1、BRITISH STANDARD BS EN ISO 8975:1995 BS2782-4: Method451K Plastics Phenolic resins Determination of pH The European Standard EN ISO8975:1995 has the status of a British Standard ICS 83.080.10BSENISO8975:1995 This British Standard, having been prepared under the directionof the Sector Board forMateri
2、als and Chemicals, waspublished under the authorityof the Standards Boardand comes into effect on 15November1995 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference PRI/21 Draft announced in BSI News August1994 ISBN 0 580 24908 5 Committees responsible f
3、or 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 represented: The British Apparel and Textile Confederation British Plastics Federation Department of the Environment (Building Rese
4、arch Establishment) Department of Trade and Industry (National Physical Laboratory) Electrical and Electronic Insulation Association (BEAMA Ltd.) GAMBICA (BEAMA Ltd.) Institute of Materials Ministry of Defence Packaging and Industrial Films Association PIRA International RAPRA Technology Ltd. Royal
5、Society of Chemistry Amendments issued since publication Amd. No. Date CommentsBSENISO8975:1995 BSI 12-1999 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 1 Scope 3 2 Principle 3 3 Reagents 3 4 Apparatus 3 5 Procedure 3 6 Expression of results 4 7 Test repo
6、rt 4 Annex A (informative) Plastics Solid phenolic resins Determination of pH Inside back coverBSENISO8975:1995 ii BSI 12-1999 National foreword This British Standard has been prepared by Technical Committee PRI/21 and is the English language version of EN ISO8975:1995 Plastics Phenolic resins Deter
7、mination of pH published by the European Committee for Standardization (CEN). It was derived by CEN from ISO8975:1989 published by the International Organization for Standardization (ISO). This standard has been dual numbered and is contained in the BS2782 series of tests as BS2782-4:Method451K. It
8、supersedes BS2782-4:Method451K:1978 which is withdrawn. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from lega
9、l obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theEN ISO title page, pages2 to4, an 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
10、 the amendment table on the inside front cover.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO8975 July1995 ICS 83.080.10 Descriptors: Plastics, phenoplasts, resins,determination, pH English version Plastics Phenolic resins Determination of pH (ISO8975:1989) Plastiques Rsines phnoliques Dte
11、rmination du pH (ISO8975:1989) Kunststoffe Phenolharze Messung des pH-Wertes (ISO8975:1989) This European Standard was approved by CEN on 1994-12-14. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status
12、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 European Standard exists in three official versions (English, French, German). A vers
13、ion 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 national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Gre
14、ece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1995 All rights of
15、 reproduction and communication in any form and by any means reserved in all countries to CEN and its members Ref. No. EN ISO8975:1995 EENISO8975:1995 BSI 12-1999 2 Foreword The text of the International Standard from ISO/TC61, Plastics, of the International Organization for Standardization (ISO) ha
16、s been taken over as a European Standard by the Technical Committee CEN/TC249, Plastics. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by January1996, and conflicting national standards shall be wi
17、thdrawn at the latest by January1996. According to CEN/CENELEC Internal Regulations, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden,
18、Switzerland and theUnited Kingdom.ENISO8975:1995 BSI 12-1999 3 1 Scope This International Standard specifies a method for the determination of the pH of liquid phenolic resins at the manufacturing stage or on the market. NOTE 1A variant of this method, applicable to solid phenolic resins, is describ
19、ed in Annex A. With liquid resins having a viscosity greater than2Pas, it may be necessary to use this variant, which calls for a magnetic stirrer. 2 Principle The potential difference between a glass electrode and a reference electrode immersed in the same solution is used to determine the pH. 3 Re
20、agents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. Standard solutions, with acid pH( 4), neutral pH( 7) or alkaline pH( 9), or buffer solutions. The following standard or buffer solutions are specified: 3.1 Potassium h
21、ydrogen phthalate, standard solution, c(KCOOC 6 H 4 COOH)=0,05mol/l, pH=4,00 at23 C. Dissolve10,21g of potassium hydrogen phthalate, previously dried by heating at100 C to130 C for2h, in water and make up to1000ml. This solution shall be stored in a glass vessel and kept away from any traces of acid
22、 or base; it may be kept longer by adding a crystal of thymol. Slight cloudiness in the solution indicates microbial contamination. The thymol is no longer effective and such a solution shall be discarded. 3.2 Hydrogen phosphate buffer solution, containing approximately0,025mol of potassium dihydrog
23、en phosphate (KH 2 PO 4 ) per litre and approximately0,025mol of sodium hydrogen phosphate (Na 2 HPO 4 ) per litre, pH=6,88 at23 C. Dissolve3,39g of potassium dihydrogen phosphate (KH 2 PO 4 ) and3,53g of sodium hydrogen phosphate (Na 2 HPO 4 ), previously dried by heating at110 C to130 C for2h, in
24、water and make up to1000ml. This solution may be kept longer by adding a crystal of thymol. 3.3 Sodium tetraborate (Borax), standard solution, c(Na 2 B 4 O 7 .10H 2 O)=0,01mol/l, pH=9,22 at23 C. Dissolve3,80g of sodium tetraborate decahydrate (Na 2 B 4 O 7 .10H 2 O) in water and dilute to1000 ml. 4
25、Apparatus 4.1 pH-meter, accurate to0,1pH-units. 4.2 Electrodes 4.2.1 Measuring electrode: glass electrode. 4.2.2 Reference electrode: calomel electrode. 4.2.3 Maintenance of the electrodes For all types of electrode, follow the manufacturers instructions specifying the maintenance procedures necessa
26、ry to keep the electrodes in the correct condition. In particular, clean the glass electrode at regular intervals as directed by the manufacturer. NOTE 2When not in use over a long period, glass electrodes and certain calomel electrodes may be stored in the dry condition if permitted by the manufact
27、urer. For reconditioning, soak the glass electrode in acidified distilled water (pH4 to5) for several hours and the calomel electrode in saturated potassium chloride solution. Before each determination, wash the electrodes with water and leave them to soak in water for at least2min before making any
28、 measurements. 5 Procedure 5.1 Test temperature Carry out the test at23 C 0,5 C. 5.2 Calibration of the pH-meter/electrode unit Carry out the calibration in accordance with the manufacturers instructions. For the calibration, use two of the standard or buffer solutions (clause3) which bracket the as
29、sumed value to be measured. 5.2.1 Adjustment of the apparatus Rinse the electrodes with water and lightly wipe the electrode tips (with filter paper, for example) to remove any excess water. Rinse the electrodes with one of the standard or buffer solutions by pouring the liquid down the outside of t
30、he stem. Pour an adequate volume of the same standard or buffer solution into the clean, dry measuring vessel and immerse the electrodes in the solution. Set the pH-meter reading to the pH-value of the standard or buffer solution, taking into account its temperature. Remove the electrodes and discar
31、d the standard or buffer solution contained in the measuring vessel. 5.2.2 Verification of the response accuracy Rinse the electrodes with water and then with the second standard or buffer solution, as described in5.2.1.ENISO8975:1995 4 BSI 12-1999 Wash the measuring vessel with water (or use anothe
32、r clean, dry vessel), rinse it with the second standard or buffer solution, pour an adequate volume of the solution into the vessel and immerse the electrodes in the solution. Record the pH-meter reading without changing the setting of the apparatus and, in particular, without touching the temperatu
33、re correction or calibration/buffer control. If this reading is within the permissible tolerances( 0,1pH-units) at the known pH-value of the standard or buffer solution, taking into account its temperature, the apparatus is in operating condition and is suitably calibrated. If this is not the case,
34、determine the cause (such as operating error, defective electrode, incorrect temperature correction) and remedy the defect. 5.3 Determination 5.3.1 Test portion and preparation of the test solution Allow the temperature of the resin to stabilize at23 C 0,5 C. Prepare a50% (m/m) solution of the resin
35、 in water. If phase separation occurs, wait until a sufficient volume of the aqueous phase for measurement has separated out in a dropping funnel. Transfer the aqueous phase to a graduated flask and carry out the measurement. 5.3.2 Measurement of the pH Once the apparatus has been calibrated, wash t
36、he electrodes(4.2) and the measuring vessel, first with water, then with the test solution, as described in5.2.1 and5.2.2. Mix the test solution, pour an adequate volume of it into the measuring vessel (another dry, clean vessel may also be used) and immerse the electrodes in the solution. Check tha
37、t the pH-meter reading is stable, and, if so, record it. Repeat these operations with a fresh portion of the test solution. If the new reading of the pH-meter is identical to the previous one, or only differs from it by0,2pH-units, the test is complete (unless otherwise indicated in special standard
38、s). If this is not the case, carry out these operations a third time with a fresh portion of the test solution, carrying out all the checks necessary to determine the source of the error. If this third measurement does not give a conclusive result, repeat all the operations, including the calibratio
39、n. In order to determine the pH of a solution likely to change with time, particularly when in contact with the carbon dioxide in the air, proceed under the appropriate conditions (purge with a stream of nitrogen, for example). 6 Expression of results Calculate the mean of the two measurements carri
40、ed out in accordance with5.3.2 and round to the nearest0,1pH-units. 7 Test report The test report shall include the following information: a) a reference to this International Standard; b) a complete identification of the resin tested; c) the test result, calculated as specified in clause6, as well
41、as the test temperature if the latter is not23 C 0,5 C; d) the date of the test.BSENISO8975:1995 BSI 12-1999 Annex A (informative) Plastics Solid phenolic resins Determination of pH A.1 Scope This annex describes a method for determining the pH of solid phenolic resins at the manufacturing stage or
42、on the market. A.2 Principle Preparation of an organo-aqueous solution, using a mixture of solvents previously neutralized to pH7, and measurement of the pH of this solution with a pH-meter. A.3 Reagents The reagents specified in clause3, and A.3.1 Hydrochloric acid, solution, c(HCl) 0,01mol/l. A.3.
43、2 Sodium hydroxide, solution, c(NaOH) 0,01 mol/l. A.3.3 Solvent mixture, with the following composition: NOTE 3If the solid phenolic resin is insoluble in the above solvent mixture, water and toluene or water and xylene mixtures may be used. A.4 Apparatus The apparatus specified in clause4, and A.4.
44、1 Magnetic mixer, with bar magnet. A.4.2 Balance, accurate to1g. A.5 Procedure A.5.1 Calibration of the pH-meter/electrode unit Calibrate using two standard or buffer solutions (clause3) with an acid and neutral pH, respectively. A.5.2 Neutralization of the solvent mixture Place80g 1g, weighed using
45、 the balance(A.4.2), of the solvent mixture(A.3.3) in a250ml beaker. Mix using the magnetic mixer(A.4.1) and allow the temperature of the mixture to stabilize at23 C 0,5 C. Immerse the electrodes of the pH-meter in the beaker and, if necessary, adjust the pH of the mixture to7,0 0,1using either the
46、sodium hydroxide solution(A.3.2) or the hydrochloric acid solution(A.3.1). A.5.3 Determination A.5.3.1 Test portion and preparation of the test solution Introduce20g1g, weighed using the balance(A.4.2), of the finely ground solid resin into the250ml beaker containing80g of the solvent mixture neutra
47、lized as described inA.5.2. Mix using the magnetic mixer(A.4.1) until the resin is completely dissolved and allow the temperature of the solution to stabilize at23 C 0,5 C. A.5.3.2 Measurement of the pH Carry out the measurement as described in5.3.2 on the solution prepared as specified inA.5.3.1. A
48、.6 Expression of results See clause6. A.7 Test report See clause7. Water: 20g 1g Methanol: 40g 1g Acetone: 40g 1gBS EN ISO 8975:1995 BS2782-4: Method451K BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStan
49、dards. 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 amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this BritishStandard would inform the Secretary of
