1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 7270-2:2012Rubber Analysis by pyrolyticgas-chromatographic methodsPart 2: Determination of styrene/butadiene/isoprene ratioBS ISO 7270-2:2012 BRITISH STANDARDNational fore
2、wordThis British Standard is the UK implementation of ISO 7270-2:2012. Itsupersedes BS ISO 7270-2:2005 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee PRI/23, Test methods for rubber and non-blackcompounding ingredients.A list of organizations represent
3、ed on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2012. Published by BSI StandardsLimited 2012ISBN 978 0 580 65977
4、 5ICS 83.060Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 October 2012.Amendments issued since publicationDate Text affectedBS ISO 7270-2:2012 ISO 2012Rubber
5、Analysis by pyrolytic gas-chromatographic methods Part 2: Determination of styrene/butadiene/isoprene ratioCaoutchouc Mthodes danalyse par pyrolyse et chromatographie en phase gazeuse Partie 2: Dtermination du rapport styrne/butadine/isoprneINTERNATIONAL STANDARDISO7270-2Second edition2012-09-15Refe
6、rence numberISO 7270-2:2012(E)BS ISO 7270-2:2012ISO 7270-2:2012(E)ii ISO 2012 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2012All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, incl
7、uding photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in
8、SwitzerlandBS ISO 7270-2:2012ISO 7270-2:2012(E) ISO 2012 All rights reserved iiiContents PageForeword iv1 Scope 12 Normative references . 13 Principle . 14 Reagents 15 Apparatus 25.1 Extraction apparatus 25.2 Pyrolysis/gas chromatography system . 26 Procedure 36.1 Preparation of test samples from ca
9、libration samples and unknown sample . 36.2 Test conditions . 36.3 Preparation of calibration curves . 66.4 Analysis of the unknown sample 77 Expression of results . 88 Precision 89 Test report . 8Annex A (informative) Precision . 9Bibliography . 11BS ISO 7270-2:2012ISO 7270-2:2012(E)ForewordISO (th
10、e International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committ
11、ee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechn
12、ical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bo
13、dies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any
14、 or all such patent rights.ISO 7270-2 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 2, Testing and analysis.This second edition cancels and replaces the first edition (ISO 7270-2:2005), which has been technically revised.ISO 7270 consists of the following
15、 parts, under the general title Rubber Analysis by pyrolytic gas-chromatographic methods: Part 1: Identification of polymers (single polymers and polymer blends) Part 2: Determination of styrene/butadiene/isoprene ratioiv ISO 2012 All rights reservedBS ISO 7270-2:2012INTERNATIONAL STANDARD ISO 7270-
16、2:2012(E)Rubber Analysis by pyrolytic gas-chromatographic methods Part 2: Determination of styrene/butadiene/isoprene ratioWARNING Persons using this part of ISO 7270 should be familiar with normal laboratory practice. This part of ISO 7270 does not purport to address all of the safety problems, if
17、any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.CAUTION Certain procedures specified in this part of ISO 7270 might involve the use or generation of substances, or
18、 the generation of waste, that could constitute a local environmental hazard. Reference should be made to appropriate documentation on safe handling and disposal after use.1 ScopeThis part of ISO 7270 specifies a pyrolytic gas-chromatographic method for the determination of the styrene/butadiene/iso
19、prene ratio in copolymers, or blends of homopolymers and/or copolymers, in raw rubbers or in unvulcanized or vulcanized compounds. It is applicable to copolymers/terpolymers consisting of styrene, butadiene and isoprene, and blends of these polymers.NOTE 1 The use of this part of ISO 7270 pre-suppos
20、es sufficient working knowledge of the principles and techniques of gas chromatography for the analyst to perform the operations described and interpret the results correctly.NOTE 2 The styrene/butadiene/isoprene ratio determined by this test method is affected by the presence of resin and by a high
21、 level of sulfur.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 1407:20
22、11, Rubber Determination of solvent extract3 PrincipleCalibration curves are first prepared by pyrolysing samples with known styrene/butadiene/isoprene ratios and analysing the pyrolysis products by gas chromatography to determine the percentage content of each component (styrene, butadiene and isop
23、rene), relative to the total of the three components.Samples of unknown composition are then pyrolysed, and the pyrolysis products are analysed under the same conditions. The styrene/butadiene/isoprene ratio in these samples is determined from the calibration curves.4 ReagentsAll reagents shall be o
24、f analytical grade.4.1 Solvents for extraction purposes.The following solvents are suitable: acetone; ISO 2012 All rights reserved 1BS ISO 7270-2:2012ISO 7270-2:2012(E) methanol; methylethylketone.4.2 Carrier gas: nitrogen;or helium.4.3 Gas for flame-ionization detector: hydrogen plus purified compr
25、essed air.5 Apparatus5.1 Extraction apparatusAs specified in ISO 1407.5.2 Pyrolysis/gas chromatography system5.2.1 GeneralThe apparatus utilized to obtain pyrograms consists of four parts: the pyrolysis device, the gas chromatograph, the gas-chromatographic column and the data-handling equipment.5.2
26、.2 Pyrolysis deviceThe following types of pyrolysis device are suitable: micro-furnace pyrolyser; Curie-point pyrolyser; platinum-filament pyrolyser.5.2.3 Gas chromatographA wide variety of gas chromatographs using either a flame-ionization detector (FID) or a thermal-conductivity detector (TCD) are
27、 suitable for use in this part of ISO 7270. An FID is preferable for use with capillary columns.5.2.4 Chromatographic columnsA variety of column materials, column lengths, column diameters and stationary and liquid phases are suitable for use in this part of ISO 7270, the main requirement being high
28、 resolution of the volatile pyrolysis products styrene, butadiene and isoprene.NOTE 1 Capillary columns, which have a separation efficiency which is better than that of packed columns, are suitable, but not essential.NOTE 2 Capillary columns containing non-polar polydimethylsiloxanes and partially m
29、odified (diphenyl-, cyanopropylphenyl- or other) semi-polar silicones are suitable.NOTE 3 When using an ordinary (30 m) capillary column, it is difficult to separate isobutene from butadiene completely. The reason is that, in pyrolytic gas-chromatographic methods, isobutene, which is a decomposition
30、 product of rubber containing the isoprene unit, is detected close to the retention time of butadiene. It is possible, however, to discriminate between isoprene and butadiene, even without complete separation, by means of the calibration curves.2 ISO 2012 All rights reservedBS ISO 7270-2:2012ISO 727
31、0-2:2012(E)5.2.5 Data-handling equipmentA recorder, an integrator or a computer data-analysis system may be used.6 Procedure6.1 Preparation of test samples from calibration samples and unknown sample6.1.1 A minimum of three calibration samples shall be used for the preparation of the calibration cur
32、ves, including a calibration sample with the composition expected for the unknown sample under test.6.1.2 The nature (raw, unvulcanized, or vulcanized) of the calibration samples should preferably be the same as that of the unknown sample under test.6.1.3 Process or extender oil and additives in bot
33、h the calibration samples and the unknown sample shall be extracted in accordance with ISO 1407:2011, method B, using a solvent suitable for the type of compound concerned (vulcanized or unvulcanized). The solvent chosen shall not affect the polymer and shall remove as much of the process and extend
34、er oil and additives as possible. All samples shall be dried after extraction, using the drying procedure specified in method B of ISO 1407:2011.NOTE Process and extender oils can cause serious interference.6.1.4 From the extracted samples, take test samples of masses appropriate to the pyrolyser us
35、ed, and as small and as equal as possible for improved reproducibility.NOTE Generally, the mass will be between 0,1 mg and 5 mg, depending on the pyrolyser.6.2 Test conditions6.2.1 The test conditions, including the pyrolysis temperature, shall be the same for the preparation of the calibration curv
36、es and the analysis of the unkown sample.6.2.2 An appropriate pyrolysis temperature is 500 C to 600 C for a micro-furnace or Curie-point pyrolyser, and 600 C to 750 C for a platinum-filament pyrolyser.6.2.3 The gas-chromatographic conditions will depend on the column used. Typical operating conditio
37、ns are given in Tables 1 to 3, and examples of chromatograms obtained using each set of conditions are given in Figures 1 to 3. ISO 2012 All rights reserved 3BS ISO 7270-2:2012ISO 7270-2:2012(E)Table 1 Recommended operating conditions for micro-furnace pyrolysis followed by chromatography with a 30
38、m capillary columnPyrolysisDevicePyrolysis temperatureMicro-furnace550 CGas-chromatographic columnLiquid phaseFilm thicknessColumn diameter/materialColumn length5 % diphenyldimethylpolysiloxane1,0 m0,25 mm ID/stainless steel (deactivated)30 mChromatographic conditionsCarrier gas and flow rateInjecto
39、r temperatureType of detectorDetector temperatureHelium, 0,8 ml/min250 CFID300 CTemperature programme Isothermal for 2 min at 50 Cthen increase at 20 C/min from 50 C to 280 Cthen isothermal for 10 min at 280 CTable 2 Recommended operating conditions for micro-furnace pyrolysis followed by chromatogr
40、aphy with a 60 m capillary columnPyrolysisDevicePyrolysis temperatureMicro-furnace550 CGas-chromatographic columnLiquid phaseFilm thicknessColumn diameter/materialColumn length5 % diphenyldimethylpolysiloxane1,0 m0,25 mm ID/stainless steel (deactivated)60 mChromatographic conditionsCarrier gas and f
41、low rateInjector temperatureType of detectorDetector temperatureHelium, 0,8 ml/min250 CFID300 CTemperature programme Isothermal for 7 min at 50 Cthen increase at 10 C/min from 50 C to 280 Cthen isothermal for 10 min at 280 C4 ISO 2012 All rights reservedBS ISO 7270-2:2012ISO 7270-2:2012(E)Table 3 Re
42、commended operating conditions for Curie-point pyrolysis followed by chromatography with a packed columnPyrolysisDevicePyrolysis temperature/timeCurie-point pyrolyser590 C/3 sGas-chromatographic columnLiquid phaseColumn diameter/materialColumn length20 % silicone 710/Chromosorb W (60 to 80 mesh)3 mm
43、 ID/stainless steel3 mChromatographic conditionsCarrier gasType of detectorHeliumFIDTemperature programme Isothermal for 2 min at 50 Cthen increase at 10 C/min from 50 C to 220 Cthen isothermal for 10 min at 220 C4 6 8 10 12 14 1612310 2 18XKeyX time (min)1 butadiene2 isoprene3 styreneFigure 1 Examp
44、le of chromatogram obtained with 30 m capillary column ISO 2012 All rights reserved 5BS ISO 7270-2:2012ISO 7270-2:2012(E)2 4 6 8 10 12 14 16 18 20 22 24 26 281123XKeyX time (min)1 butadiene2 isoprene3 styreneFigure 2 Example of chromatogram obtained with 60 m capillary column412381216202428XKeyX tim
45、e (min)1 butadiene2 isoprene3 styreneFigure 3 Example of chromatogram obtained with packed column6.3 Preparation of calibration curves6.3.1 Place a test sample taken from one of the extracted calibration samples in the pyrolysis device, pyrolyse it, and analyse the pyrolysis products with the gas ch
46、romatograph to obtain the pyrogram. Repeat this step for the other calibration samples in order to prepare the calibration curves.6 ISO 2012 All rights reservedBS ISO 7270-2:2012ISO 7270-2:2012(E)6.3.2 Record the peak areas PST, PBDand PIPfor styrene, butadiene and isoprene, respectively, obtained f
47、rom the data-handling equipment (5.2.5). Calculate the percentage peak area for each of these components, AST, ABDand AIP, relative to their total, as follows:APPPPSTSTST BD IP=+100APPPPBDBDST BD IP=+100APPPPIPIPST BD IP=+100whereASTis the percentage peak area for styrene;ABDis the percentage peak a
48、rea for butadiene;AIPis the percentage peak area for isoprene;PSTis the peak area for styrene;PBDis the peak area for butadiene;PIPis the peak area for isoprene.6.3.3 For each of the three components, styrene, butadiene and isoprene, prepare a calibration curve. For styrene, for example, plot the kn
49、own percentage of styrene (relative to the total of the three) on the X-axis against the percentage peak area obtained for styrene in the pyrolysis products on the Y-axis. Prepare a regression line for styrene by the least-squares method, and obtain the slope a and Y-intercept b. Using the same procedure, prepare the calibration curves for butadiene and isoprene, and obtain the slopes (c and e) and Y-intercepts (d and f).6.4 Analysis of the unknown sample6.4.1 Pyrolyse a tes
