1、Designation: D4273 11Standard Test Method forPolyurethane Raw Materials: Determination of PrimaryHydroxyl Content of Polyether Polyols1This standard is issued under the fixed designation D4273; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 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.1. Scope*1.1 Carbon-13 Nuclear Magnetic ResonanceSpectroscopy (carbon-13 NMR), measures the primary hy-drox
3、yl content of ethylene oxide-propylene oxide polyethersused in preparing flexible foams. It is best suited for polyetherswith primary hydroxyl contents of 10 to 90 %.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This s
4、tandard 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.NOTE 1There is no known I
5、SO equivalent to this standard.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsE180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals3E386 Practice for Data Presentation Relating to High-Resolution Nu
6、clear Magnetic Resonance (NMR) Spectros-copyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 The terminology in this test method follows the standardterminology defined in Practice E386 and in TerminologyD883.4. Summary of Test Method4
7、.1 The resonance peaks of the primary and secondaryhydroxyl carbons of the polyethers used in flexible urethanefoams are well-resolved in high-resolution carbon-13 NMRspectra. The peak areas are measured by the spectrometersintegration system, and the relative primary hydroxyl content isdetermined f
8、rom the ratio of the primary hydroxyl area to thetotal area of the primary and secondary hydroxyl resonancepeaks.5. Significance and Use5.1 Measurements of primary hydroxyl content are usefulfor providing information regarding the relative reactivities ofpolyols.6. Interferences6.1 Any primary hydro
9、xyl propoxylate carbons present(where the methylene carbon is next to the hydroxyl group andthe methine carbon is next to the ether oxygen) are integratedwith the secondary hydroxyl carbons and are therefore notincluded in the primary hydroxyl content as measured by thismethod.7. Equipment7.1 Pulse
10、Fourier-Transform NMR (FT-NMR) Spectrom-eter, with carbon-13 capability and a carbon-13 resonancefrequency of 15 MHz (proton resonance frequency of 60 MHz)or higher. The spectrometer is to have a minimum signal-to-noise ratio of 70:1, based on the largest aromatic peak of 90 %ethylbenzene sample tha
11、t has been pulsed one time using a 90pulse.7.2 NMR Sample Tubes, with outer diameters of 5 mm ormore.8. Reagents8.1 All reagents are to be NMR-grade, deuterated solvents.8.2 Deuterated Chloroform or Deuterated Acetone, contain-ing tetramethylsilane (TMS) as an internal standard.9. Standards9.1 This
12、test method does not require standards. To evaluatethe test method, standards can be prepared by mixing insolution commercially available poly(propylene oxide) and1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.22 on C
13、ellular Materials -Plastics and Elastomers.Current edition approved April 1, 2011. Published April 2011. Originallyapproved in 1983. Last previous edition approved in 2005 as D4273 - 05. DOI:10.1520/D4273-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custome
14、r Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1*A Summary of Changes section appears at the end of this
15、standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.poly(ethylene oxide) diols. The molecular weight of thestandard would ideally be 300 or more since lower-molecular-weight polyols can contain structural configurations that aren
16、ot typical of polyethers used in flexible urethane foams.10. Preparation of Sample10.1 Mix 3 mL of polyol with 1.5 to 2 mL of deuteratedchloroform or deuterated acetone. Transfer an appropriateamount to the NMR tube.11. Instrument Preparation11.1 Prepare a decoupled carbon-13 NMR experiment, se-lect
17、ing appropriate parameters to obtain quantitative integra-tion of the peaks in the 67-60 ppm region.11.2 The settings presented here are examples that apply toa Bruker WP-80 spectrometer and a Varian AC 300 spectrom-eter. Instrument settings for other spectrometers vary. Consultthe manufacturers ope
18、rating manual.11.2.1 Typical Bruker WP-80 spectrometer parameters areas follows:Nucleus observed Carbon-13Spectral width 3000 HzPulse angle 30Data points 8KAcquisition time 1.36 sDelay between pulses 0.0 s1H decoupler Broadband11.2.2 Typical Varian AC 300 spectrometer parameters areas follows:Nucleu
19、s observed Carbon-13Spectral width 100 ppmPulse angle 90Data points 32KAcquisition time 2 sPulse delay 5 s1H decoupler on, or gated decoupling12. NMR Analysis12.1 Place the NMR tube containing the sample solutioninto the spectrometer probe. After a stable lock is obtained,optimize the field homogene
20、ity. Collect a sufficient number ofrepetitive scans for the analysis. The number required dependson the spectrometer, the molecular weight of the polyol, andthe functionality of the polyol. Some samples will requirerepetitive scanning for 30 min or less, while some will requirean hour or more. After
21、 scanning, transform the free inductiondecay (FID) to the frequency-domain spectrum. The primaryhydroxyl peaks at about 61 ppm and the secondary hydroxylpeaks at about 66 ppm are then expanded, amplified, andintegrated (the chemical shifts are based on TMS set at 0.0ppm). See Figs. 1-4 for examples
22、of spectra obtained for twodifferent polyols.13. Calculation13.1 Determine the areas of the primary and secondarypeaks from the integration curves. Calculate the mole percentprimary hydroxyl from the following equation:Primary hydroxyl, % 5ApAp 1 As3 100 (1)where:Ap = area of primary hydroxyl peaks,
23、 andAs = area of secondary hydroxyl peaks.The area of each peak type is in accordance with Fig. 1 andFig. 2.14. Report14.1 Report results to the nearest percent primary hydroxyl.FIG. 1 Primary Hydroxyl Carbon Peaks of 3500 MW Triol (52 % Primary)D4273 112FIG. 2 Secondary Hydroxyl Carbon Peaks of 350
24、0 MW Triol (52 % Primary)FIG. 3 Primary Hydroxyl Carbon Peaks of 5500 MW Triol (78 % Primary)FIG. 4 Secondary Hydroxyl Carbon Peaks of 5500 MW Triol (78 % Primary)D4273 11315. Precision and Bias415.1 Table 1 is based on a round robin conducted in 1979 inaccordance with Practice E691, involving six p
25、olyol sampleswith primary hydroxyl contents from 11 to 76 % and hydroxylnumbers from 24 to 109 (Table 2) tested by eight laboratories.For each polyol, all of the samples were prepared at one source,but the individual specimens were prepared at the laboratoriesthat tested them. Each test result was o
26、btained from oneindividual NMR run. Each laboratory obtained two test resultsfor each material on two separate days.15.2 In Table 1, for the polyols indicated and the test resultsthat are derived from testing two specimens of each polyol oneach of two separate days:15.2.1 Sr= within-laboratory stand
27、ard deviation of the av-erage: Ir= 2.83 Sr. (See 15.2.3 for application of Ir.)15.2.2 SR= between-laboratory standard deviation of theaverage: IR= 2.83 SR. (See 15.2.4 for application of IR.)15.2.3 RepeatabilityIn comparing two test results for thesame polyol, obtained by the same operator using the
28、 sameequipment on the same day, those test results are to be judgednot equivalent if they differ by more than the Irvalue for thatpolyol and condition.15.2.4 ReproducibilityIn comparing two test results forthe same polyol, obtained by different operators using differentequipment on different days, t
29、hose test results are to be judgednot equivalent if they differ by more than the IRvalue for thatpolyol and condition. (This applies between different labora-tories or between equipment within the same laboratory.)15.2.5 Any judgement in accordance with 15.2.3 and 15.2.4will have an approximate 95 %
30、 (0.95) probability of beingcorrect.15.2.6 Other polyols can yield somewhat different results.15.3 For further information on the methodology used inthis section, see Practice E691.15.4 BiasThere are no recognized standards on which tobase an estimate of bias for this test method.15.5 The precision
31、statements in 15.1-15.3 are based on a1979 interlaboratory study of six samples with primary hy-droxyl contents from 11 to 76 % described in Table 2. Oneanalyst in each of eight laboratories performed duplicatedeterminations and repeated them on a second day. PracticeE180 was used in developing thes
32、e precision estimates. TheNMR spectrometers used in this study were five VarianCFT-20s (80 MHz), two Jeol FX 60s (60 MHz), and oneBruker WP-80 (80 MHz).16. Keywords16.1 NMR; nuclear magnetic resonance spectroscopy; poly-urethane raw materials; primary hydroxyl, polyether polyolAPPENDIX(Nonmandatory
33、Information)X1. FLUORINE-19 NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY METHOD FOR DETERMINATION OF PRIMARYHYDROXYL CONTENT OF POLYETHER POLYOLSX1.1 ScopeX1.1.1 Fluorine-19 Nuclear Magnetic ResonanceSpectroscopy (fluorine-19 NMR), measures the primary hy-droxyl content in ethylene oxide-propylene oxide
34、polyethersused in flexible urethane foams. It is suitable for polyetherswith hydroxyl numbers of 24 to 300 and primary hydroxylpercentages of 2 to 98.X1.2 Summary of Test MethodX1.2.1 Hydroxyl-terminated polyethers are reacted withtrifluoroacetic anhydride, converting them quantitatively totrifluoro
35、acetate esters. High-resolution fluorine-19 NMR spec-tra of the esters have well-resolved resonance peaks for theesters of primary and secondary alcohols. Areas of these peaksare measured by the spectrometers integration system, and therelative primary hydroxyl content is calculated from the ratioof
36、 the areas of the primary hydroxyl peaks to the total area ofprimary and secondary hydroxyl peaks.X1.2.2 Mixtures of polyethers can be analyzed providednone of the trifluoroacetylation derivatives extract preferen-tially into aqueous bicarbonate solution. Extractable polyethersare polyethylene glyco
37、ls of molecular weight greater than 300.NOTE X1.1Ablend of polypropylene glycol (hydroxyl number equals60) and polyethylene glycol (hydroxyl number equals 75) had a calculatedprimary hydroxyl of 49.7 % and an observed value by the fluorine-19NMR derivatization method of 39.9 %. This example is extre
38、me since4Supporting data are available from ASTM Headquarters. Request RR:D20-1108.TABLE 113C Method, % Primary OH Content for EightLaboratories, Six PolyolsSample Mean SrSRIrIR1 11.1 0.96 1.71 2.72 4.832 39.6 1.95 1.51 5.52 4.273 75.4 0.83 1.43 2.35 4.054 71.7 2.00 3.46 5.66 9.795 52.0 2.50 3.40 7.
39、08 9.626 74.4 1.27 2.22 3.59 6.28TABLE 2 Description of Samples AnalyzedSample Composition Hydroxyl Number1 0.34 g PEG + 19.6 g PPGA612 1.89 g PEG + 18.1 g PPGA843 6.37 g PEG + 13.6 g PPGA1524 ethoxylated poly(propylene oxide) 245 ethoxylated poly(propylene oxide) 526 ethoxylated poly(propylene oxid
40、e) 74APEG refers to a polyethylene glycol of Hydroxyl Number 358. PPG is apolypropylene glycol of Hydroxyl Number 55.9.D4273 114these components are incompatible. Nevertheless, a test is described inSection 12 to determine the test methods applicability to a particularblend.X1.2.3 The hydroxyl contr
41、ibution of chain extenders inpolyethers can be determined provided that (1) their trifluoro-acetate derivatives are not volatile under the derivatizationconditions, (2) their derivatives do not extract into aqueousbicarbonate, and (3) their fluorine-19 NMR peaks are well-resolved.NOTE X1.2A test of
42、the test methods applicability to samplescontaining chain extenders is given in Section X1.9.X1.3 EquipmentX1.3.1 NMR Spectrometer, with a fluorine-19 resonancefrequency of 75 MHz or higher.NOTE X1.3There was only a small loss in precision when this testmethod was used with 56-MHz spectrometers. Alt
43、hough this test methodis written for continuous-wave instruments, Fourier-transform NMR hasbeen used with comparable precision.X1.3.2 NMR Sample Tubes, having an outside diameter of atleast 5 mm.X1.3.3 Centrifuge, bench-top type that can provide a rela-tive centrifugal force (RCF) of about 800.X1.4
44、Reagents and MaterialsX1.4.1 All reagents should be ACS certified or reagentgrade unless otherwise specified and are to be reasonably freeof paramagnetic materials (less than 100 ppm iron, for ex-ample).X1.4.2 Trifluoroacetic AnhydrideAldrich Gold Label orthe equivalent.X1.4.3 Methylene ChlorideAlco
45、hol-free.X1.4.4 Chloroform-d1-alcohol-freeDeuterated chloro-form is used because non-deuterated chloroform usually con-tains ethanol.X1.4.5 Sodium Bicarbonate SolutionPrepare a saturatedsolution by adding 10 g of sodium bicarbonate to 100 mL ofwater.X1.4.6 Anhydrous Magnesium Sulfate, or other dryin
46、gagent.X1.4.7 FluorotrichloromethaneStabilized grade.X1.5 StandardsX1.5.1 This test method does not require standards. Toevaluate this test method, standards can be prepared fromcommercially available poly(oxypropylene oxide) and poly-(ethylene oxide) of known hydroxyl numbers. Polyethyleneglycol of
47、 molecular weight less than 300 is preferred since thetrifluoroacetate derivatives of higher-molecular-weight poly-ethylene glycols may partially extract into aqueous bicarbonatesolution (see Note X1.1).X1.6 Preparation of SampleX1.6.1 Add about1gofsample, the appropriate trifluoro-acetic anhydride
48、volume as follows, and 4 mL of methylenechloride to a 4-mm vial or test tube. Mix well.Trifluoroacetic Anhydride VolumeHydroxyl Numberof PolyolVolume Anhydride,mL24 to 75 1.076 to 150 2.0151 to 225 3.0226 to 300 4.0X1.6.1.1 Heat the uncapped vial or tube on a hot plate orsteam bath in an exhaust hoo
49、d for about 10 min or until theexcess methylene chloride and trifluoroacetic anhydride haveboiled off. Cool the concentrate (about 2 mL) to ambienttemperature. Add 0.54 mL of chloroform-d1and2mLofsaturated aqueous bicarbonate solution (Note X1.4). Cap thevial or tube and shake vigorously with venting. Decant into a10-mL centrifuge tube and centrifuge at an RCF of about 800.Transfer the organic layer (bottom) to a 1-dram vial containingabout 0.3 g of drying agent. After 5 min, filter the trifluoro-acetylated polyol solution into an NMR tube.NOTE X1.4Trifluor
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