ASTM_D_7399_-_08.pdf

Designation:D739908Standard Test Method forDetermination of the Amount of Polypropylene(PP)inPolypropylene/LDPE Mixtures Using InfraredSpectrophotometer(FTIR)1This standard is issued under the fixed designation D7399;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 uses an infrared approach for deter-mining the presence of polypropylene(PP)physically mixed inwith low density polyethylene usually for recycling purposes.NOTE1Quantitative determinations require several standard mixturesin the concentration range of interest and well defined baseline anchoringpoints.1.2 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.NOTE2There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1600 Terminology forAbbreviated Terms Relating to Plas-ticsD2238 Test Methods forAbsorbance of Polyethylene Due toMethyl Groups at 1378 cm1D5033 Guide for Development ofASTM Standards Relatingto Recycling and Use of Recycled Plastics(Withdrawn2007)3E131 Terminology Relating to Molecular SpectroscopyE168 Practices for General Techniques of Infrared Quanti-tative AnalysisE932 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 TestsIEEE/ASTM SI-10 Standard for Use of the InternationalSystem of Units(SI):The Modern Metric System3.Terminology3.1 DefinitionsFor definitions of plastics terms used inthis test method,see Terminology standards D883,D1600,andD5033.3.2 TerminologyUnits,symbols,and abbreviations used inthis test method appear in Terminology E131 or IEEE/ASTMSI-10.4.Summary of Test Method4.1 Thin films representing a typical portion of the materialare analyzed with an IR spectrophotometer using two absor-bance bandsone characteristic for polypropylene(PP)andone for low density polyethylene(LDPE).The ratio of thesetwo absorbencies is used to assess the presence of polypropyl-ene.4.2 For quantitative determinations,several standards withknown concentrations of PP in LDPE bracketing the range ofinterest are needed to develop a calibration curve.Also,baseline placement shall be defined to produce repeatableresults.5.Significance and Use5.1 In recycling PP and LDPE,it is important to the endproduct properties as well as to the processing conditions toknow what the purity of the mixture is.In many cases,it is vitalto know that the recycled material is reasonably free of acontaminant.6.Interferences6.1 Presence of materials other than PPor LDPE in a samplemight cause error in measurement.6.2 Inhomogeneous sample is known to cause false reading.It is recommended to verify sample homogeneity by measuringdifferent areas of the sample.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved Sept.1,2008.Published September 2008.DOI:10.1520/D7399-08.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Apparatus7.1 Infrared Spectrophotometer,either double beam or aFourier transform(FTIR).7.1.1 Double-Beam Infrared Spectrophotometer,capable ofa 4 cm-1spectral resolution as defined in Practice E932.Theinstrument shall be capable of scale expansion along thewavelength axis.7.1.2 Fourier Transform Infrared Spectrometer,capable of 4cm-1resolution.The instrument shall be capable of scaleexpansion along the wavelength axis.Also,see Practice E1421for testing procedures.7.2 Film Mounts,with apertures at least 6 by 27 mm,to holdthe film specimens in the infrared spectrophotometer.NOTE3Attenuated Total Reflectance(ATR)methodology is accept-able as an alternative to the transmission mode.For best results,sampleshall be tested using the same mode as the calibration curve.8.Hazards8.1 The optical bench of the FTIR spectrometer contains alaser.To avoid eye injury,do not look directly into the laserbeam.9.Procedure9.1 Sample Preparation:9.1.1 Use film specimens that give absorbencies 1.5 units orless on IR scan.Thickness of approximately 0.025