1、Designation: D 3452 06Standard Practice forRubberIdentification by Pyrolysis-Gas Chromatography1This standard is issued under the fixed designation D 3452; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.PART 1. IDENTIFICATION OF SINGLE POLYMERS1. Scope1.1 This pract
3、ice covers the identification of polymers inraw rubbers, and cured and uncured compounds, based on asingle polymer, by the gas chromatographic patterns of theirpyrolysis products (pyrograms). Implementation of this guidepresupposes a working knowledge of the principles and tech-niques of gas chromat
4、ography, sufficient to carry out thispractice and to interpret the results correctly.21.2 This practice will identify the following polymers:1.2.1 Polyisoprene of natural or synthetic origin,1.2.2 Butadiene-styrene copolymers,1.2.3 Polybutadiene,1.2.4 Polychloroprene,1.2.5 Butadiene-acrylonitrile co
5、polymers,1.2.6 Ethylene-propylene copolymers and related terpoly-mers, and1.2.7 Isobutene-isoprene copolymers.1.3 This practice will not differentiate the following poly-mers:1.3.1 Natural polyisoprene from synthetic polyisoprene.1.3.2 Butadiene-styrene copolymers produced by solutionand emulsion po
6、lymerization. It is sometimes possible todistinguish butadiene-styrene copolymers containing differentamounts of styrene as well as random polymers from blockpolymers.1.3.3 Polybutadiene with different microstructures.1.3.4 Different types of polychloroprenes.1.3.5 Butadiene-acrylonitrile copolymers
7、 with differentmonomer ratios.1.3.6 Ethylene-propylene copolymers with different mono-mer ratios, as well as the copolymers from the related terpoly-mers.1.3.7 Isobutene-isoprene copolymers (butyl rubbers) fromhalogenated butyl rubbers.1.3.8 Polyisoprene containing different amounts of cis-transisom
8、ers.1.3.9 The practice does not identify ebonite or hard rubbers.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It i
9、s 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:3D 297 Test Methods for Rubber ProductsChemicalAnalysisE 260 Practice for Packed Co
10、lumn Gas ChromatographyE 355 Practice for Gas Chromatography Terms and Rela-tionships3. Significance and Use3.1 For research, development, and quality control pur-poses, it is advantageous to determine the composition ofrubbers in cured, compounded products.3.2 This practice provides such compositio
11、n analysis, uti-lizing a gas chromatograph and pyrolysis products from rubberdecomposition.4. Principle of the Practice4.1 This practice is based upon comparison of the gaschromatographic pattern of the pyrolysis products of a knownrubber with an unknown rubber. The results of this separationwill he
12、reafter be referred to as the pyrogram.4.2 The pyrogram of the known rubber is filed for futurereference. The pyrogram of the unknown rubber is compared tothis for identification.1This practice is under the jurisdiction of ASTM Committee D11 on Rubber andis the direct responsibility of Subcommittee
13、D11.11 on Chemical Analysis.Current edition approved Oct. 1, 2006. Published November 2006. Originallyapproved in 1975. Last previous edition approved in 2002 as D 3452 93 (2002).2Definitions of terms and general directions for the use of gas chromatographymay be found in Practices E 355 and E 260.3
14、For 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C
15、700, West Conshohocken, PA 19428-2959, United States.4.3 The success of the method depends upon examining theknown and unknown rubbers under exactly the same experi-mental conditions.4.4 The qualitative composition of the pyrolysis productsdepend upon the type of polymer being studied.4.5 The quanti
16、tative composition of the pyrolysis productsmay be affected by the degree of cure, and recipe used, etc., butthe most important factor is the type of pyrolysis device.5. Apparatus5.1 Pyrolysis DevicesThe applicability of this practice hasbeen checked on the following types:5.1.1 Quartz Tubes, electr
17、ically heated at a prefixed tem-perature. The volatile products enter the chromatographthrough heated tubing.5.1.2 Platinum Filaments, electrically heated. Pyrolysis iscarried out within the chromatograph inlet and immediatelyswept into the column by the carrier gas.5.1.3 Small Coils of Ferromagneti
18、c Wire, heated to theCurie point temperature. The volatile products enter the gaschromatograph through heated tubing.5.2 Gas ChromatographThe applicability of this practicehas been checked on a wide variety of gas chromatographs,employing both flame ionization and thermal conductivitydetectors. Any
19、commercially available instrument is satisfac-tory. Dual-column operation and temperature programming isstrongly recommended, but not mandatory.5.3 Gas Chromatographic ColumnsThe applicability ofthis practice has been checked on a wide variety of columnlengths, diameters, supports, and liquid phases
20、. The onlyrequisite is that there be sharp separation between the follow-ing: isobutene, butadiene, isoprene, vinylcyclohexene, styrene,and dipentene.5.4 Carrier GasThe applicability of this practice has beenchecked with both helium and nitrogen as the carrier gas. Bothare satisfactory.6. Sample Siz
21、e6.1 For thermal conductivity detection and electricallyheated platinum filaments, a sample size of approximately3 mg has been found satisfactory. This could be increased ordecreased depending on the composition of the sample and thecapacity of the probe.6.2 For flame ionization and either Curie poi
22、nt apparatus orelectrically heated platinum filaments, a sample size rangingfrom 0.2 to 2.0 mg has been found satisfactory.7. Procedure7.1 ExtractionAlthough not mandatory, some benefitsmay be obtained from extraction of the sample according toTest Methods D 297, Sections 18 and 25. If the sample ha
23、sbeen extracted prior to obtaining the pyrogram, the knownmust also be extracted.7.2 PyrolysisThe following conditions apply to the threetypes of pyrolysis devices in 5.1:7.2.1 Quartz Tubes (5.1.1)Place 1 to 5 mg of sample in asmall quartz or porcelain boat in the cold part of the pyrolysistube. Sto
24、pper the tube and flush with carrier gas. Transfer theboat to the hot part of the tube, maintained at 500 to 800C.Length of the time depends upon the pyrolysis device; how-ever, time and temperature must be kept constant. To minimizecondensation, convey the volatile pyrolysis products into thegas ch
25、romatograph through tubing heated to a known, fixedtemperature, but slightly higher than the gas chromatographinlet. Record the pyrogram.7.2.2 Electrically Heated Platinum Filaments (5.1.2)Place the required amount of sample in the pyrolysis probe.Insert it into the injection port of the gas chromat
26、ograph andallow the base line to stabilize. Energize the probe, using theprocedure recommended by the manufacturer of the unit toobtain temperatures of 800 to 1200C.7.2.3 Curie Point Apparatus (5.1.3)Place the requiredamount of sample in the coils of ferromagnetic wire or wrapthe wire securely aroun
27、d the required amount of sample andpyrolyze according to the manufacturers directions for properuse of the unit. Energize the apparatus to obtain the requiredtemperature of 550 to 650C (depending on the composition ofthe alloy used for the wire) and introduce the pyrolysisproducts into the gas chrom
28、atograph. Record the pyrogram.7.3 Separation of the Volatile Pyrolysis ComponentsAsstated in 5.3, a wide variety of columns may be used. As anexample, the following describes the separation of volatilepyrolysis components by means of suitable columns. Analysisof the products of polyisoprene pyrolysi
29、s are used in thisexample. In all cases, equivalent materials may be used.7.3.1 Polar Liquid PhaseStainless steel tubing, 4 to 6 mlong, with an outside diameter of 3.2 mm (18 in.), packed with10 to 20 % di (2-ethylhexyl)sebacate on a 150 to 180-mdiatomaceous silica support.4Carrier gas flow of 0.2 t
30、o0.3 cm3/s. Inlet and detector temperature at 170C. Oventemperature 50C isothermal until isoprene is completelyeluted, then program at 20 to 40C/min to 150C and maintainat this temperature until the dipentene is eluted.7.3.2 Non-Polar Liquid PhaseStainless steel tubing, 3 mlong, with an outside diam
31、eter of 3.2 mm (18 in.), packed with10 % high vacuum grease on a 150 to 180-m diatomaceoussilica support. Carrier gas flow of 0.12 to 0.83 cm3/s. Inlettemperature of 170 to 200C. Oven temperature at 50Cisothermal for 3 min or until isoprene is eluted, then raise thetemperature to 130 to 150C at 4 to
32、 6C/min. Maintain at thehigher temperature until the dipentene is eluted.8. Rubber Identification (Interpretation of the Pyrogram)8.1 Each rubber type shows a distinctive pyrogram, underthe same pyrolysis and gas chromatographic conditions.8.2 Identification is achieved by comparing the pyrogram oft
33、he sample rubber (unknown) to the pyrogram of the knownrubber, under exactly the same operating conditions.4The sole source of supply of diatomaceous silica (Chromosorb P) known to thecommittee at this time is Johns-Manville Products Corp., Celite Div., 22 E. 40th St.,NY, NY 10016. If you are aware
34、of alternative suppliers, please provide thisinformation to ASTM International Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical committee,1whichyou may attend.D34520628.3 Some rubbers produce very characteristic hydrocarbonsand their identificat
35、ion is relatively easy. Examples of this typeare:8.3.1 Polyisoprene rubbers, which yield mainly isopreneand dipentene.8.3.2 Butadiene-styrene copolymers, which yield mainlybutadiene, vinyl cyclohexene, and styrene.8.3.3 Polybutadiene rubbers, which yield mainly butadieneand vinyl cyclohexene.8.3.4 I
36、sobutene-isoprene copolymers, which yield mainlyisobutylene.8.4 Some rubbers do not yield very characteristic hydrocar-bons. Careful inspection of the pyrogram is required. Supple-mentary tests, such as those for halogen and nitrogen may bean aid to more definite identification.8.5 It is recommended
37、 that, in addition to maintaining alibrary of pyrograms, the analyst compare the unknown samplewith a known, which appears most like his unknown, at thetime of analysis. In this manner, slight variations in operatingparameters, which might influence the pyrogram, might beavoided.9. Precision and Bia
38、s9.1 No statement is made about either precision or bias forPractice D 3452 since this practice is intended primarily for theidentification of polymers and their relative ratios and not theabsolute levels of the polymers in the compounds beingstudied.PART 2. IDENTIFICATION OF BLENDS OF POLYMERS10. S
39、cope10.1 This practice is a guide to the identification of blendsof rubbers in the raw, vulcanized, and unvulcanized state by thegas chromatographic patterns of pyrolysis products (pyro-grams). Implementation of this guide presupposes a workingknowledge of the principles and techniques of gas chroma
40、tog-raphy, sufficient to carry out the practice, as written, and tointerpret the results correctly.10.2 Two methods are described, depending upon the natureof the blend.10.2.1 Method AThis method is used when styrene-butadiene copolymers are absent. The absence of the styrenepeak, in a preliminary p
41、yrogram, indicates this type of blend.Method A will identify blends of the following:10.2.1.1 Polyisoprene of natural or synthetic origin,10.2.1.2 Butadiene,10.2.1.3 Isobutene-isoprene copolymers, and10.2.1.4 Halogenated isobutene-isoprene rubbers.10.2.2 Method BThis method is used when butadiene-st
42、yrene copolymers are present. The presence of the styrenepeak, in a preliminary pyrogram, indicates this type of blend.The method fails if other styrene polymers or copolymers orunextractable styrene-containing resins are present. Method Bis particularly suitable for the identification of polybutadi
43、ene inblends with styrene-butadiene copolymers. If the presence ofpolybutadiene in the unknown rubber can be excluded, useMethod A. Method B will identify butadiene-styrene copoly-mers with blends of the following:10.2.2.1 Polyisoprene of natural or synthetic origin,10.2.2.2 Butadiene, and10.2.2.3 I
44、sobutene-isoprene copolymers and halogenatedisobutene-isoprene rubbers.10.3 Methods A and B will not differentiate the following inblends:10.3.1 Natural polyisoprene from synthetic polyisoprene,10.3.2 Polybutadiene containing different microstruc-tures,10.3.3 Isobutene-isoprene copolymers and their
45、related ha-logenated rubbers, and10.3.4 Styrene-butadiene copolymers with different mono-mer ratios or different microstructures.11. Referenced Document11.1 See Section 2.12. Significance and Use12.1 See Section 3.13. Principle of the Practice13.1 See Section 4 in addition to the following:13.1.1 Me
46、thod AThis method is based upon the identifi-cation of the characteristic hydrocarbon in the pyrogram of theunknown rubber. The identification of the characteristic hydro-carbon is achieved by comparison of retention times under thesame chromatographic conditions for a known rubber as for anunknown
47、rubber. These retention times can be obtained frompyrograms of known rubbers or by direct injection of the purehydrocarbon into the chromatograph.13.1.2 Method BThis method is based upon the identifi-cation of the peaks of vinylcyclohexene and styrene and theirretention times, as in Method A. Identi
48、fication of the butadienepeaks is useful but not strictly necessary.13.2 The success of Method A or B depends upon examin-ing the unknown rubber under exactly the same gas chromato-graphic conditions as were used for preparation of the calibra-tion tables of Section 16.14. Apparatus14.1 See Section
49、5 in addition to the following:14.1.1 All the devices in accordance with 5.1 may be usedin Part 2, but the Curie point device is especially recommendedwhen Method B is used.14.2 See 5.2. Dual-column operation and temperature pro-gramming is strongly recommended, especially when MethodB is used. Some means of integration is strongly recommendedbut not mandatory.14.3 See 5.4. Nitrogen is the preferred carrier gas when theCurie point device is used. It should not be used with a thermalconductivity detector.D345206315. Procedure15.1 Sections 6 and 7 appl
