1、Designation: D7399 18Standard Test Method forDetermination of the Amount of Polypropylene inPolypropylene/Low Density Polyethylene Mixtures UsingInfrared Spectrophotometry1This standard is issued under the fixed designation D7399; the number immediately following the designation indicates the year o
2、foriginal 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. Scope*1.1 This test method uses an infrared spectrometer fordetermi
3、ning the amount of polypropylene (PP) physicallymixed in with low density polyethylene usually for recyclingpurposes.NOTE 1Quantitative determinations require several standard mixturesin the concentration range of interest and well defined baseline anchoringpoints. See Practice E168 for guidance.1.2
4、 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.NO
5、TE 2There is no known ISO equivalent to this standard.1.3 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issue
6、d by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.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 cm1E13
7、1 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 (
8、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 and D1600.3.2 TerminologyUni
9、ts, 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 infrared spectrophotometer using twoabsorbance bandsone characteristic for PP and one forLDPE
10、. The ratio of these two absorbencies is used to assess thepresence of polypropylene.4.2 For quantitative determinations, several standards withknown concentrations of PP in LDPE bracketing the range ofinterest are needed to develop a calibration curve. In addition,baseline placement process is defi
11、ned so as to produce repeat-able results.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 composition of the mixture is.6. Interferences6.1 Presence of materials other than PPor LDPE in a samplec
12、an cause error in measurement.6.2 Inhomogeneity of sample is known to cause falsereadings. It is recommended to verify the sample homogeneityby measuring at least three different areas of the sample.1This test method is under the jurisdiction ofASTM Committee D20 on Plasticsand is the direct respons
13、ibility of Subcommittee D20.70 on Analytical Methods.Current edition approved April 1, 2018. Published April 2018. Originallyapproved in 2008. Last previous edition approved in 2008 as D7399-08, which waswithdrawn February 2017 and reinstated in April 2018. DOI: 10.1520/D7399-18.2For referenced ASTM
14、 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM I
15、nternational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standar
16、ds, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.17. Apparatus7.1 Infrared Spectrophotometer, either double beam or aFourier transform.7.1.1 Double-Beam Infrared Spectrophotometer, capable ofat least 4 cm-1spectral resolution as define
17、d in Practice E932.The instrument shall be capable of scale expansion along thewavelength axis.7.1.2 Fourier Transform Infrared Spectrometer (FTIR), ca-pable of at least 4 cm-1resolution. The instrument shall becapable of scale expansion along the wavelength axis.Also, seePractice E1421.7.2 Film Mou
18、nts, to hold the film specimens in the infraredspectrophotometer.NOTE 3Attenuated Total Reflectance (ATR) methodology is accept-able as an alternative to the transmission mode. The sample shall be testedusing the same mode and settings as that used to build the calibrationcurve.8. Hazards8.1 The opt
19、ical 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 absorbences of 1.5 unitsor less on the spectrum. Thickness of approximately 0.025 mm(1 mil) has been found adequate.
20、NOTE 4For samples not available in the proper thickness range, thefilms can be produced on any suitable cast or blown film unit usingappropriate conditions that will produce films of uniform thickness andappearance.9.2 Spectral Measurements:9.2.1 Place the sample in the infrared spectrophotometer.9.
21、2.2 Set the controls of the infrared spectrophotometer togive a good signal to noise ratio. Increasing the number ofscans if a larger signal to noise ratio is required. User definedquality objectives will define the minimum signal to noiseratio.Aspectral resolution of 4 cm-1, a Beer-Norton medium or
22、Happ-Genzel apodization function and 32 scans have beenfound to be appropriate.9.2.3 Record the infrared spectrum starting from at least4000 cm-1to 700 cm-1or lower.9.3 Determine the absorbance of the peaks at 13731378cm-1(hereafter referred to the 1378 cm-1peak) and 14601465cm-1(hereafter referred
23、to the 1465 cm-1peak) one character-istic for PP and one for LDPE. Draw baseline between 1200cm-1and 1600 cm-1and use it for both peaks. See PracticeE168 and Test Methods D2238 for guidance.NOTE 5When there is a clear valley between the 1378 cm-1and 1465cm-1peaks, then individual baselines can be us
24、ed (see Practice E168 formore guidance).9.4 At least five LDPE standards with known concentrationsof PPare needed to develop a calibration curve. The type of PP(for example, homopolymer, heterophasic, random) and prepa-ration of the polymeric materials will affect the relative peakheights. Therefore
25、, the standards shall be representative of thePP type or mixture of polymers used.9.5 The absorbance ratio of the 1378 cm-1and 1465 cm-1peak heights is plotted against PP concentration (see Fig. 1).The PP content of the unknown sample is obtained by crossreferencing this ratio on the calibration lin
26、e.9.6 Use the average of at least three measurements forcalibration curve. The coefficient of determination shall be atleast 0.95 for the best-fit line. (See Fig. 1.)9.7 Measure the absorbance ratio of the unknown sampleusing the same baseline anchoring points as used for theFIG. 1 Example of a Cali
27、bration CurveD7399 182calibration curve. Calculate the amount of PP from the cali-bration curve using the ratio.10. Report10.1 Report the following information:10.1.1 Complete identification of material tested includingname, manufacturer, lot number and physical form whensampled.10.1.2 Date of test.
28、10.1.3 Testing was done in accordance with Test MethodD7399.10.1.4 Any sample or spectral anomalies observed duringthe measurement.10.1.5 Results from the analysis including the ratio orpercentage of PP in the mixture.11. Precision and Bias11.1 An unknown sample was measured ten times. Theaverage co
29、ntent of PP is 26.0 % with a standard deviation of1.2 %.12. Keywords12.1 infrared spectrophotometry; low density polyethylene;polypropyleneSUMMARY OF CHANGESCommittee D20 has identified the location of selected changes to this standard since the last issue (D739908)that may impact the use of this st
30、andard. (April 1, 2018)(1) Title: Removed abbreviations from title and spelled out allwords.(2) All: Throughout the document, editorial changes weremade for easier understanding or correction of spelling orgrammar mistakes.(3) All: Throughout the doc, reference to A1373 cm-1peak ismade. It should be
31、 1378 cm-1.(4) 3.1: Removed reference to D5033 (obsolete)(5) 4.1: Replaced acronyms with spelled out words for clarity.(6) 4.2: Cleaned up sentence for clarity.(7) 5.1, 6.2, 7: Removed sentences, abbreviations due toambiguity.(8) Fig. 1: Changed y-axis title to use A1378, not 1373 cm-1.(9) Section 9
32、: Removed Note 5, reworded Note 6.(10) 9.4: Reworded.(11) 9.5: Reworded and split up between 9.5 and 9.6.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that
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