1、Designation: D 4273 05Standard Test Method forPolyurethane Raw Materials: Determination of PrimaryHydroxyl Content of Polyether Polyols1This standard is issued under the fixed designation D 4273; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year 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. Scope*1.1 Carbon-13 Nuclear Magnetic ResonanceSpectroscopy (carbon-13 NMR), measures the primary hy-d
3、roxyl content of ethylene oxide-propylene oxide polyethersused in preparing flexible foams. It is best suited for polyetherswith primary hydroxyl contents of 10 to 90 %.NOTE 1There is no equivalent ISO standard.1.2 This standard does not purport to address all of thesafety concerns, if any, associat
4、ed 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.2. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Relating to PlasticsE 180 Practice for Dete
5、rmining the Precision of ASTMMethods for Analysis and Testing of Industrial ChemicalsE 386 Practice for Data Presentation Relating to High-Resolution Nuclear Magnetic Resonance (NMR) Spectros-copyE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Term
6、inology3.1 Definitions: The terminology in this test method followsthe standard terminology defined in Practice E 386 and inTerminology D 883.4. Summary of Test Method4.1 The resonance peaks of the primary and secondaryhydroxyl carbons of the polyethers used in flexible urethanefoams are well-resolv
7、ed in high-resolution carbon-13 NMRspectra. The peak areas are measured by the spectrometersintegration system, and the relative primary hydroxyl content isdetermined from the ratio of the primary hydroxyl area to thetotal area of the primary and secondary hydroxyl resonancepeaks.5. Significance and
8、 Use5.1 Measurements of primary hydroxyl content are usefulfor providing information regarding the relative reactivities ofpolyols.6. Equipment6.1 Pulse Fourier-Transform NMR (FT-NMR) Spectrom-eter, with carbon-13 capability and a carbon-13 resonancefrequency of 15 MHz or higher. The spectrometer is
9、 to have aminimum signal-to-noise ratio of 70:1, based on the largestaromatic peak of 90 % ethylbenzene sample that has beenpulsed one time using a 90 pulse.6.2 NMR Sample Tubes, with outer diameters of 5 mm ormore.7. Reagents7.1 All reagents are to be NMR-grade, deuterated solvents.7.2 Deuterated C
10、hloroform or Deuterated Acetone, contain-ing tetramethylsilane (TMS) as an internal standard.8. Standards8.1 This test method does not require standards. To evaluatethe test method, standards can be prepared by mixing insolution commercially available poly(propylene oxide) andpoly(ethylene oxide) di
11、ols. The molecular weight of thestandard would ideally be 300 or more since lower-molecular-weight polyols can contain structural configurations that arenot typical of polyethers used in flexible urethane foams.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the d
12、irect responsibility of Subcommittee D20.22 on Cellular MaterialsPlastics and Elastomers.Current edition approved July 1, 2005. Published August 2005. Originallyapproved in 1983. Last previous edition approved in 1999 as D 4273 - 99.2For referenced ASTM standards, visit the ASTM website, www.astm.or
13、g, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C
14、700, West Conshohocken, PA 19428-2959, United States.9. Preparation of Sample9.1 Add 3 mL of the polyol and 1.5 to 2 mL of deuteratedchloroform or deuterated acetone to the NMR tube. Cap thetube and mix the contents thoroughly.10. Instrument Preparation10.1 The settings presented here apply to a Bru
15、ker WP-80spectrometer. Instrument settings for other spectrometers canbe different. Consult the manufacturers operating manual.10.2 Typical Bruker WP-80 spectrometer parameters are asfollows:Nucleus observed Carbon-13Spectral width 3000 HzPulse angle 30Data points 8KAcquisition time 1.36 sDelay betw
16、een pulses 0.0 s1H decoupler Broadband10.3 Typical AC 300 spectrometer parameters are as fol-lows:Nucleus observed Carbon-13Spectral width 100 ppmPulse angle 90Data points 32KAcquisition time 2 sPulse delay 5 s1H decoupler on, or gated decoupling11. NMR Analysis11.1 Place the NMR tube containing the
17、 sample solutioninto the spectrometer probe. After a stable lock is obtained,optimize the field homogeneity. 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 s
18、amples will requirerepetitive scanning for 30 min or less, while some will requirean hour or more. After 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, am
19、plified, andintegrated (the chemical shifts are based on TMS set at 0.0ppm). See Figs. 1-4 for examples of spectra obtained for twodifferent polyols.12. Calculation12.1 Determine the areas of the primary and secondarypeaks from the integration curves. Calculate the percentprimary hydroxyl from the f
20、ollowing equation:Determine theaverage areas of the primary and secondary peaks from theintegration curves. Calculate the percent primary hydroxylfrom the following equation:Primary hydroxyl, % 5ApAp 1 As3 100 (1)where:Ap = area of primary hydroxyl peaks, andAs = area of secondary hydroxyl peaks.Are
21、as of each peak type are in accordance with Fig. 1 andFig. 2.13. Report13.1 Report results to the nearest percent primary hydroxyl.FIG. 1 Primary Hydroxyl Carbon Peaks of 3500 MW Triol (52 % Primary)D4273052FIG. 2 Secondary Hydroxyl Carbon Peaks of 3500 MW Triol (52 % Primary)FIG. 3 Primary Hydroxyl
22、 Carbon Peaks of 5500 MW Triol (78 % Primary)FIG. 4 Secondary Hydroxyl Carbon Peaks of 5500 MW Triol (78 % Primary)D427305314. Precision and Bias314.1 Table 1 is based on a round robin conducted in 1979 inaccordance with Practice E 691, involving six polyol sampleswith primary hydroxyl contents from
23、 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 obtained from oneindividual NMR run. Each laborat
24、ory obtained two test resultsfor each material on two separate days.14.2 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:14.2.1 Sr= within-laboratory standard deviation of the av-erage: Ir= 2.83 Sr. (See
25、 14.2.3 for application of Ir.)14.2.2 SR= between-laboratory standard deviation of theaverage: IR= 2.83 SR. (See 14.2.4 for application of IR.)14.2.3 RepeatabilityIn comparing two test results for thesame polyol, obtained by the same operator using the sameequipment on the same day, those test resul
26、ts are to be judgednot equivalent if they differ by more than the Irvalue for thatpolyol and condition.14.2.4 ReproducibilityIn comparing two test results forthe same polyol, obtained by different operators using differentequipment on different days, those test results are to be judgednot equivalent
27、 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.)14.2.5 Any judgement in accordance with 14.2.3 and 14.2.4will have an approximate 95 % (0.95) probability of beingcorrect.14.2.6 Other
28、 polyols can yield somewhat different results.14.3 For further information on the methodology used inthis section, see Practice E 691.14.4 BiasThere are no recognized standards on which tobase an estimate of bias for this test method.14.5 The precision statements in 14.1-14.3 are based on a1979 inte
29、rlaboratory 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. PracticeE 180 was used in developing these precision estimates. TheNMR spectrometers us
30、ed in this study were five VarianCFT-20s (80 MHz), two Jeol FX 60s (60 MHz), and oneBruker WP-80 (80 Mz).15. Keywords15.1 NMR; nuclear magnetic resonance spectroscopy; poly-urethane raw materials; primary hydroxyl, polyether polyolAPPENDIX(Nonmandatory Information)X1. FLUORINE-19 NUCLEAR MAGNETIC RE
31、SONANCE 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 polyethersused in flexible urethane foams. It i
32、s 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 totrifluoroacetate esters. High-resolution fluorine-19 NMR
33、 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 the areas of the primary hydroxyl peaks to the
34、 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 glycols of molecular weight greater than 300.NOTE X1
35、.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 extreme since3Supporting data are available from AST
36、M 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 7.08 9.626 74.4 1.27 2.22 3.59 6.28TABLE 2 Descr
37、iption 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 oxide) 74APEG refers to a polyethylene glycol of H
38、ydroxyl Number 358. PPG is apolypropylene glycol of Hydroxyl Number 55.9.D4273054these components are incompatible. Nevertheless, a test is described inSection 12 to determine the test methods applicability to a particularblend.X1.2.3 The hydroxyl contribution of chain extenders inpolyethers can be
39、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 the test methods applicability to samplescontai
40、ning 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. Although this test methodis written for continuous
41、-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 Reagents and MaterialsX1.4.1 All reagents shoul
42、d 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 ChlorideAlcohol-free.X1.4.4 Chloroform-d1-alcohol-freeDeute
43、rated 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 dryingagent.X1.4.7 FluorotrichloromethaneStabilized
44、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 molecular weight less than 300 is preferred si
45、nce 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 volume as follows, and 4 mL of methylenechlorid
46、e 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 hood for about 10 min or until theexcess methylene
47、 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 centr
48、ifuge 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 X1.4Trifluoroacetate derivatives are hydrolytically unstable.The analysis must not be interrupte
49、d once water is added.X1.7 Instrument PreparationX1.7.1 The instrument settings given here are for a VarianEM-390 spectrometer. Instrument preparation may vary withthe spectrometer. For a description of a particular spectrometerand details of its operation, refer to the manufacturers oper-ating manual.X1.7.2 Typical EM-390 console settings are as follows:Lock 30 ppm (fluorotrichloromethane)Offset + 46.3 ppmSweep width 1 ppmSweep time 2 minIntegration time 1 minSpectrum amplitude 1000 to 3000Filter time constant 0.05 sRF power 0.15 mGLock gain 3 to 4Lock powe
