1、BRITISH STANDARD BS EN ISO 2554:1999 BS2782-4: Method 432C: 1997 Implementing Amendment No.1 to BS2782-4: Method432C:1997 not published separately (renumbers the BS as BS EN ISO 2554:1999) Plastics Unsaturated polyester resins Determination of hydroxyl value The European Standard EN ISO2554:1998 has
2、 the status of a BritishStandard ICS 83.080.10BSENISO 2554:1999 This British Standard, having been prepared under the directionof the Sector Board for Materials and Chemicals, was published under the authority ofthe Standards Board and comesinto effect on 15August1997 BSI 05-1999 ISBN 0 580 28036 5
3、National foreword This part of BS EN ISO 2554 has been prepared by Technical Committee PRI/21 and is the English language version of EN ISO 2554:1998 Plastics Unsaturated polyester resins Determination of hydroxyl value, published by the European Committee for Standardization. The UK participation i
4、n its preparation was entrusted to Technical Committee PRI/21, Testing of plastics, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interes
5、ts informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referre
6、d to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contra
7、ct. 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, pages i and ii, theEN ISO title page, page2, the
8、ISO title page, page ii, pages1 to4 and abackcover. 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. Amendments issued since publication Amd. No. Date Comments 10258 February1999 Imp
9、elementation of the European StandardBSENISO2554:1999 BSI 05-1999 i Contents Page National foreword Inside front cover Foreword 2 Foreword ii Text ofISO2554 1ii blankEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 2554 July 1998 ICS 83.080.10 Descriptors: See ISO document English version Pl
10、astics Unsaturated polyester resins Determination of hydroxyl value (ISO2554:1997) Plastiques Rsines de polyesters non saturs Dtermination de lindice dhydroxyle (ISO2554:1997) Kunststoffe Ungesttigte Polyesterharze Bestimmung der Hydroxylzahl (ISO2554:1997) This European Standard was approved by CEN
11、 on12 June1998. CEN members are bound to comply with the CEN/CENELEC Internal Regulations 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
12、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 version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Centr
13、al Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European C
14、ommittee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref. No. EN ISO2554:1998 EENISO2554:1998 BS
15、I 05-1999 2 Foreword The text of the International Standard from Technical Committee ISO/TC61, Plastics, of the International Organization for Standardization (ISO) has been taken over as an European Standard by Technical Committee CEN/TC249, Plastics, the Secretariat of which is held by IBN. This E
16、uropean Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by January1999, and conflicting national standards shall be withdrawn at the latest by January1999. According to CEN/CENELEC Internal Regulations, the follow
17、ing countries are bound to implement this European Standard: Austria, Belgium, CzechRepublic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and theUnitedKingdom. Endorsement notice The text of the Internation
18、al Standard ISO2554:1997 has been approved by CEN as a European Standard without any modification. NOTENormative references to International Standards are listed in Annex ZA (normative). Contents Page Foreword 2 1 Scope 1 2 Normative references 1 3 Definitions 1 4 Principle 1 5 Reagents 1 6 Apparatu
19、s 1 7 Procedure 2 8 Expression of results 2 9 Precision 2 10 Test report 3 Annex ZA (normative) Normative referencestointernational publications withtheirrelevant European publications 4BSENISO2554:1999 ii BSI05-1999 Foreword ISO (the International Organization for Standardization) is a worldwide fe
20、deration 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 right to be represented on that com
21、mittee. 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. Draft International Standards adopted by the
22、technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least75% of the member bodies casting a vote. International Standard ISO2554 was prepared by Technical Committee ISO/TC61, Plastics, Subcommittee SC12, Thermosetting
23、materials. This second edition cancels and replaces the first edition (ISO2554:1974), of which it constitutes a minor (editorial) revision. Descriptors: Plastics, thermosetting resins, polyester resins, tests, chemical tests, determination, hydroxyl value.BSENISO 2554:1999 BSI 05-1999 1 1 Scope This
24、 International Standard specifies a method for determining the hydroxyl value of unsaturated polyester resins. In fact, this method determines the difference between the hydroxyl value and the acid value; it is therefore necessary to determine the total acid value separately, in order to calculate t
25、he hydroxyl value. NOTE 1The hydroxyl value of saturated polyester resins (for example, polyester resin used for the manufacture of polyurethanes and polymeric plasticizers) and of certain types of alkyd resins may also be determined by this method. 2 Normative references The following standards con
26、tain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investig
27、ate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 2114:1996, Plastics Unsaturated polyester resins Determination of partial acid value and total acid value. ISO 3696:198
28、7, Water for analytical laboratory use Specification and test methods. 3 Definitions For the purposes of this International Standard, the following definitions apply: 3.1 hydroxyl value the number of milligrams of potassium hydroxide necessary to neutralize the acetic acid which will combine, by ace
29、tylation, with1g of an unsaturated polyester resin 3.2 acid value the number of milligrams of potassium hydroxide required to neutralize1g of a test sample under the test conditions 3.3 total acid value the acid value corresponding to the neutralization of all carboxyl-terminated groups and free aci
30、ds and free anhydrides of a polyester 4 Principle The hydroxyl groups in the resin are acetylated by reacting an ethyl acetate solution of the resin with acetic anhydride in the presence of toluene-4-sulfonic acid catalyst. The excess acetic anhydride is hydrolysed by a pyridine/water mixture and th
31、e resultant acetic acid is titrated with methanolic potassium hydroxide solution. In this titration, the free acid and free anhydride groups which exist in the resin are also neutralized by the potassium hydroxide. The hydroxyl value is finally calculated by taking into account the total acid value
32、determined separately by ISO2114. 5 Reagents During the analysis, use only reagents of recognized analytical grade and water of grade3 purity as defined in ISO3696. 5.1 Acetic anhydride acetylating solution, approximately1mol/l, in ethyl acetate. Dissolve1,4g of pure, dry toluene-4-sulfonic acid in1
33、11ml of anhydrous ethyl acetate. When completely dissolved, slowly add, while mixing,12ml of freshly distilled acetic anhydride. Store in a dry atmosphere. 5.2 Ethyl acetate, anhydrous. 5.3 Pyridine/water mixture,3+ 2 (V/V). Mix3 volumes of pyridine with2 volumes of water. WARNING Pyridine is toxic.
34、 Do not inhale the vapour and avoid all contact with the skin and eyes. Work under a fume-extraction hood or in a well ventilated space. 5.4 1-Butanol/toluene mixture,2+1 (V/V). Mix2 volumes of1-butanol with1 volume of toluene. 5.5 Mixed-indicator solution Mix3 volumes of a0,1% ethanolic solution of
35、 thymol blue with1 volume of a0,1% ethanolic solution of cresol red. 5.6 Potassium hydroxide,0,5 mol/l standard volumetric solution in methanol. 6 Apparatus Ordinary laboratory apparatus plus the following: 6.1 Conical flask, capacity250ml, with a ground-glass stopper. 6.2 Magnetic stirrer, with a s
36、tirrer bar covered with a corrosion-resistant material (for example PTFE). 6.3 Burette, capacity50ml, graduated at0,05ml intervals.BSENISO2554:1999 2 BSI 05-1999 6.4 Water bath, controlled at a temperature of50C 1 C. 6.5 Pipettes, capacity5ml and10ml (for the acetylating solution). 6.6 Apparatus for
37、 potentiometric titration: a suitable potentiometer equipped with a calomel reference electrode/glass electrode system, with a titration stand. 6.7 Analytical balance, having an accuracy of1mg. 7 Procedure Weigh, to the nearest1mg, into the250ml conical flask(6.1), a test portion of the resin contai
38、ning approximately5 milli-equivalents of OH (the mass in grams of the test portion=280 divided by the hydroxyl value). If the approximate hydroxyl value is not known, carry out preliminary tests. Add exactly10ml of the acetylating solution(5.1) and the stirrer bar (see6.2). Stopper the conical flask
39、 after moistening the stopper with ethyl acetate(5.2), and dissolve the test portion using the magnetic stirrer(6.2). Should the sample not dissolve completely on warming, add another5ml or10ml of acetylating solution. Place the conical flask in the water bath(6.4) at50C 1 C, taking care to immerse
40、it only about10mm, and leave it for45 min. (This time may be reduced, for example to30 min or less, provided it can be shown that equivalent results are obtained.) Remove the conical flask from the bath, cool, place on the magnetic stirrer and add2ml of water. When the solution has been thoroughly m
41、ixed, add10ml of pyridine/water mixture(5.3) and stir for5min. Rinse the stopper and inner surface of the conical flask with60ml of1-butanol/toluene mixture(5.4) and add5 drops of mixed-indicator solution(5.5). Continue stirring and titrate with methanolic potassium hydroxide solution(5.6). When the
42、 colour change is observed, add a further1 or2 drops of the mixed indicator. The solution changes from yellow to clear; note the volume V 1 , in millilitres, of potassium hydroxide solution used. Add a further drop of potassium hydroxide solution; the indicator should turn blue. If it does not, note
43、 the burette reading and add a further drop of the mixed-indicator solution, continuing in this way until the blue colour is obtained. The value of V 1to be used for the calculation is the one noted before adding the drop which produced the blue colour. Carry out a blank test under the same conditio
44、ns, but without the test portion, and note the volume V 0 , in millilitres, of potassium hydroxide solution used. Carry out at least two determinations. The results of the two determinations should not differ by more than2 hydroxyl-value units. If this is not the case, carry out further determinatio
45、ns until the results of two consecutive determinations meet this requirement. An alternative method consists in carrying out the determination by potentiometric titration instead of using a colour indicator. This method, which is usable in all cases, is recommended especially with densely coloured p
46、roducts. Use a calomel reference electrode, with a bridge containing a saturated solution of potassium chloride in methanol, and a glass electrode connected to a pH-meter or to a millivoltmeter. 8 Expression of results For each of the two determinations, calculate the hydroxyl value HV from the equa
47、tion where NOTE 2The value of (V 0 V 1 ) may be positive or negative. Calculate the average of the two values obtained and round to the nearest whole number. 9 Precision The precision of this method is not known because interlaboratory data are not available. Interlaboratory data are being obtained,
48、 and a precision statement will be added at the next revision. V 1 is the volume, in millilitres, of standard volumetric potassium hydroxide solution(5.6) used in the determination; V 0 is the volume, in millilitres, of standard volumetric potassium hydroxide solution(5.6) used in the blank test; c
49、is the exact concentration, in moles per litre, of the standard volumetric potassium hydroxide solution used; m is the mass, in grams, of the test portion; AV is the total acid value, determined in accordance with ISO2114.BSENISO 2554:1999 BSI 05-1999 3 10 Test report The test report shall include the following particulars: a) a reference to this International Standard; b) all details necessary for the complete identification of the sample; c) the individual results and their mean; d) details of any operation not specified in
