1、BSI Standards PublicationBS ISO 25761:2014Plastics Polyols for use in theproduction of polyurethanes Determination of basicity(total amine value), expressedas percent nitrogenBS ISO 25761:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 25761:2014. It super
2、sedes BS ISO 25761:2008 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee PRI/42, Fibre reinforced thermosetting plastics and prepregs.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does
3、 not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2014.Published by BSI Standards Limited 2014ISBN 978 0 580 81991 9ICS 83.080.10Compliance with a British Standard cannot confer immunity from legal
4、 obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 May 2014.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 25761:2014 ISO 2014Plastics Polyols for use in the production of polyurethanes Determina
5、tion of basicity (total amine value), expressed as percent nitrogenPlastiques Polyalcools utiliss pour la production de polyurthannes Dtermination de la basicit (valeur totale damines) en pourcentage dazoteINTERNATIONAL STANDARDISO25761Second edition2014-03-01Reference numberISO 25761:2014(E)BS ISO
6、25761:2014ISO 25761:2014(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 mechanical, including photocopying, or postin
7、g 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 11Fax + 41 22 749 09 47E-mail copyrightiso
8、.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 25761:2014ISO 25761:2014(E) ISO 2014 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 25 Sampling 26 Apparatus . 27 Interference . 28 Reagents 29 Procedure. 310 Exp
9、ression of results 411 Precision and bias . 411.1 General . 411.2 Precision . 511.3 Bias 512 Test report . 5Annex A (informative) Determination of the factor F for 0,1 mol/l perchloric acid in acetic acid 6Bibliography 7BS ISO 25761:2014ISO 25761:2014(E)ForewordISO (the International Organization fo
10、r 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 committee has been established has the
11、 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 electrotechnical standardization.The proced
12、ures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial
13、 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 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 id
14、entified 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).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanatio
15、n on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary information.The committee responsible for this document
16、is ISO/TC 61, Plastics, Subcommittee SC 12, Thermosetting materials.This second edition cancels and replaces the first edition (ISO 25761:2008), which has been technically revised.iv ISO 2014 All rights reservedBS ISO 25761:2014ISO 25761:2014(E)IntroductionPolyurethanes are produced by the catalysed
17、 reaction of isocyanates with polyols. The basicity of the polyol employed affects the rate of reaction and speed of cure of the product. It is therefore necessary to determine the basicity in order to predict reactivity and monitor product quality. ISO 2014 All rights reserved vBS ISO 25761:2014BS
18、ISO 25761:2014Plastics Polyols for use in the production of polyurethanes Determination of basicity (total amine value), expressed as percent nitrogenSAFETY STATEMENT Persons using this document should be familiar with normal laboratory practice, if applicable. This document does not purport to addr
19、ess 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 ScopeThe method specified in this International Standard measures the basic constitue
20、nts in polyols that are soluble in glacial acetic acid and reactive with perchloric acid. Samples containing 0,3 % to 10 % of nitrogen have been evaluated by this method. The method is applicable to amine-based polyols, polyether polyols and polyether polyol blends that are used in polyurethane reac
21、tions. The results are measures of batch-to-batch uniformity and may be used to estimate reactivity in polyurethane reactions.It is also permissible to express the results in equivalents of base per gram of sample.NOTE This method is technically equivalent to that in ASTM D 6979.2 Normative referenc
22、esThe 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 1042, Laboratory glassware One-mark volumetr
23、ic flasksISO 4788, Laboratory glassware Graduated measuring cylindersISO 3696, Water for analytical laboratory use Specification and test methodsISO 6353-1, Reagents for chemical analysis Part 1: General test methodsISO 6353-2, Reagents for chemical analysis Part 2: Specifications First seriesISO 63
24、53-3, Reagents for chemical analysis Part 3: Specifications Second series3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1polyolpolymer based on ethylene oxide and/or propylene oxide which contains two or more hydroxyl groups3.2polyurethanepolyme
25、r prepared by the reaction of an organic di- or polyisocyanate with a compound containing two or more hydroxyl groups3.3percent nitrogenquantity of perchloric-acid-titratable base in a sample, expressed as a mass percentage of nitrogenINTERNATIONAL STANDARD ISO 25761:2014(E) ISO 2014 All rights rese
26、rved 1BS ISO 25761:2014ISO 25761:2014(E)3.4alkalinityquantity of perchloric-acid-titratable base in a sample, expressed as mg of KOH/g of sample3.5total amine valuequantity of perchloric-acid-titratable base in a sample, identified only as amines and expressed as mg of KOH/g of sample4 PrincipleA te
27、st portion of the sample is dissolved in glacial acetic acid. The resulting single-phase solution is titrated at room temperature to a potentiometric end point with a standardized solution of perchloric acid in acetic acid. The result is reported as percent nitrogen or mg of KOH/g of sample.5 Sampli
28、ngDraw samples from a well-mixed vessel into a thoroughly cleaned and dry borosilicate-glass container (soft-glass containers are not acceptable). If sampling from a line or valve, flush the line thoroughly with the product before starting to draw the sample. Seal the sample until analysis.6 Apparat
29、us6.1 One-mark volumetric flask, of capacity 1 000 ml conforming to ISO 1042.6.2 Graduated measuring cylinder, of capacity 100 ml and 500 ml conforming to ISO 4788.6.3 Precision balance, accurate to 0,1 mg or better.6.4 Potentiometric titrator, capable of determining multiple end points, equipped wi
30、th a pair of electrodes or a combination glass calomel electrode, a 20 ml burette and a recorder.7 InterferenceAny acidic or basic materials inadvertently introduced into the sample will cause errors in the analysis. Any material capable of serving as a buffer may interfere with the analysis by obsc
31、uring the titration end point.8 ReagentsUnless otherwise indicated, it is intended that all reagents shall conform to the specifications of ISO 6353-1, ISO 6353-2 and ISO 6353-3, as applicable. Other grades may be used, however, provided that it is first determined that the reagent is of sufficientl
32、y high purity to permit its use without lessening the accuracy of the determination.Unless otherwise indicated, references to water shall be understood to mean grade 2 water as defined in ISO 3696.8.1 Glacial acetic acid.8.2 Acetic anhydride.8.3 Perchloric acid, nominal concentration 70 %.2 ISO 2014
33、 All rights reservedBS ISO 25761:2014ISO 25761:2014(E)8.4 Perchloric acid in acetic acid, concentration 0,10 mol/l.One way of preparing the 0,10 mol/l perchloric acid in acetic acid is as follows. In a 1 000 ml volumetric flask, mix 8,7 ml of perchloric acid (8.3) with 500 ml of glacial acetic acid
34、(8.1). Add 25 ml of acetic anhydride (8.2) and dilute to volume with glacial acetic acid.WARNING Perchloric acid is extremely irritating to the skin, eyes and mucous membranes, highly toxic via oral and inhalation routes, and can form explosive mixtures when mixed with carbonaceous material or allow
35、ed to dry. Concentrated perchloric acid should only be used in a hood approved for perchloric acid use. Chemically resistant gloves should be worn. In the event of skin contact, wash with soap and water. Goggles or safety glasses with side shields should be worn. In the event of eye contact, flush w
36、ith copious amounts of water for 15 min. In the event of inhalation, move the victim to an uncontaminated area. In the event of ingestion, do not induce vomiting. For all exposures, seek professional medical advice.It is strongly recommended that reference articles on perchloric acid safety be consu
37、lted to determine safe-handling and clean-up procedures (see References 1 to 6 and references cited therein).9 Procedure9.1 Weigh a test portion of the sample into a suitable container, calculating the mass of the test portion as follows:M = 2/P whereM is the mass of the test portion, in g;P is the
38、expected percent nitrogen content of the sample.For test portion masses below 10,0 g, record the mass to the nearest 0,1 mg; for test portion masses greater than 10,0 g, record the mass to the nearest 0,01 g.9.2 Add 100 ml of glacial acetic acid and stir gently until the test portion has dissolved c
39、ompletely.If necessary, the mixture can be heated gently until the test portion has completely dissolved.9.3 Titrate the test solution potentiometrically using a potentiometric titrator (6.4) with 0,10 mol/l perchloric acid (8.4) through the end point which occurs at about 600 mV.Colorimetric end po
40、int determinations can also be used. Suitable indicators are patent blue VF or crystal violet. Typically, 10 drops of a 0,3 % 0,5 % (m/v) indicator solution is used.9.4 Under normal circumstances, the blank value is negligibly small and is not included in the calculation. However, a solvent blank sh
41、ould preferably be evaluated at suitable intervals to confirm that the solvent blank is indeed a negligible value.NOTE Some laboratories report using this general procedure for lower levels of basicity, employing 0,01 mol/l perchloric acid as the titrant. Better results are reported at low levels wi
42、th a colorimetric end point determination. No blank is needed since the solvent is neutralized to a green end point before the test solution is added. Precision data reported in this International Standard are based on the range 0,3 % to 10 % nitrogen. Precision data at lower ranges of nitrogen are
43、not available at the current time. Therefore, precision studies will be necessary before the method is applied to ranges below 0,3 % nitrogen. ISO 2014 All rights reserved 3BS ISO 25761:2014ISO 25761:2014(E)10 Expression of results10.1 Calculate the basicity of the sample, as percent nitrogen (% N)
44、as follows:%,N=VFm141000100 whereV is the volume of titrant used to reach the end point of the test solution titration, in ml;F is the factor for the concentration of the perchloric acid solution used as the titrant (calcu-lated as described in Annex A);m is the mass of the sample, in g;1,4 is the p
45、roduct of the atomic mass of nitrogen (14) and the nominal concentration of the perchloric acid (0,1 mol/l);1 000 is a conversion factor to convert grams to milligrams.10.2 It is permissible to also report the results as alkalinity in mg of KOH/g of sample, as follows:Alkalinity (total amine value a
46、s mg KOH/g) =VFm5,61where 5,61 is the product of the molecular mass of KOH (56,1) and the nominal concentration of the perchloric acid (0,1 mol/l); the other symbols are as defined in 10.1.11 Precision and bias11.1 GeneralTable 1 is based on a round-robin involving seven laboratories and conducted i
47、n 2002 in accordance with ASTM E 180. All laboratories used potentiometric titration for the generation of the data used in this study. All of the samples were prepared at one source, but the individual test solutions were prepared at the laboratories that tested them. Each test result was the avera
48、ge of two individual determinations. Each laboratory made duplicate determinations on each material on each of two days.Table 1 Round-robin percent nitrogen dataValues in percent nitrogenMaterial Average srsRr R DFA 0,317 0,000 7 0,001 8 0,002 0 0,005 0 5B 2,51 0,004 6 0,005 3 0,012 9 0,014 8 5C 5,8
49、6 0,007 9 0,013 9 0,022 1 0,039 2 5D 9,45 0,022 0 0,021 7 0,061 6 0,061 8 5sris the within-laboratory standard deviation from the mean;sRis the between-laboratory standard deviation from the mean;r is the within-laboratory repeatability limit (= 2,8sr);R is the between-laboratory reproducibility limit (= 2,8sR);DF is the number of degrees of freedom in the data.4 ISO 2014 All rights reservedBS ISO 25761:2014ISO 25761:2014(E)11.2 Precision11.2.1 Repeatability, r: Comparing two replicate results for the
