment, including respiratory,skin and eye protection, are to be used when there is a potentialfor over-exposure to diisocyanates. The product suppliersMaterial Safety Data Sheet (MSDS) provides more detailedinformation abou
18、t potential adverse health effects and otherimportant safety and handling information. Always follow thespecific instructions provided on the MSDS.)9. Instrument Preparation9.1 The instrument settings here are to be used as a guide forlaboratory specific instrument-column combinations, which areto b
19、e adjusted to provide adequate separation and sensitivity asdescribed in Practice E682.9.1.1 PumpFlow = 1.5 mL/minEluent A (hexane) = 90 %Eluent B (1:1 by volume ethanol:methanol) = 10 %9.1.2 DetectorWavelength = 235 nmOutput Range = 2.000 au full scale9.1.3 Additional SettingsInjection volume=2LCol
20、umn Temperature = 30CStop Time = 25 minutesPost Run Time = 10 minutes9.1.4 Solvent Program9.1.4.1 After the components of interest have eluted, it isdesirable to flush the remainder of the material from thecolumn to avoid interference with subsequent analyses. Asolvent program such as the one below
21、can be used for analysisand cleanup:(1) InitialEluent A = 90 %Eluent B = 10 %Hold for 15 minutes.(2) Column FlushEluent A=0%Eluent B = 100 %Hold for 10 minutes.(3) ReequilibrationEluent A = 90 %Eluent B = 10 %Hold for 2.5 minutes10. Calibration and Standardization10.1 The primary standard consists o
22、f monomeric materialof sufficient purity and containing all isomers of interest. Theconcentrations of the isomers in the standard are to be in thesame ranges as those expected in samples to be analyzed.Because of the difficulty in obtaining primary standards for thistest, agreement on the standard m
23、aterial to be used in testingmust be obtained between the testing laboratory and therecipient of the final test results. Several strategies in obtainingsuitable standard material have been used.10.1.1 Several isomers of suitable purity are commerciallyavailable, such as those from Sigma/Aldrich (2,4
24、-MDI#51881-6; 4,4-MDI #25643-9). These individual isomers arecombined to produce a primary standard with isomers in thesame range as the samples.10.1.2 Alternatively, monomer of suitable purity consistingof unknown quantities of the isomers of interest can beanalyzed by gas chromatography with a fla
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