【英国标准word原稿】BS EN 1240-1998 Adhesives. Determination of hydroxyl value and-or hydroxyl content.doc

豆丁网：/kmust1british standardadhesives determination of hydroxyl value and/orhydroxyl contentthe european standard en 1240:1998 has the status of abritish standardics 83.180| bs en1240:1998|第 5 页 共 13 页豆丁网：/kmust1licensed copy: sheffieldun sheffieldun, na, sat oct 28 09:00:43 gmt+00:00 2006, uncontrolled copy, (c) bsi|no copying without bsi permission except as permitted by copyright lawbs en 1240:1998national forewordthis british standard is the english language version of en 1240:1998.the uk participation in its preparation was entrusted to technical committeesti/52, adhesives, which has the responsibility to: aid enquirers to understand the text; present to the responsible european committee any enquiries on the interpretation, or proposals for change, and keep the uk interests 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-referencesthe british standards which implement international or european publications referred to in this document may be found in the bsi standards catalogue under the section entitled international standards correspondence index, or by using thefind facility of the bsi standards electronic catalogue.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 legal obligations.summary of pagesthis document comprises a front cover, an inside front cover, the en title page, pages 2 to 4, an inside back cover and a back cover.licensed copy: sheffieldun sheffieldun, na, sat oct 28 09:00:43 gmt+00:00 2006, uncontrolled copy, (c) bsiamd. no.datetext affectedthis british standard, having been prepared under the direction of the sector board for materials and chemicals, was published under the authority of the standards board and comes into effect on 15 july 1998bsi 1998isbn 0 580 29640 7amendments issued since publicationeuropean standarden 1240norme europe enneeuropa ische normfebruary 1998ics 83.180descriptors: adhesives, components, chemical tests, determination, hydroxyl value, procedureenglish versionadhesives determination of hydroxyl value and/or hydroxyl contentadhe sifs de termination de la valeur hydroxyle et/ou de la teneur en hydroxyleklebstoffe bestimmung der hydroxylzahl und/oder des hydroxylgehalteslicensed copy: sheffieldun sheffieldun, na, sat oct 28 09:00:43 gmt+00:00 2006, uncontrolled copy, (c) bsithis european standard was approved by cen on 2 january 1998.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 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 central secretariat has the same status as the official versions.cen members are the national standards bodies of austria, belgium, czech republic, denmark, finland, france, germany, greece, iceland, ireland, italy, luxembourg, netherlands, norway, portugal, spain, sweden, switzerland and united kingdom.ceneuropean committee for standardization comite europe en de normalisation europa isches komitee fu r normungcentral secretariat: rue de stassart 36, b-1050 brussels1998 cen all rights of exploitation in any form and by any means reserved worldwide for cen nationalmembers.ref. no. en 1240:1998 epage en 1240:1998bsi 1998forewordthis european standard has been prepared bytechnical committee cen/tc 193, adhesives, thecontentspagelicensed copy: sheffieldun sheffieldun, na, sat oct 28 09:00:43 gmt+00:00 2006, uncontrolled copy, (c) bsisecretariat of which is held by aenor.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 august 1998, and conflicting national standards shall be withdrawn at the latest by august 1998.according to the cen/cenelec internal regulations, the national standards organizations of the following countries are bound to implement this european standard: austria, belgium, czech republic, denmark, finland, france, germany, greece, iceland, ireland, italy, luxembourg, netherlands, norway, portugal, spain, sweden, switzerland and the united kingdom.foreword 21scope 32normative references 33definitions 34principle 35safety 36reagents 37apparatus 38procedure 49expression of results 410test report 4page 3en 1240:19981 scopethis standard specifies a method to determine the hydroxyl value and/or the hydroxyl content of adhesives, adhesive components, their basic constituents and related products. this method can also be used to determine the hydroxyl value and/or the hydroxyl content of surface protection systems of concrete.2 normative referencesthis european standard incorporates by dated or undated reference, provisions from other publications. these normative references are cited at the appropriate places in the text and the publications are listed hereafter. for dated references, subsequent amendments to or revisions of any of these publications apply to this european standard onlywhen incorporated in it by amendment or revision. for undated references the latest edition of the publication referred to applies.en 923, adhesives terms and definitions. en 1066, adhesives sampling.en 1067, adhesives examination and preparation of samples for testing.en 1241, adhesives determination of acid value. en iso 3696, water for analytical laboratory use specification and test methods. (iso 3696:1987)en 21512, paints and varnishes sampling of products in liquid or paste form. (iso 1512:1991) iso 385-1, laboratory glassware burettes part 1: general requirements.iso 648, laboratory glassware one-mark pipettes. iso 1042, laboratory glassware one-mark volumetric flasks.3 definitionsfor the purposes of this standard, the definitions in accordance with en 923 and the following definitions apply:3.1hydroxyl valuethe number of milligrams of potassium hydroxide necessary to neutralize the acetic acid which will combine by acetylation with 1 g of the product under test3.2hydroxyl contentmass fraction in percentage of hydroxyl groups (oh)contained in the product under test4 principleacetylation of the hydroxyl groups is carried out by acetic anhydride on a pyridine solution of the product under test.the excess acetic anhydride is hydrolysed by the addition of water and the resultant acetic acid titrated with aqueous potassium hydroxide solution.5 safetypersons using this standard shall be familiar with normal laboratory practice.this standard does not purport to address all safety problems, if any, associated with its use.it is the responsibility of the user to establish safety and health practices and to ensure compliance with any european and national regulatory conditions.6 reagents6.1 acetic anhydride, analytical grade.6.2 pyridine, analytical grade.6.3 acetylation solution: add slowly, while mixing,28 ml of acetic anhydride (see 6.1) to 200 ml of pyridine (see 6.2) and store in a dry atmosphere.6.4 water for analytical laboratory use, grade 3 as specified in en iso 3696.6.5 phenolphthalein (mass concentration b = 0,1 %) indicator solution: dissolve 0,1 g of phenolphthalein, dilute in 100 ml of pyridine (see 6.2) to 100 ml, and make this solution faintly pink by addition of potassium hydroxide solution.6.6 potassium hydroxide, carbonate-free, 1m aqueous solution.7 apparatusall volumetric glassware shall be class a, in accordance with iso 385-1, iso 648 or iso 1042 as appropriate.7.1 analytical balance, with a scale division of0,1 mg.7.2 conical flask, capacity 250 ml, with a ground glass stopper.7.3 one-mark pipette, capacity 20 ml.7.4 water-cooled reflux condenser, length 50 cm, inside diameter approximately 9 mm, with ground glass joints to fit the flasks (see 7.2). it shall be fitted on its top with a guard tube containing anhydrous calcium chloride.7.5 water bath, controlled at 100 8c.7.6 burette, capacity 50 ml, graduated in 0,05 ml.7.7 apparatus for potentiometric titration, optional or if necessary, e.g. for dark coloured solutions.licensed copy: sheffieldun sheffieldun, na, sat oct 28 09:00:43 gmt+00:00 2006, uncontrolled copy, (c) bsibsi 1998page en 1240:1998bsi 19988 proceduretake a sample of the product to be tested in accordance with en 1066. for surface protection systems take a sample in accordance with pren 21512. examine and prepare this sample for testing in accordance with en 1067 or pren 21512 as9 expression of results9.1 calculation of the hydroxyl value ohv from the three test results obtained, calculate the hydroxyl value ohv by the equation:v2 2 v1appropriate.weigh, to the nearest 1 mg, in a 250 ml conical flask(see 7.2) a test portion the mass of which is calculatedohv = 56,1 3 m 3 mwhere:+ avfrom the expected hydroxyl value or hydroxyl content by the following formulae:test portion in grams =m is the molarity of the potassium hydroxide solution;v1 is the volume, in millilitres, of the potassium280hydroxyl value8,5or hydroxyl contenthydroxide solution (see 6.6) required for the determination;note 1 if the approximate hydroxyl content or the approximatehydroxyl value is not known, preliminary tests should be made.add to the sample 20 ml of the acetylation solution (see 6.3) with a one-mark pipette (see 7.3) and some dry anti-bumping granules.note 2 the anti-bumping granules are neutral. in case of doubt, granules should be boiled with water and dried carefully.fit the reflux condenser (see 7.4) to the conical flask and ensure the tightness of the joint by moistening with some drops of pyridine (see 6.2).place the flask containing the sample in a water bath controlled at 100 8c and reflux for 60 min.remove the flask from the bath, cool with coldrunning water to approximately 20 8c and add through the condenser 40 ml of water (see 6.4). mix thoroughly and cool again.v2 is the volume, in millilitres, of the potassium hydroxide solution (see 6.6) required for the blank test;av is the acid value determined in accordance withen 1241;m is the mass, in grams, of the test portion.note the value of (v2 2 v1) can be positive or negative.9.2 calculation of the percentage of hydroxyl content (oh %)calculate the hydroxyl content oh % from the hydroxyl value ohv (see 9.1) by following the equation:1,7 3 ohvnote 3 the reaction time can be reduced by adding a suitable catalyst, for example by the addition of an acid liketoluene-4-sulfonic acid to unsaturated polyester resins or basic catalysts like tertiary amines to other polyol compounds.(oh %) =56,1= 0,03 3 ohvlicensed copy: sheffieldun sheffieldun, na, sat oct 28 09:00:43 gmt+00:00 2006, uncontrolled copy, (c) bsicomparative tests should be carried out to demonstrate that equivalent values are obtained by the use of the specific catalyst when a reduced reaction time is applied.rinse any product adhering to the inner surface of the condenser with water (see 6.4) into the flask. dissolve any precipitate by the addition of 30 ml of pyridine(see 6.2).add five drops of phenolphthalein solution (see 6.5) and titrate with the aqueous potassium hydroxide solution (see 6.6) until the colour changes to pink or use a potentiometric apparatus (see 7.7) for the end point detection. record the volume v1, in millilitres, of the potassium hydroxide solution used.carry out a blank test under the same conditions with the acetylation solution (see 6.3) but without the test portion, and note the volume v2, in millilitres, of potassium hydroxide solution used.at least three tests shall be carried out. the mean value shall not differ by more than 0,1 % of the hydroxyl content or two units of the hydroxyl value. if this is not the case, further tests shall be carried out until the values of three consecutive tests fulfil the requirement.note 4 the free acid groups which exist in the product are also neutralized by the potassium hydroxide. therefore, in the final calculation of hydroxyl value and/or hydroxyl content an acid value of the product under test should be taken into account, determined in accordance with en 1241 separately.10 test reportthe test report shall include:a) a reference to this european standard;b) a complete identification of the sample;c) identification of the end point detection used(indicator or potentiometry);d) test results, individual values and their mean;e) any operations not specified in this european standard, or the document to which reference is made, and all incidents that may have affected the results;f) the date of test.blanklicensed copy: sheffieldun 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