1、BSI Standards PublicationBS ISO 21048:2014Plastics Epoxy resins Determination of 1,2-glycolcontentBS ISO 21048:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 21048:2014. Itsupersedes BS ISO 21048:2004 which is withdrawn.The UK participation in its prepara
2、tion was entrusted to TechnicalCommittee PRI/42, Fibre reinforced thermosetting plastics andprepregs.A list of organizations represented 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 resp
3、onsible for its correctapplication. The British Standards Institution 2014. Published by BSI StandardsLimited 2014ISBN 978 0 580 81810 3ICS 83.080.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards
4、 Policy and Strategy Committee on 31 March 2014.Amendments issued since publicationDate Text affectedBS ISO 21048:2014 ISO 2014Plastics Epoxy resins Determination of 1,2-glycol contentPlastiques Rsines poxydes Dtermination de la teneur en 1,2-glycolINTERNATIONAL STANDARDISO21048Second edition2014-02
5、-15Reference numberISO 21048:2014(E)BS ISO 21048:2014ISO 21048:2014(E)ii ISO 2014 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2014All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or me
6、chanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested 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
7、 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 21048:2014ISO 21048:2014(E) ISO 2014 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 15 Reagents 26 Apparatus . 47 Proce
8、dure. 48 Expression of results 59 Precision . 510 Test report . 6BS ISO 21048:2014ISO 21048:2014(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally ca
9、rried 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 part in the work
10、. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the differ
11、ent approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may
12、be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents
13、).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles
14、in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information.The committee responsible for this document is ISO/TC 61, Plastics, Subcommittee SC 12, Thermosetting materials.This second edition cancels and replaces the first edition (ISO 21048:2004), which has
15、been technically revised.iv ISO 2014 All rights reservedBS ISO 21048:2014ISO 21048:2014(E)IntroductionIn producing epoxy resin based on epichlorohydrin, impurities containing 1,2-glycol may be formed. Owing to the hydrophilic characteristics of 1,2-glycol, it is necessary to control the level of the
16、se impurities, since they could affect final properties such as electrical insulation. Additionally, these impurities could affect the speed of the curing reaction when using curing agents such as amines and acid anhydrides. Therefore, it is important to determine the 1,2-glycol content in epoxy res
17、ins for both resin manufacture and customer use. ISO 2014 All rights reserved vBS ISO 21048:2014BS ISO 21048:2014Plastics Epoxy resins Determination of 1,2-glycol contentSAFETY STATEMENT Persons using this document should be familiar with normal laboratory practice, if applicable. This document does
18、 not purport to address all of the safety concerns, 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 regulatory requirements.1 ScopeThis International Standard specifies a method for the deter
19、mination of the 1,2-glycol content in epoxy resins.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest editi
20、on of the referenced document (including any amendments) applies.ISO 3696, Water for analytical laboratory use Specification and test methodsISO 5725-2, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic method for the determination of repeatability and reproducibilit
21、y of a standard measurement method3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.11,2-glycolthe 1,2-glycol group -CH(OH)CH2OH in epoxy resins, the content of which is expressed in moles per kilogram of the epoxy resinNote 1 to entry: This moiety
22、 is chemically equivalent to two OH groups.Note 2 to entry: Other possible nomenclatures are vicinal-OH group, 1,2-dihydroxyl group, -glycol group.4 Principle1,2-glycol is determined on the basis of the following reactions.1,2-glycol is oxidized to aldehyde compounds by an excess of orthoperiodic ac
23、id (reaction 1), then potassium iodide is added to the reaction mixture in the presence of sulfuric acid (reaction 2). The generated iodine is then titrated by standardized sodium thiosulfate solution (reaction 3). The 1,2-glycol content is calculated from the sodium thiosulfate consumption.INTERNAT
24、IONAL STANDARD ISO 21048:2014(E) ISO 2014 All rights reserved 1BS ISO 21048:2014ISO 21048:2014(E)Reaction 1Reaction 2 HIO4+ 4H2SO4+ 7KI 3K2SO4+ KHSO4+ 4H2O + 4I2HIO3+ 3H2SO4+ 5KI 2K2SO4+ KHSO4+ 3H2O + 3I2Reaction 3 I2+ 2Na2S2O3 2NaI + Na2S4O65 ReagentsUse reagents of recognized analytical grade, and
25、 water of grade 3 (as defined in ISO 3696) or better.5.1 Chloroform.WARNING Chloroform is toxic. Avoid inhalation of its vapour. Prevent skin and eye contact. Work in a fume hood or in a well ventilated area. The threshold limit is 10 g/g.5.2 Methanol.WARNING Methanol is toxic. Avoid inhalation of i
26、ts vapour. Prevent skin and eye contact. Work in a fume hood or in a well ventilated area. The threshold limit is 200 g/g.5.3 Benzyltrimethylammonium hydroxide, 40 % (by mass) solution in methanol.5.4 Acetic acid.5.5 Orthoperiodic acid.5.6 Orthoperiodic acid, 0,2 mol/l solution.5.6.1 PreparationWeig
27、h 2,70 g to 2,75 g of orthoperiodic acid into a 500 ml beaker (6.7) and dissolve in 450 ml of methanol (5.2), mixing with a magnetic stirrer (6.2). Place the pH electrode (6.3) into the solution. Neutralize the solution to pH 7,0 by adding benzyltrimethylammonium hydroxide solution (5.3) slowly with
28、 stirring. Add 15 ml of acetic acid (5.4) and 5 ml of water, using a 20 ml graduated glass cylinder (6.8), and, using a 500 ml volumetric flask (6.9), fill to the mark with methanol.5.7 Sulfuric acid, 10 % (by mass) solution.Add 10 g of sulfuric acid dropwise to 90 g of water with stirring.5.8 Potas
29、sium iodide, 20 % (by mass) solution.Dissolve 20 g of potassium iodide in 80 g of water.5.9 Anhydrous sodium carbonate.2 ISO 2014 All rights reservedBS ISO 21048:2014ISO 21048:2014(E)5.10 Potassium iodate.5.11 Oxygen-free water.5.11.1 PreparationPut grade 3 water (as specified in ISO 3696) into the
30、conical flask (6.5), boil it for about 5 min to expel dissolved oxygen and allow it to cool to room temperature by sealing with nitrogen gas. Alternatively, it is permissible to expel dissolved oxygen by sparging high purity nitrogen gas for about 15 min.5.12 Sodium thiosulfate, 0,1 mol/l solution.5
31、.12.1 PreparationWeigh out 26,0 g of sodium thiosulfate 5-hydrate and 0,20 g of anhydrous sodium carbonate (5.9). Add 1 l of oxygen-free water (5.11) and store in an airtight container. Allow to stand for two days before using.5.12.2 StandardizationHeat the required amount of potassium iodate (refer
32、ence material for volumetric analysis) (5.10) at 130 C for about 2 h, and allow it to cool in a desiccator. Weigh 0,9 g to 1,1 g of the dried KIO3to the nearest 0,1 mg into a 250 ml volumetric flask (6.9), dissolve in water and fill to the mark with water. Using a pipette, place 25 ml of the solutio
33、n in a 300 ml conical flask (6.5). Add 2 g of potassium iodide and 2 ml of sulfuric acid (1 + 1) to the conical flask, stopper immediately, shake gently, and allow to stand for 5 min in the dark. As an indicator, add 0,5 ml of starch solution (5.13), and titrate with 0,1 mol/l sodium thiosulfate sol
34、ution (5.12). Add another 0,5 ml of the starch solution when nearing the end point. Continue to titrate until the blue colour of the solution just disappears.Separately, measure 25 ml of water (using a pipette) and 2 g of potassium iodide into a 300 ml conical flask (6.5), then add 2 ml of sulfuric
35、acid (1 + 1), stopper immediately, shake gently, and allow to stand for 5 min in the dark. Carry out a blank titration by the same procedure as described, and use the result to correct the volume needed for the standardization titration.5.12.3 Calculation of concentrationCalculate the concentration
36、from the following equation:capVV=()0 00356671000021,(1)wherec is the concentration of the sodium thiosulfate solution, expressed in moles per litre;a is the mass of potassium iodate, expressed in grams;p is the purity of the potassium iodate, expressed in percent;0,003 566 7 is the mass of potassiu
37、m iodate equivalent to 1 ml of 0,1 mol/l sodium thiosulfate solution;V1is the volume of sodium thiosulfate solution used in the titration, expressed in mil-lilitres;V2is the volume of sodium thiosulfate solution used in the blank titration, expressed in millilitres. ISO 2014 All rights reserved 3BS
38、ISO 21048:2014ISO 21048:2014(E)Round the result to three significant figures.5.13 Starch solution, 1 % (by mass).Dissolve 1 g of water-soluble starch in 99 g of hot water.6 ApparatusUsual laboratory apparatus, plus the following.6.1 Analytical balance, accurate to 0,1 mg.6.2 Magnetic stirrer, equipp
39、ed with a polytetrafluoroethylene-coated bar.6.3 pH-meter, accurate to 0,1 pH-units, calibrated in advance, equipped with a glass combination electrode and electrode stand.6.4 Burette, 50 ml.6.5 Conical flask, 300 ml, with a ground-glass stopper.6.6 Pipettes, 5 ml, 20 ml and 25 ml.6.7 Beaker, 500 ml
40、.6.8 Graduated glass cylinders, 20 ml and 100 ml.6.9 Volumetric flasks, 250 ml and 500 ml.7 Procedure7.1 Select the mass of the test portion in accordance with the expected 1,2-glycol content (see Table 1).Table 1 Mass of test portion1,2-glycol content, wmol/kgMass of test portiongw 0,010,01 w 0,050
41、,05 w 0,10,1 w 0,20,2 w1084217.2 Weigh the test portion to the nearest 0,1 mg into a 300 ml conical flask (6.5). Add 25 ml of chloroform (5.1) and warm the mixture to obtain a clear solution. Then cool to ambient temperature.7.3 Using a pipette, add 25 ml of 0,2 mol/l orthoperiodic acid solution (5.
42、6) to the conical flask. Wet a ground-glass stopper with water and stopper the conical flask tightly. Mix well and allow the reaction mixture to stand at room temperature for 2 h.4 ISO 2014 All rights reservedBS ISO 21048:2014ISO 21048:2014(E)7.4 Add 100 ml of cold water to the conical flask and the
43、n stopper again. Mix vigorously, using a magnetic stirrer, for 30 s.7.5 Wash the inside of the conical flask and the glass stopper with a small quantity of water. Using a pipette, add 5 ml of 10 % sulfuric acid solution (5.7).7.6 Using a pipette, add 20 ml of 20 % potassium iodide solution (5.8).7.7
44、 Mix well for 30 s with a magnetic stirrer. Titrate with 0,1 mol/l sodium thiosulfate solution (5.12), with stirring. As an indicator, add about 1 ml of starch solution (5.13) when the colour of the solution becomes pale yellow which shows the end point is near.7.8 Continue to titrate until the blue
45、 colour of the solution just disappears.7.9 Carry out a blank test, following the same procedure and using the same reagents, but omitting the test portion.8 Expression of resultsCalculate the 1,2-glycol content of the sample from the following equation:wVV cm=()2102(2)wherew is the 1,2-glycol conte
46、nt of the sample, expressed in moles per kilogram;m0is the mass of the test portion, expressed in grams;V1is the volume of sodium thiosulfate solution used in the titration of the test portion, expressed in millilitres;V2is the volume of sodium thiosulfate solution used in the blank titration, expre
47、ssed in millili-tres;c is the concentration of the sodium thiosulfate solution, expressed in moles per litre.9 PrecisionPrecision data were determined from a round-robin experiment organized in January 2000 involving eight laboratories in Japan. Three commercial epoxy resins with different levels of
48、 1,2-glycol content were tested and the results were analysed in accordance with ISO 5725-2.The repeatability and reproducibility calculated from the experiments are given in Table 2. ISO 2014 All rights reserved 5BS ISO 21048:2014ISO 21048:2014(E)Table 2 Precision dataSample 1,2-glycol content (ave
49、raged)mol/kgRepeatabilitysrReproducibilitysRSample A (liquid BPA type epoxy resin)0,029 0,002 0,003Sample B (liquid BPA type epoxy resin)0,063 0,002 0,002Sample C (solid BPA type epoxy resin)0,24 0,02 0,0210 Test reportThe test report shall include the following:a) a reference to this International Standard;b) all details necessary for identification of the sample;c) the test result;d) the date of the test;e) any other relevant information.6 ISO 2014 All rights reservedBS ISO 21048:2014BS ISO 210
