1、Designation: D5477 18Standard Practice forIdentification of Polymer Layers or Inclusions by FourierTransform Infrared Microspectroscopy (FT-IR)1This standard is issued under the fixed designation D5477; the number immediately following the designation indicates the year oforiginal adoption or, in th
2、e 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 practice describes the techniques used for detectingtwo different polymer entitie
3、s such as:1.1.1 Abnormal specks or spots on a surface or in the filmthat are objectionable as defects and1.1.2 Layers of different polymeric sheets commonly usedas barrier films made by coextrusion.1.2 This practice utilizes through-transmittance optical andinfrared techniques.1.3 The values stated
4、in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 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, heal
5、th, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Specific hazard statements are given in Section 7.NOTE 1There is no known ISO equivalent to this standard.1.5 This international standard was developed in accor-dance with internationally recogniz
6、ed principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relatin
7、g to PlasticsD1248 Specification for Polyethylene Plastics ExtrusionMaterials for Wire and CableD1600 Terminology forAbbreviated Terms Relating to Plas-ticsE131 Terminology Relating to Molecular SpectroscopyE168 Practices for General Techniques of Infrared Quanti-tative AnalysisE2015 Guide for Prepa
8、ration of Plastics and PolymericSpecimens for Microstructural ExaminationIEEE/ASTM SI-10 Standard for Use of the InternationalSystem of Units (SI):The Modern Metric System3. Terminology3.1 Definitions:3.1.1 For definitions of the terms used in this practice, referto Terminologies D883 and D1600.3.1.
9、2 For units, symbols, and abbreviations used in thispractice, refer to Terminology E131 or IEEE/ASTM SI-10.4. Significance and Use4.1 Aspeck will ultimately cause a failure to occur by virtueof its appearance in a film or by the decrease in electrical ormechanical properties in the polymer substrate
10、 (see Specifica-tion D1248).4.2 The analysis of composite layers for barrier purposes bymicroscopic Fourier transform infrared spectroscopy (FT-IR)can indicate the adequacy of the barrier tape or indicate why abarrier may be defective (a missing layer or hole in the layer orpoor coextrusion practice
11、). Fig. 1 represents a typical multi-layer film.5. Apparatus5.1 FT-IR Spectrophotometer, with nominal 4-cm1resolu-tion (see Practices E168).5.2 Microsampling Accessory, accommodated into theFT-IR for microscopic infrared analysis, with nominal 6.25-mresolution in the infrared mode.5.3 Optical Micros
12、cope, equipped with cross-polarized lightand phase contrast accessories. May be incorporated into theinfrared microsampling accessory.5.4 Hot-Stage, with temperature readout, is accommodatedinto the optical microscope or microsampling accessory.5.5 Microtome, capable of 25 m slices 62.5 m.1This prac
13、tice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved Aug. 1, 2018. Published August 2018. Originallypublished as D5477 93. Last previous edition approved in 2011 as D5477 11.DOI: 10.1520/
14、D5477-18.2For 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.*A Summary of Changes section appears at the end of
15、this standardCopyright ASTM International, 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 theDevelop
16、ment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.16. Material6.1 Stiff plastic at 25C, 1.25 mm thick and large enough tohold sample (for example, ABS, boPET).6.2 Cyano-acrylate adhesive.6.3 Thermoset materi
17、al for encapsulating sample (forexample, 2-part epoxy, acrylic).6.4 Glass microscope slide to support sample slice duringinspection.7. Hazards7.1 The FT-IR spectrophotometer contains a laser. To avoideye injury, do not stare directly into the laser beam.7.2 Use gloves when samples are prepared. The
18、cyano-acrylate adhesive will attach itself to the fingers and skin. Takecare to prevent this from occurring.7.3 Avoid burns when handling microscopic slides with thehot-stage.8. Specimen Preparation8.1 It is necessary to microtome a thin cross section at rightangles to the surface of the film or sam
19、ple in order toconveniently observe the individual layers or the interior of thespeck.8.2 Samples that do not deflect can be microtomed into therequired thin sections as received.8.3 Flexible samples must be supported during sectioning.Two common support techniques are shown, for flexiblesamples, in
20、 Fig. 2. On the left, a stiff, flat plastic is used for thesupport. A cyano-acrylate adhesive quickly bonds the flexiblesample to the flat plastic support. On the right of Fig. 2, thesample is supported and cured inside a thermoset compound,such as a two-part epoxy. (See Guide E2015.)8.4 The entire
21、sandwich is then microtomed in a directionnormal to the sample surface. Slice thickness typically of 25-50m provide satisfactory transmission of optical and infraredlight.FIG. 1 Position and Function of Materials in a Typical Multilayer FilmFIG. 2 Sandwich for Thin FilmsD5477 1829. Procedure9.1 Opti
22、cal Microscopy9.1.1 The first step is to observe the sample visually in anoptical microscope. The fundamentals of optical microscopyand sample preparation have been discussed in detail else-where.39.1.2 The key to optical microscopy analysis is the samplepreparation. A 25 to 50-m thick section allow
23、s the visible andIR radiation to go through the section. A section with very fewknife marks is required. A knife mark is a gouge created in thesection by a defect in the microtome knife. Under cross-polarized light, knife marks will confuse and distort theboundaries of an inhomogeneity or layers in
24、a multilayerspecimen.9.1.3 Once suitable sections have been collected, they areviewed in the optical microscope under cross-polarized light.In pigmented materials, it is also necessary to view thematerials in uncrossed polarized light. Differences in contrastbetween inhomogeneities of layers develop
25、 in these situationsdue to differences in the intrinsic birefringence of the resins,thermal and stress history, and pigment concentration. Thedifferences in contrast generally define material boundaries.The areas of interest may then be photographed and measure-ments made to quantify the dimensions
26、of inhomogeneities orlayers.9.1.4 Since differences in contrast may arise from factorsother than chemical differences, it is necessary to conduct ahot-stage microscopic analysis. In the hot-stage, each of thedifferent materials is located when their birefringence disap-pears in the microscope under
27、cross-polarized light, in accor-dance with their melting temperature. The hot-stage is heatedat a rate of up to 10C/min. It is advisable to recrystallize thepolymers and recheck the melting points since processinghistory may influence softening point upon first melting in thehot-stage.9.2 Infrared M
28、icroscopy9.2.1 The infrared microscope permits the identification ofinclusions and multilayer films down to diameters of 10 m.9.2.2 This procedure uses the microscope to locate andanalyze small areas of a specimen. The microscope mates witha FT-IR spectrometer. Infrared spectra may then be obtainedf
29、or each small area of interest.9.2.3 A schematic of an instrument capable of performingthese tasks is shown in Fig. 3. This microscope accessory isvery useful for locating and then identifying smallinhomogeneities, such as a particle, oxidized zone, or layer ina plastic film. Its use is unique for t
30、he identification of the3Chamot, E. M., and Mason, C. W., Handbook of Chemical Microscopy, JohnWiley and Sons, Inc., New York, NY, 1985.FIG. 3 Schematic of An Infrared Microsampling Accessory with Viable Lenses and Polarizers Built InD5477 183layers in a multilayer film or sheet. The area of interes
31、t ischemically identified by the interpretation of the infraredspectra obtained for that area.9.2.4 The infrared microscope is focused on the area ofinterest within the section. This typically requires using aper-tures to isolate the area. All spectra are recorded at 4 cm1resolution. Acceptable sign
32、al-to-noise ratios are obtained bythe co-adding at least 100 spectra.9.2.5 Many unresolved peaks in the spectrum indicatesections need to be thinner, assuming apertures, gain, and otherparameters optimized.9.2.6 A well-resolved spectrum, along with the estimatedmelting point, may now be used to aid
33、in chemical identifica-tion.10. Report10.1 Report the following information:10.1.1 Preparation method,10.1.2 Material(s) identification,10.1.3 Method(s) of determination,10.1.4 The date of the test.11. Keywords11.1 Fourier transform infrared spectroscopy; microscopy;microsampling; cross-polarizedAST
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