1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 248-2:2012Rubber, raw Determinationof volatile-matter contentPart 2: Thermogravimetric methods usingan automatic analyser with an infrareddrying unitBS ISO 248-2:2012 BRIT
2、ISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 248-2:2012.The UK participation in its preparation was entrusted to TechnicalCommittee PRI/23, Test methods for rubber and non-blackcompounding ingredients.A list of organizations represented on this committee can beo
3、btained 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 65976 8ICS 83.040.10Compliance wi
4、th a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 August 2012.Amendments issued since publicationDate Text affectedBS ISO 248-2:2012 ISO 2012Rubber, raw Determination of volat
5、ile-matter content Part 2: Thermogravimetric methods using an automatic analyser with an infrared drying unitCaoutchouc brut Dtermination des matires volatiles Partie 2: Mthodes thermogravimtriques utilisant un analyseur automatique avec une unit de schage infrarougeINTERNATIONAL STANDARDISO248-2Fir
6、st edition2012-05-01Reference numberISO 248-2:2012(E)BS ISO 248-2:2012ISO 248-2:2012(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, electroni
7、c or mechanical, including 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
8、.iso.orgPublished in SwitzerlandBS ISO 248-2:2012ISO 248-2:2012(E) ISO 2012 All rights reserved iiiContents PageForeword iv1 Scope 12 Normative references . 13 Principle . 14 Reagents 25 Apparatus 25.1 Automatic analyser . 26 Sampling and preparation of test portion . 27 Procedure 27.1 General . 27.
9、2 Determination of end points for method A and method B . 37.3 Method A (pre-defined drying time method) 47.4 Method B (in which drying ends when the mass loss rate has decreased to a pre-defined level) 57.5 Calculation of volatile-matter content . 58 Precision 59 Test report . 5Annex A (informative
10、) Examples of test conditions 7Annex B (informative) Precision . 8Bibliography .10BS ISO 248-2:2012ISO 248-2:2012(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standar
11、ds is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take
12、 part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical 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
13、 prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies 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 th
14、at some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 248-2 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 2, Testing and analysis.ISO 248 consists
15、of the following parts, under the general title Rubber, raw Determination of volatile-matter content: Part 1: Hot-mill method and oven method Part 2: Thermogravimetric methods using an automatic analyser with an infrared drying unitiv ISO 2012 All rights reservedBS ISO 248-2:2012INTERNATIONAL STANDA
16、RD ISO 248-2:2012(E)Rubber, raw Determination of volatile-matter content Part 2: Thermogravimetric methods using an automatic analyser with an infrared drying unitWARNING Persons using this part of ISO 248 should be familiar with normal laboratory practice. This part of ISO 248 does not purport to a
17、ddress all of the safety problems, if 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 248 could involve th
18、e use or generation of substances, or 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 Scope1.1 This part of ISO 248 specifies two thermogravimetric methods for the determinati
19、on of moisture and other volatile-matter content in raw rubbers by using an automatic analyser with an infrared drying unit.1.2 These methods are applicable to the determination of volatile-matter content in synthetic rubbers (SBR, NBR, BR, IR, CR, IIR, halogenated IIR and EPDM) listed in ISO 1629 a
20、nd to various forms of raw rubber, such as bale, block, chip, pellet, crumb, powder and sheet. These methods might also be applicable to other raw rubbers, but in such cases it is necessary to prove that the change in mass is due solely to loss of original volatile matter and not to rubber degradati
21、on.1.3 The methods are not applicable to raw rubbers which need homogenizing as specified in ISO 1795.1.4 The hot-mill method and the oven method specified in ISO 248-1 and the methods specified in this part of ISO 248 might not give identical results. In cases of dispute, therefore, the oven method
22、, procedure A, specified in ISO 248-1:2011 shall be the referee method.NOTE These methods can be useful for routine determinations, e.g. quality control, when the measurement conditions for the automatic analyser are fixed for a particular raw rubber or grade of raw rubber.2 Normative referencesThe
23、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 248-1:2011, Rubber, raw Determination of volatile-
24、matter content Part 1: Hot-mill method and oven methodISO 1629, Rubber and latices NomenclatureISO 1795, Rubber, raw natural and raw synthetic Sampling and further preparative procedures3 PrincipleA test portion is continuously weighed to constant mass by a thermogravimetric method using an automati
25、c analyser with infrared drying. The volatile-matter content is calculated as the mass lost during this procedure. ISO 2012 All rights reserved 1BS ISO 248-2:2012ISO 248-2:2012(E)4 Reagents4.1 Sodium l-tartrate dihydrate, purity 99 %, for use as a standard reference material.5 Apparatus5.1 Automatic
26、 analyser5.1.1 GeneralThe automatic analyser shall consist of the following components:a) an infrared drying unit or a far-infrared drying unit or a near-infrared drying unit;b) a balance, capable of weighing to the nearest 1 mg;c) a microprocessor, capable of controlling drying conditions such as t
27、he temperature and the drying end point, and of continuously calculating volatile-matter content as the mass lost during drying.5.1.2 Performance requirementsThe accuracy of the system shall be demonstrated by performing 10 successive determinations on the standard reference material sodium l-tartra
28、te dihydrate. The mean of the 10 determinations shall be (15,66 0,5) %. The relative standard deviation, obtained by the following equation, shall be less than 1,0 %.Relative standard deviation (%) =sw100wheres is the standard deviation;w is the mean volatile-matter content, in mass %.6 Sampling and
29、 preparation of test portionTake a laboratory sample in accordance with the method specified in ISO 1795, and then prepare a test portion of between 2 g and 15 g from the laboratory sample. The actual mass of the test portion will depend on the type of analyser, the expected volatile-matter content,
30、 and the form of the sample. For raw rubbers in bale form, the test portion shall be cut into small pieces of volume less than about 350 mm3(in the ideal case of a cubic piece, the length of a side should be about 7 mm). This operation shall be carried out as quickly as possible so as not to lose vo
31、latile matter.The test result is taken to be the value from a single determination of the volatile-matter content.7 Procedure7.1 GeneralEither method A (which uses a pre-defined drying time) or method B (in which drying ends when the mass loss rate has decreased to a pre-defined level) can be chosen
32、, provided the automatic analyser used offers the choice. The end point (the pre-defined drying time for method A or the pre-defined mass loss rate for method B) shall be determined for each of the two methods for each type or grade of rubber to be analysed.2 ISO 2012 All rights reservedBS ISO 248-2
33、:2012ISO 248-2:2012(E)7.2 Determination of end points for method A and method B7.2.1 First take a typical sample of the type or grade of rubber being analysed and determine its volatile-matter content in accordance with one of the methods described in ISO 248-1.7.2.2 Then, for method A, take a test
34、portion of between 2 g and 15 g and weigh it to the nearest 1 mg. Operating the automatic analyser in accordance with the manufacturers instructions, set a drying temperature (preferably between 100 C and 120 C) and obtain a drying profile (X-axis: time in min, Y-axis: volatile matter lost, in %). F
35、rom the drying profile (see Figure 1), determine the time at which the volatile-matter content determined by the automatic analyser is equal to that determined in 7.2.1. Take this drying time as the pre-defined drying time to be used in method A for this particular type or grade of rubber.7.2.3 For
36、method B, take a test portion of between 2 g and 15 g and weigh it to the nearest 1 mg. Operating the automatic analyser in accordance with the manufacturers instructions, set a drying temperature (preferably between 100 C and 120 C) and obtain a drying profile (X-axis: time, Y-axis: mass). From the
37、 drying profile (see Figure 2), determine the mass loss rate at the point on the profile where the volatile-matter content corresponds to that determined in 7.2.1. Take this value of the mass loss rate as the end point for use in method B for this particular type or grade of rubber.NOTE The automati
38、c analyser can be programmed to calculate this value automatically.7.2.4 7.2.1 and either 7.2.2 or 7.2.3 shall be performed individually for each type or grade of raw rubber to be analysed.YX123KeyX time, minY volatile matter lost from test portion, %1 volatile-matter content determined using ISO 24
39、8-12 drying time3 drying end pointFigure 1 Drying profile and drying end point for method A ISO 2012 All rights reserved 3BS ISO 248-2:2012ISO 248-2:2012(E)YX1234KeyX timeY mass of test portion1 final (dry) mass of test portion when volatile-matter content is determined using ISO 248-12 mass loss in
40、crement, mg3 mass measurement interval, s4 drying end pointFigure 2 Drying profile and drying end point for method B7.3 Method A (pre-defined drying time method)7.3.1 Operate the apparatus in accordance with the manufacturers instructions. A general procedure is described in 7.3.2 to 7.3.7.7.3.2 Inp
41、ut the drying temperature and the pre-defined drying time determined in 7.2.2 into the microprocessor of the apparatus.7.3.3 Position an empty sample tray in the designated place and set the balance to zero.7.3.4 Take a test portion of about the same mass (within 10 %) as was taken to determine the
42、drying profile in 7.2.2, spread it on the sample tray as uniformly and quickly as possible and press the start button. The initial mass (mA) of the test portion before drying starts will be measured and recorded automatically. Drying will start immediately.7.3.5 When the drying time reaches the pre-
43、defined value, drying will stop automatically.7.3.6 The final mass (mB) of the test portion after drying will be measured and recorded automatically.7.3.7 The volatile-matter content will be calculated automatically in accordance with 7.5.4 ISO 2012 All rights reservedBS ISO 248-2:2012ISO 248-2:2012
44、(E)7.4 Method B (in which drying ends when the mass loss rate has decreased to a pre-defined level)7.4.1 Operate the apparatus in accordance with the manufacturers instructions. A general procedure is described in 7.4.2 to 7.4.8.7.4.2 Input the drying temperature and the pre-defined mass loss rate d
45、etermined in 7.2.3 into the microprocessor of the apparatus.7.4.3 Position an empty sample tray in the designated place and set the balance to zero.7.4.4 Take a test portion of about the same mass (within 10 %) as was taken to determine the drying profile in 7.2.3, spread it on the sample tray as un
46、iformly and quickly as possible and press the start button. The initial mass (mA) of the test portion before drying starts will be measured and recorded automatically. Drying will start immediately.7.4.5 The mass of the test portion is continuously measured and recorded during drying, and the mass l
47、oss rate continuously calculated.7.4.6 When the mass loss rate reaches the pre-defined value, drying will stop automatically.7.4.7 The final mass (mB) of the test portion after drying will be measured and recorded automatically.7.4.8 The volatile-matter content will be calculated automatically in ac
48、cordance with 7.5.7.5 Calculation of volatile-matter contentThe volatile-matter content is calculated as follows:wmmm=()ABA100wherew is the volatile-matter content, in mass %;mAis the mass of the test portion before drying, in g;mBis the mass of the test portion after drying, in g.8 PrecisionSee Ann
49、ex B.9 Test reportThe test report shall include the following particulars:a) full details of the sample of raw rubber tested;b) test method:1) a reference to this part of ISO 248,2) the method used (method A or method B),3) full details of the apparatus and measurement conditions, ISO 2012 All rights reserved 5BS ISO 248-2:2012ISO 248-2:2012(E)4) the method, and associated procedure, in ISO 248-1 used in determining the pre-defined drying time (method A) or pre-defined mass loss rate (method B);c) departu
