1、BRITISH STANDARD BS EN ISO 7327:1997 Incorporating amendment No. 1 to BS 2782-4:Method 433E:1996 (renumbers the BS as BS EN ISO 7327:1997) Plastics Hardenersand accelerators for epoxide resins Determination of free acid in acid anhydride The European Standard ENISO7327:1997 has the status of a Briti
2、sh Standard ICS 83.080.10BSENISO7327:1997 This British Standard, having been prepared under the directionof the Sector Board forMaterials and Chemicals, waspublished under the authorityof the Standards Boardand comes into effect on 15 January 1996 BSI 04-2000 The following BSI references relate to t
3、he work on this standard: Committee reference PRI/21 Draft for comment 88/42916 DC ISBN 0 580 24948 4 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee PRI/21, Testing of plastics, upon which the following bodies were repre
4、sented: British Apparel and Textile Confederation British Plastics Federation Department of the Environment (Building Research Establishment) Department of Trade and Industry (National Physical Laboratory) Electrical and Electronic Insulation Association (BEAMA Ltd.) GAMBICA (BEAMA Ltd.) Institute o
5、f Materials Ministry of Defence Packaging and Industrial Films Association PIRA International RAPRA Technology Ltd. Royal Society of Chemistry Amendments issued since publication Amd. No. Date Comments 9699 November 1997 Indicated by a sideline in the marginBSENISO7327:1997 BSI 04-2000 i Contents Pa
6、ge Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN ISO 7327 3 List of references Inside back coverBSENISO7327:1997 ii BSI 04-2000 National foreword This British Standard has been prepared by Technical CommitteePRI/21 and is the English language version of ENISO73
7、27:1997 Plastics Hardeners and accelerators for epoxide resins Determination of free acid in acid anhydride. It is identical with ISO7327:1994 published by the International Organization for Standardization (ISO). A British Standard does not purport to include all the necessary provisions of a contr
8、act. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theEN ISOtitle page, pages2 to4, a
9、n inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM ENISO 7327 June 1997 ICS83.080.10 Descriptors:
10、 Plastics, epoxy resins, resin hardeners, anhydrides, chemical analysis, determination of content, acids English version Plastics Hardeners and accelerators for epoxide resins Determination of free acid in acid anhydride (ISO 7327:1994) Plastiques Durcisseurs et acclrateurs pour rsines poxydes Dterm
11、ination de lacide libre dans lacide-anhydride (ISO 7327:1994) Kunststoffe Hrter und Beschleuniger fr Epoxidharze Bestimmung der freien Sure in Surenanhydrid (ISO 7327:1994) This European Standard was approved by CEN on1997-05-28. CEN members are bound to comply with the CEN/CENELEC Internal Regulati
12、ons which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This Europ
13、ean Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the natio
14、nal standards bodies of Austria, Belgium, CzechRepublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and UnitedKingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches
15、Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1997 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national members. Ref. No. EN ISO 7327:1997 EENISO7327:1997 BSI 04-2000 2 Foreword The text of the International Standard from Techn
16、ical Committee ISO/TC61, Plastics of the International Organization for Standardization (ISO) has been taken over as a European Standard by Technical Committee CEN/TC249, Plastics, the secretariat of which is held by IBN. This European Standard shall be given the status of a national standard, eithe
17、r by publication of an identical text or by endorsement, at the latest by December1997, and conflicting national standards shall be withdrawn at the latest by December1997. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to
18、 implement this European Standard: Austria, Belgium, CzechRepublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the UnitedKingdom. Contents Page Foreword 2 1 Scope 3 2 Normative reference 3 3 Principle
19、3 4 Reagents 3 5 Apparatus 3 6 Procedure 4 7 Expression of results 4 8 Test report 4ENISO7327:1997 BSI 04-2000 3 1 Scope This International Standard specifies a method for the determination of free acid in acid anhydride hardeners and accelerators for epoxide resins. NOTE 1This method is suitable fo
20、r most anhydrides except for polyester and oligomeric anhydrides which may give too wide a scatter of results. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the
21、 edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currentl
22、y valid International Standards. ISO 760:1978, Determination of water Karl Fischer method (General method). 3 Principle The small amount of free acid present in a test portion of acid anhydride hardener or accelerator is reacted with rhodamine6G to colour the test solution pink. The absorbance of th
23、e coloured solution is measured at a wavelength of about510nm using a spectrometer, and the free-acid content determined from a calibration curve. 4 Reagents During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water or water of equivalent
24、 purity. 4.1 Butan-2-one (methyl ethyl ketone), dried using the following procedure: Put 100g of molecular sieve4A into1litre of butan-2-one. After allowing to settle for24h, decant off the supernatant liquid, taking care that it does not contain any molecular sieve4A particles. Determine the water
25、content of the dried butan-2-one by the Karl Fischer method (seeISO760). Reject butan-2-one containing more than20ppm of water. 4.2 Toluene, dried using the following procedure: Put 100g of molecular sieve4A into1litre of toluene. After allowing to settle for24h, decant off the supernatant liquid, t
26、aking care that it does not contain any molecular sieve4A particles. Determine the water content of the dried toluene using the Karl Fischer method (seeISO760). Reject toluene containing more than20ppm of water. 4.3 Rhodamine 6G solution 4.3.1 Preparation Disperse 20mg of rhodamine 6G in10ml of a bu
27、ffer solution 0,1g of sodium phosphate (Na 3 PO 4 ) dissolved in10ml of water. Pour the dispersion into a500ml separating funnel and add200ml of toluene (4.2). Shake gently until the layer of toluene becomes yellowish brown. After allowing to settle for1h, filter the organic phase through filter pap
28、er into a brown-coloured bottle. Add metallic sodium slices (grains sliced with a scalpel) to the filtrate, and allow the filtrate to stand for12h. Prior to use, check the solution to ensure that the water content is less than20ppm and the blank value of the absorbance is in the range0,30 to0,50. 4.
29、3.2 Determination of absorbance of blank solution Determine the absorbance of a blank rhodamine6G solution (4.3.1) by the following procedure. Introduce, using a pipette (see5.5),2ml of the rhodamine6G solution into a10ml volumetric flask, and make up to the mark with a solvent mixture of95parts by
30、volume of dried toluene (4.2) and five parts by volume of dried butan-2-one (4.1). Determine the absorbance of this solution as specified in6.3.2. 4.4 Standard sample of free acid Boil 10g of the acid anhydride with 60ml of water for3h and allow to cool. Filter, wash the precipitate with water, and
31、then dry it. 5 Apparatus Ordinary laboratory apparatus, plus the following: 5.1 Balance, accurate to 0,1 mg. 5.2 Spectrometer, with absorption cells with an optical path length of10mm. 5.3 Conical flask, capacity50ml, fitted with a ground-glass stopper. 5.4 One-mark volumetric flasks, capacity10ml,5
32、0ml and100ml, respectively, each fitted with a ground-glass stopper. 5.5 Pipettes, capacities1ml,1,5ml,2ml,2,5ml and10ml.ENISO7327:1997 4 BSI 04-2000 6 Procedure 6.1 Preparation of test solution Weigh out, to an accuracy of0,1mg,0,2g of the sample, place it in a50ml conical flask (5.3), add30ml of a
33、 solvent mixture of95parts by volume of dried toluene (4.2) and five parts by volume of dried butan-2-one (4.1), and dissolve at room temperature. Transfer the solution to a50ml volumetric flask (5.4) and make up to the mark with dried solvent mixture. (The concentration of the test solution thus pr
34、epared is between10 4 mol and10 5mol of free acid per litre.) 6.2 Calibration of spectrometer Place 20mg of the standard sample of free acid (4.4) in a100ml volumetric flask (5.4) and add50ml of dried butan-2-one (4.1). Dissolve the free acid completely at room temperature. Then make up to the mark
35、with dried toluene (4.2). Using a pipette (see5.5), transfer10ml of this solution to another100ml volumetric flask (5.4) and make up to the mark with dried toluene (4.2). (The concentration of the standard solution thus obtained is20mg of free acid per litre.) Using pipettes (see5.5), measure out1ml
36、,1,5ml,2ml and2,5ml portions of the free-acid standard solution prepared above, react each with rhodamine6G as specified in6.3.1 and measure the absorbance of each calibration solution thus obtained as specified in6.3.2. Subtract the blank absorbance value determined in4.3.2 from the absorbance obta
37、ined for each calibration solution and plot a graph of corrected absorbance (vertical axis) versus the mass, in micrograms, of free acid in10ml of the corresponding calibration solution (horizontal axis). Then draw the calibration curve, passing through the origin. 6.3 Determination 6.3.1 Formation
38、of the absorbing compound Using a pipette (see5.5), introduce2ml of rhodamine6G solution (4.3) into a10ml volumetric flask (5.4) and add between1ml and5ml of the test solution (see6.1). Rhodamine6G and free acid will react immediately to yield a pink colour. Make the resultant solution up to the mar
39、k with the solvent mixture of dried toluene and dried butan-2-one as used in6.1. The volume of test solution taken shall be chosen to give a pink colour. The intensity of colour shall not be greater than that of the deepest-colour calibration solution. 6.3.2 Spectrometric measurements Measure the ab
40、sorbance of the solution prepared in6.3.1 at a wavelength of510nm 10nm using the spectrometer (5.2) and cells with an optical path length of10mm, having first zeroed the spectrometer with dried toluene (4.2) in the absorption cell. Since the absorbance of the test solution changes with time, measure
41、 it within5min of the formation of the absorbing compound. Subtract the absorbance of the blank solution determined in4.3.2 and read from the calibration curve plotted in6.2 the mass of free acid in10ml of the solution prepared in6.3.1. 7 Expression of results The free-acid content of the acid anhyd
42、ride, expressed as a percentage by mass, is given by the formula where 8 Test report The test report shall include the following particulars: a) a reference to this International Standard; b) all details necessary for identification of the sample submitted for testing; c) the water content of the so
43、lvents used; d) the results of the test and the units in which they have been expressed. m 0 is the mass, in milligrams, of the test portion (see6.1); m 1 is the mass, in micrograms, of free acid in10ml of the test solution, as read off the calibration curve (see6.2); r D is the dilution factor, i.e
44、.50 divided by the volume, in millilitres, of the test solution used in6.3.1. m 1 r D 10 1 m 0 -BSENISO7327:1997 BSI 04-2000 List of references See national foreword.BS EN ISO 7327:1997 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body respo
45、nsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions BritishStandards are updated by amendment or revision. Users of BritishStandards should make sure that they possess the latest amendmen
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