1、Designation: D 5670 95 (Reapproved 2009)Standard Test Method forRubberDetermination of Residual Unsaturation inHydrogenated Nitrile Rubber (HNBR) by InfraredSpectrophotometry1This standard is issued under the fixed designation D 5670; the number immediately following the designation indicates the ye
2、ar oforiginal adoption or, in the 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.1. Scope1.1 This test method covers the percentage of residualunsa
3、turation (double bonds in unhydrogenated butadiene) inhydrogenated nitrile rubber and is based on infrared examina-tion of rubber films cast from solution.1.2 This test method is applicable to all grades of hydroge-nated nitrile rubber in the raw state.1.3 This test method assumes that specimens and
4、 infraredspectra are prepared and analyzed by experienced personneland that the equipment is operated according to the manufac-turers direction for optimum performance. No details foroperation of infrared spectrophotometers are included in thistest method.1.4 Since it is customary in infrared spectr
5、ophotometry touse wavenumbers (cm1) rather than Hertz (Hz), the unit forfrequency in the SI system, the former is employed throughoutthis test method.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 standard does not
6、 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.2. Referenced Documents2.1 ASTM Standards
7、:2D 4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustriesE 932 Practice for Describing and Measuring Performanceof Dispersive Infrared SpectrometersE 1421 Practice for Describing and Measuring Performanceof Fourier Transform Mid-Infrar
8、ed (FT-MIR) Spectrom-eters: Level Zero and Level One Tests3. Summary of Test Method3.1 Aspecimen of the raw rubber is purified by precipitationwith methanol from a solution in methyl ethyl ketone or byextraction of the solid rubber with methanol in a Soxhletapparatus.3.2 The purified rubber specimen
9、 is again dissolved inmethyl ethyl ketone and a film is cast on a potassium bromide(KBr) disc.3.3 The infrared spectrum of the film is obtained with aFourier Transform Infrared Spectrophotometer (FT-IR) or adispersive infrared spectrophotometer.3.4 The corrected absorbance of the specific absorption
10、bands for acrylonitrile (ACN), butadiene (BD), and hydroge-nated butadiene (HBD) are determined using the baselinemethod and the percentage of residual unsaturation (doublebonds in unhydrogenated butadiene) is calculated with the aidof absorbance factors from the referenced literature.34. Significan
11、ce and Use4.1 Hydrogenated nitrile rubbers are available at differentlevels of unsaturation and different acrylonitrile content.Highly saturated grades offer optimum resistance to aging,such as exposure to heat, ozone, and chemicals, and can beeffectively cured only with peroxides or high energy rad
12、iation.4.2 Partially unsaturated grades can be cured by sulfursystems in addition to peroxides and high energy radiation.4.3 This test method provides an infrared technique todetermine the unsaturation level of hydrogenated nitrile rub-bers in the raw state. It can be used for research anddevelopmen
13、t, quality control, and referee purposes.5. Apparatus5.1 Preparation of Rubber Solution:1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.11 on Chemical Analysis.Current edition approved July 1, 2009. Published September 2
14、009. Originallyapproved in 1995. Last previous edition approved in 2004 as D 5670 95 (2004)1.2For 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
15、Summary page onthe ASTM website.3Brck, D., Kautschuk, Gummi, Kunststoffe, Vol 42, 1989, pp. 107110 and194197.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.1.1 Erlenmeyer Flask with Ground Glass Stopper, (50cm3).5.1.2 Flask Shaker
16、.5.2 Precipitation of Rubber from Solution:5.2.1 Beaker, (250 cm3).5.2.2 Magnetic Stirrer.5.2.3 Dropping Funnel, (150 cm3).5.3 Extraction of Rubber:5.3.1 Soxhlet Extraction Apparatus with Flask, (150 cm3).5.3.2 Extraction Thimbles, (27 by 100 mm).5.4 Kofler Heating Bench or Other Heating Device, wit
17、htemperature control.5.5 Spectrophotometer, required resolution capability of 2cm1. The instrument must be in good operating condition asdefined by the manufacturer and Practices E 932 and E 1421.The instrument shall be capable of scale expansion along theabsorbance or transmittance axis. The spectr
18、al region of2500600 cm1is used in this test method.6. Reagents6.1 Reagent grade chemicals shall be used in all tests. Allreagents shall conform to the specification of the Committee onAnalytical Reagents of theAmerican Chemical Society.4Othergrades may be used, provided they are of sufficiently high
19、purity as not to lessen the accuracy of the determination.6.2 Methyl Ethyl Ketone.6.3 Methanol.6.4 Dry Compressed Nitrogen, (in cylinders or provided asa laboratory service).6.5 Potassium Bromide (KBr) Discs.7. Procedure7.1 Specimen Preparation:7.1.1 Specimen Purification by Precipitation (see Note
20、1):7.1.1.1 Weigh 1.0 g of the finely divided rubber specimenand dissolve in 20 cm3methyl ethyl ketone using a 50-cm3Erlenmeyer flask with ground glass stopper on a flask shaker.7.1.1.2 Transfer the solution into a 250-cm3beaker andprecipitate the rubber by slowly dropping 150 cm3methanolfrom a dropp
21、ing funnel into the solution under agitation with amagnetic stirrer.7.1.1.3 Decant the solvent, wash the precipitated rubberwith 50 cm3methanol and redissolve in 20 cm3methyl ethylketone.7.1.2 Specimen Purification by Extraction (see Note 1):7.1.2.1 Extraction is an alternative to the precipitationm
22、ethod.7.1.2.2 Weigh 1.0 g of the finely divided rubber specimeninto an extraction thimble and extract for6hinaSoxhletapparatus (150-cm3flask) with 120 cm3methanol.7.1.2.3 Remove the extracted rubber sample from thethimble and dissolve in 20 cm3methyl ethyl ketone asdescribed in 7.1.1.1.7.1.3 Prepara
23、tion of Cast Rubber Films:7.1.3.1 Cast a smooth rubber film from the solution inmethyl ethyl ketone onto a potassium bromide (KBr) disc.7.1.3.2 Evaporate the solvent on a Kofler bench or similarheating device at a maximum temperature of 100C under astream of nitrogen.7.1.3.3 The thickness of the rub
24、ber film must be chosen sothat the strongest band to be evaluated from the infraredspectrum has an absorbance of less than 0.8.7.2 Infrared Spectrum:7.2.1 Obtain a 50-scan spectrum with an FT-IR instrumentwith 2 cm1resolution or with a dispersive infrared spectro-photometer and appropriate scan para
25、meters.7.2.2 In case the repeatability and standard deviation of theabsorbance must be determined, test up to six different films ofthe same specimen.7.2.3 If only a transmittance mode operation is possiblewith the instrument being used, the spectrum shall be scannedin that mode.7.3 Calculation of R
26、esults:7.3.1 Calculate the corrected absorbance A (i) by subtractingthe baseline absorbance from the peak absorbance at the pointbelow the peak (see Fig. X1.1).7.3.2 When the transmittance mode is used, calculate thecorrected absorbance A (i) by taking the log10 of the quotientof percent transmittan
27、ce of the baseline at the point above thepeak and the percent transmittance of the peak (see Fig. X1.2).7.3.3 Draw baselines to approximately the following wave-numbers (all values are in cm1):ACN: 22802200 for the peak 2236 (see Note 2)BD: 1010910 for the peak 970HBD: 840670 for the peak 7237.3.4 I
28、f repeatability and standard deviation s (i) must bedetermined, use the normalized absorbance ratiosA970! 5 A970!/A2236!, and (1)A723! 5 A723!/A2236! (2)from spectra of different films produced from each specimen(see Note 2).7.3.5 Calculate the molar concentrations c (i) using absor-bance factors fr
29、om the referenced literature3and the measurednormalized absorbance ratios A(970) and A(723) (see Eq 1and Eq 2).7.3.6 The absorbance factors from the referenced literature3are given below:k2236! 5 1; k970! 5 2.3 6 0.03; k723! 5 0.255 6 0.002 (3)7.3.7 Calculate the molar concentrations according to th
30、efollowing equations:cACN! 51(iAi!(4)cBD! 5A970!k970!31( Ai!(5)4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals,
31、BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D 5670 95 (2009)2cHBD! 5A723!k723!31( Ai!(6)where( Ai! 5 1 1A970!k970!1A723!k723!(7)7.3.8 Calculate the percent unsaturation (double bonds inunhydrogenate
32、d butadiene) according to:% Unsaturation 5cBD!cBD! 1 cHBD!3 100 (8)7.3.9 An example of the infrared spectrum interpretationand calculation is given inTable X1.1 and Figs. X1.1 and X1.2.8. Limitation8.1 This test method is valid when the absorbance factorsfor the absorption bands at wavenumbers 2236
33、and 2214 cm1in the spectra of some grades of hydrogenated nitrile rubber areequal. When they are not equal, c (ACN) calculated only fromA (2236) will be too small and c (BD), c (HBD), and percentunsaturation will be too large.9. Report9.1 Report the following information:9.1.1 Proper specimen identi
34、fication,9.1.2 Number of data points used to obtain the result,9.1.3 The residual unsaturation of the HNBR specimen(s)reported to the nearest 0.1 percentage point, and9.1.4 Identification of any deviation from the specifiedstandard method.10. Precision and Bias510.1 This precision and bias section h
35、as been prepared inaccordance with Practice D 4483. Refer to Practice D 4483 forterminology and other statistical calculation details.10.2 The precision results in this precision and bias sectiongive an estimate of the precision of this test method with thematerials (rubbers) used in the particular
36、interlaboratory pro-gram as described below. The precision parameters should notbe used for acceptance/rejection testing of any group ofmaterials without documentation that they are applicable tothose particular materials and the specific testing protocols thatinclude these test methods.10.3 A Type
37、1 interlaboratory test program was conductedto evaluate precision. Both repeatability and reproducibility areshort term; a period of a few days separates test results. Eachdetermination (measurement) is a test result.10.4 Three different materials, (grades of HNBR), withdifferent degrees of unsatura
38、tion were used for the interlabo-ratory program. These were tested in seven laboratories on twodifferent days one week apart. On each test day duplicate testvalues were obtained. The analysis for precision followed thegeneral procedure as set forth inAnnexA5 of Practice D 4483.Each cell of the Pract
39、ice D 4483 Table 1 basic data formatcontained four values (two test days, two test results each day).The estimates for the repeatability parameters therefore containtwo undifferentiated sources of variation: replicates withindays and between days. The final precision parameters aregiven in Table 1 o
40、f this test method.10.5 The precision of this test method may be expressed inthe format of the following statements that use what is calledan “appropriate value” of r, R, (r), or (R), that is, that valueobtained from Table 1 to be used in decisions about test resultsof this test method.10.6 Repeatab
41、ilityThe repeatability, r, of this test methodhas been established as the appropriate value for any parameteras tabulated in Table 1. Two single test results obtained in thesame laboratory, under normal test method procedures, thatdiffer by more than this tabulated r must be considered asderived fro
42、m different or nonidentical sample populations.10.7 ReproducibilityThe reproducibility, R, of this testmethod has been established as the appropriate value for anyparameter as tabulated in Table 1. Two single test resultsobtained in two different laboratories, under normal testmethod procedures, tha
43、t differ by more than this tabulated Rmust be considered as derived from different or nonidenticalsample populations.10.8 Repeatability and reproducibility expressed as a per-centage of the mean level (r) and (R) have equivalent applica-tion statements as 10.6 and 10.7 for r and R. For the (r) and (
44、R)statements, the difference in the two single test results isexpressed as a percentage of the arithmetic mean of the two testresults.10.9 BiasIn test method terminology, bias is the differ-ence between an average test value and the reference (or true)test property value. Reference values do not exi
45、st for this testmethod since the value (of the test property) is exclusivelydefined by the test method. Bias, therefore, cannot be deter-mined.NOTE 1Appearance of a band at wavenumber 696 cm1in theinfrared spectrum indicates inadequate purification.NOTE 2Some grades of hydrogenated nitrile rubber ex
46、hibit an addi-tional nitrile band at wavenumber 2214 cm1. In this case, calculate A(ACN) = A (2236) + A (2214) and use A (ACN) for further calculations.NOTE 3Sr= within-laboratory standard deviation; r = repeatability(in measurement units); (r) = repeatability (as percent of material aver-age); SR=
47、between-laboratory standard deviation; R = reproducibility (inmeasurement units); (R) = reproducibility (as percent of material average).11. Keywords11.1 HNBR; hydrogenated nitrile rubber; infrared spectrom-etry (IR); unsaturation5Supporting data have been filed at ASTM International Headquarters an
48、d maybe obtained by requesting Research Report RR: D11-1072.TABLE 1 Type 1 Precision: Residual Unsaturation (RU) of HNBR(see Note 3)HNBRNominal%ACN%RUMeanWithin Laboratory Between LaboratorySrr (r) SRR (R)#1 33 0.65 0.119 0.337 51.8 0.172 0.486 74.8#2 36 2.3 0.111 0.314 13.7 0.149 0.421 18.3#3 36 5.
49、1 0.179 0.506 9.9 0.348 0.984 19.3D 5670 95 (2009)3APPENDIX(Nonmandatory Information)X1. EXAMPLEX1.1 HNBR, Medium ACN, Partially Unsaturated:X1.2 Calculation of Unsaturation:( Ai! 5 1 10.1192.310.4310.2555 2.742 (X1.1)cACN! 512.7425 0.365 (X1.2)cBD! 50.1192.3 3 2.7425 0.019 (X1.3)cHBD! 50.4310.255 3 2.7425 0.616 (X1.4)Unsaturation 50.0190.019 1 0.6163 100 5 3 % (X1.5)TABLE X1.1 HNBR, Medium ACN, Partially UnsaturatedCorrected AbsorbanceNormalizedAbsorbance RatioAA(2236) A(970) A(723) A(970) A(723)Baseline 22802200 100
