ASTM D5576-2000(2006) Standard Practice for Determination of Structural Features in Polyolefins and Polyolefin Copolymers by Infrared Spectrophotometry (FT-IR)《用付里叶变换红外光谱(FT-IR)法测定.pdf

1、Designation: D 5576 00 (Reapproved 2006)Standard Practice forDetermination of Structural Features in Polyolefins andPolyolefin Copolymers by Infrared Spectrophotometry (FT-IR)1This standard is issued under the fixed designation D 5576; the number immediately following the designation indicates the y

2、ear 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice covers infrared procedures for determ

3、iningthe molecular structural features in polyolefins and polyolefincopolymers. The structural features of primary concern are thetypes and numbers of branches. Although this practice centersits attention on polyolefins and polyolefin copolymers, thetechniques, with proper modification, can be used

4、for someother polymers as well.NOTE 1Quantitative determinations require either an internal or anexternal evaluation of sample thickness. ASTM test methods available forspecific features are listed in Tables 1 and 2.1.2 This standard does not purport to address all of thesafety concerns, if any, ass

5、ociated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and to determine theapplicability of the regulatory limitations prior to use.NOTE 2There is no similar or equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards

6、:2D 883 Terminology Relating to PlasticsD 1505 Test Method for Density of Plastics by the Density-Gradient TechniqueD 1600 Terminology for Abbreviated Terms Relating toPlasticsD 2238 Test Methods for Absorbance of Polyethylene Dueto Methyl Groups at 1378 cm1D 3124 Test Method for Vinylidene Unsatura

7、tion in Poly-ethylene by Infrared SpectrophotometryD 3594 Test Method for Copolymerized Ethyl Acrylate InEthylene-Ethyl Acrylate CopolymersD 5594 Test Method for Determination of the Vinyl AcetateContent of Ethylene-Vinyl Acetate (EVA) Copolymers byFourier Transform Infrared Spectroscopy (FT-IR)D 62

8、48 Test Method for Vinyl and Trans Unsaturation inPolyethylene by Infrared SpectrophotometryE 131 Terminology Relating to Molecular SpectroscopyE 168 Practices for General Techniques of Infrared Quanti-tative AnalysisE 932 Practice for Describing and Measuring Performanceof Dispersive Infrared Spect

9、rometersE 1421 Practice for Describing and Measuring Performanceof Fourier Transform Mid-Infrared (FT-MIR) Spectrom-eters: Level Zero and Level One TestsIEEE/ASTM SI10 Standard for Use of the InternationalSystem of Units (SI): The Modern System3. Terminology3.1 Definitions For definitions of plastic

10、s terms used inthis practice see Terminology D 883 and D 1600.3.2 Units, symbols and abbreviations used in this practiceappear in Terminology E 131 or IEEE/ASTM SI-10.4. Summary of Practice4.1 Infrared absorption bands suitable for quantitativeanalysis by FT-IR are listed in Tables 1 and 2. These ar

11、e onlytypical bands and are not to be construed as exhaustive.4.2 For quantitative determinations, sample specimen thick-ness is measured internally at some band representing the basicchain structure, such as 2019 cm1for polyethylene, orexternally using a micrometer (see Tables 1 and 2 for ASTMtest

12、methods).NOTE 3Warning: Molding can cause carbonyl formation due tooxidation. This should be checked in the 1700 to 1750 cm1range.5. Significance and Use5.1 The structural features expressed by these determina-tions affect the ultimate polymeric properties and are useful inshowing correlations with

13、many performance properties.1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved Sept. 1, 2006. Published September 2006. Originallyapproved in 1994. Last previous edition appro

14、ved in 2000 as D 5576 - 00.2For 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.1*A Summary of Changes section app

15、ears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus6.1 Infrared Spectrophotometer, either double beam or aFourier transform (FT-IR).6.1.1 Double-beam infrared spectrophotometer capable of a4cm

16、-1spectral resolution as defined in Practice E 932. Theinstrument should be capable of scale expansion along thewavelength axis.6.1.2 Fourier Transform Infrared Spectrometer, capable of4cm1resolution. The instrument should be capable of scaleexpansion along the wavelength axis.Also, see Practice E 1

17、421for testing procedures.6.2 Hot Plate.6.3 Microscope Slides.6.4 Compression-Molding Press, capable of 200C.6.5 Metal Plates, two, 150 by 150 mm or larger, of 0.5mmthickness with smooth surfaces.6.6 Brass Shims, approximately 75 by 75 mm, of 0.5-mmthickness with an aperture in the center at least 2

18、5 by 38 mm.6.7 Micrometer (optional), with thimble graduations of0.001 mm.6.8 Film Mounts, with apertures at least 6 by 27 mm, to holdthe specimens in the infrared spectrophotometer.7. Materials7.1 Polyethylene Terephthalate, Aluminum or Matte Fin-ished Teflon-Fiberglass Sheets.8. Hazards8.1 Wear gl

19、oves when plaques are prepared using a heatedpress.8.2 The optical bench of the FT-IR spectrometer contains alaser. To avoid eye injury, do not look directly into the laserbeam.9. Procedure9.1 Sample Preparation:9.1.1 Procedure A:9.1.1.1 Control the hot plate temperature at 100 6 10Cabove the meltin

20、g temperature of the polymer.9.1.1.2 Place a portion of the sample on a microscope slideon the hot plate.9.1.1.3 Cover the sample with another slide and press witha wooden pestle. Use firm circular motions to press a uniformfilm.9.1.1.4 To quench the pressed polymer film, dip the twoslides carefully

21、 into a beaker of cold water. Remove the filmand blot dry.9.1.2 Procedure B:9.1.2.1 Preheat the press to about 50C above the meltingpoint of the polymer.9.1.2.2 Place a brass shim on the sheet material chosen (see7.1) that, in turn, covers a metal plate.9.1.2.3 Add polymer in sufficient quantity to

22、completely fillthe shim aperture during pressing.9.1.2.4 Cover with another piece of sheet (see 7.1) andanother metal plate.9.1.2.5 Insert the mold assembly between the press platensand apply a slight pressure.9.1.2.6 Allow the sample to preheat for about 30 s. Applythe full press pressure at a temp

23、erature approximately 50Cabove the melting point of the polymer for 1 min or until allexudation ceases.9.1.2.7 Turn off the heat, turn on the cooling water, andallow the sample to press quench at full pressure until thetemperature drops below 50C (or cool enough to remove themold assembly by hand).9

24、.1.2.8 Release the pressure and remove the sample.9.1.2.9 Select plaques that are clear and of uniform thick-ness for the FT-IR analysis. To avoid interference fringes in thespectrum, the plaque/film surfaces must be slightly dimpled.9.2 Spectral Measurements:9.2.1 Place the sample in the infrared s

25、pectrophotometer.9.2.2 Set the controls of the infrared spectrophotometer forquantitative conditions with a good signal to noise ratio andsatisfactory repeatability. For a FT-IR, a spectral resolution of4cm1and an apodization function (Beer-Norton medium andHapp-Genzel have been found to be appropri

26、ate) that givesgood quantitation should be used.9.2.3 Record the infrared spectrum from 4000 to 500 cm1.9.2.4 Determine which structural feature(s) are present andselect the appropriate ASTM method for quantitative determi-nation.10. Calculation10.1 If no standard method is available and an estimate

27、 ofthe concentration of the feature of interest is sought, theapproach in 10.1.1-10.1.3 is suggested.10.1.1 Determine the thickness of the plaque or, preferably,its spectral cross-section, b,incm2/g, by measuring thethickness and density or alternatively the mass and surface areaof a uniformly thick

28、 portion of the plaque10.1.2 Measure the absorbance of the peak of interest.Choose a baseline between valleys on either side of the peak ina manner to produce the most accurate and repeatable repre-sentation of the actual background absorbanceTABLE 1 Polyolefin Structural Features Determined by FT-I

29、RStructure Absorption Band, cm1ASTM Test MethodMethyl group (polyethylene) 1378 D 2238Methyl group (eth-prop copol) 1380Pendant methyl 935Terminal vinyl 908 D 6248Trans-vinylene 965 D 6248Vinylidene 888 D 3124TABLE 2 Structural Features in Polyolefin CopolymerDetermined by FT-IRStructure Absorption

30、Band, cm1ASTM Test MethodVinyl acetate 609 D 55941020 D 55943270 D 5594Styrene 77070016001500Ethyl acrylate 16401730862 D 3594Ethylene acrylate 1280120016401625D 5576 00 (2006)210.1.3 Calculate the concentration, c, of the feature usingeither the Beer-Lambert Law (A = a b c) with the appropri-ate mo

31、lar absorptivity, a, or an appropriate calibration curve. Ifa calibration curve is used, it should have a minimum of 5 datapoints, and the unknown should be within the high and lowlimits of the standards.11. Report11.1 Report the following information:11.1.1 Complete identification of material teste

32、d includingname, manufacturer, lot number and physical form whensampled,11.1.2 Date of test, and11.1.3 Any sample or spectral anomalies observed duringthe measurement.12. Keywords12.1 copolymers; FT-IR; infrared spectrophotometry; poly-ethylene; structural featuresSUMMARY OF CHANGESCommittee D20 has

33、 identified the location of selected changes to this standard since the last issue(D 5576 - 00) that may impact the use of this standard. (September 1, 2006)(1) Reapproved without change.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any

34、 item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical

35、committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at

36、 a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor D

37、rive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 5576 00 (2006)3