ASTM_D_5670_-_95_2014.pdf

Designation:D567095(Reapproved 2014)Standard Test Method forRubberDetermination of Residual Unsaturation inHydrogenated Nitrile Rubber(HNBR)by InfraredSpectrophotometry1This standard is issued under the fixed designation D5670;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 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 residualunsaturation(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 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 spectrophotometry 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 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:2D4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustriesE932 Practice for Describing and Measuring Performance ofDispersive Infrared SpectrometersE1421 Practice for Describing and Measuring Performanceof Fourier Transform Mid-Infrared(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 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 absorptionbands 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.Significance 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 radiation.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 anddevelopment,quality control,and referee purposes.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 Aug.1,2014.Published November 2014.Originallyapproved in 1995.Last previous edition approved in 2009 as D5670 95(2009).DOI:10.1520/D5670-95R14.2For 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.3Brck,D.,Kautschuk,Gummi,Kunststoffe,Vol 42,1989,pp.107110 and194197.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Apparatus5.1 Preparation of Rubber Solution:5.1.1 Erlenmeyer Flask with Ground Glass Stopper,(50cm3).5.1.2 Flask Shaker.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,withtemperature control.5.5 Spectrophotometer,required resolution capability of 2cm1.The instrument must be in good operating condition asdefined by the manufacturer and Practices E932 and E1421.The instrument shall be capable of scale expansion along theabsorbance