1、BRITISH STANDARD BS7164-11.2: 1993 Chemical tests for raw and vulcanized rubber Part 11: Butadiene rubber Section 11.2 Method for determination of unsaturationBS7164-11.2:1993 This British Standard, having been prepared under the directionof the Plastics and Rubber Standards Policy Committee, was pu
2、blished underthe authority oftheStandards Board and comes into effect on 15 May1993 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference PRM/23 Draft for comment91/43982DC ISBN 0 580 20979 2 Committees responsible for this British Standard The preparation
3、 of this British Standard was entrusted by the Plastics and Rubber Standards Policy Committee (PRM/-) to Technical Committee PRM/23, upon which the following bodies were represented: Institute of Water and Environmental Management Laboratory of the Government Chemist Ministry of Defence Royal Societ
4、y of Chemistry Rubber and Plastics Research Association Amendments issued since publication Amd. No. Date CommentsBS7164-11.2:1993 BSI 11-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Sampling 1 7 Prepar
5、ation of test sample 1 8 Procedure 1 9 Calculation and expression of units 2 10 Repeatability 2 11 Test report 2 List of references Inside back coverBS7164-11.2:1993 ii BSI 11-1999 Foreword This Section of BS7164 has been prepared under the direction of the Plastics and Rubber Standards Policy Commi
6、ttee and supersedes 9.7 of BS1673-9:1973, which will be deleted by amendment. BS7164 rationalizes all the methods that deal with chemical analysis of raw, compounded and vulcanized rubber, some of which have previously been published in BS903, BS1673 and BS5923. Relevant Parts of those standards wil
7、l be withdrawn or deleted by amendment, as appropriate, when superseded by Parts and Sections of BS7164. This British Standard calls for the use of substances that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user
8、from legal obligations relating to health and safety at any stage. 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 immunit
9、y from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and2, 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 the amend
10、ment table on the inside front cover.BS7164-11.2:1993 BSI 11-1999 1 1 Scope This Section of BS7164 describes a method for the determination of unsaturation in raw polybutadiene rubber (BR) and butadiene based rubbers soluble in carbon tetrachloride. 2 References 2.1 Normative references This Section
11、 of BS7164 incorporates, by reference, provisions from specific editions of other publications. These normative references are cited at the appropriate points in the text and the publications are listed on the inside back cover. Subsequent amendments to, or revisions of, any of these publications ap
12、ply to this Section of BS7164 only when incorporated in it by updating or revision. 2.2 Informative references This Section of BS7164 refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the insi
13、de back cover, but reference should be made to the latest editions. 3 Principle Addition of iodine monochloride to the double bonds present in polybutadiene is carried out in carbon tetrachloride. The excess iodine monochloride liberates iodine from potassium iodide; the iodine is titrated with sodi
14、um thiosulfate. 4 Reagents WARNING. All recognized health and safety precautions should be taken when performing this method of analysis. 4.1 General. Use only reagents of recognized analytical grade and any grade of water conforming to BS3978:1987, or water of equivalent purity. 4.2 Extraction solv
15、ents. Ethanol toluene azeotrope (ETA), formed by mixing7 volumes of ethanol with3 volumes of toluene, refluxing for1h over freshly ignited quicklime and then distilling, collecting the fractions of constant boiling point. Alternatively the azeotrope may be prepared by mixing7 volumes of absolute eth
16、anol with3volumes of toluene. 4.3 Solvent. Carbon tetrachloride. 4.4 Iodine monochloride solution. Dissolve30g of iodine monochloride in1l of carbon tetrachloride. Store the solution in an amber coloured bottle. 4.5 Potassium iodide solution. Dissolve75g of potassium iodide in water and dilute to500
17、ml. 4.6 Sodium thiosulfate solution, freshly standardized. Standard volumetric solution, C(Na 2 S 2 O 3 )=0.1mol/dm 3 . 4.7 Starch solution. Dissolve sufficient starch in hot water to prepare a1% solution. 4.8 Iodine indicator powder NOTEThis is an alternative to starch solution. 5 Apparatus 5.1 Gen
18、eral. Standard laboratory equipment. 5.2 Balance, accurate to0.1mg. 5.3 Extraction apparatus, as described in BS7164-3:1992. 5.4 Iodine flasks conforming to BS2735:1987. 5.5 Sintered filters conforming to grade P4 of BS1752:1983. 6 Sampling Sample raw rubber in accordance with BS6315:1993. 7 Prepara
19、tion of test sample Mill the test sample to as thin a sheet as possible. Extract the test sample in accordance with BS7164-3:1992. Dry the test sample to constant weight within 1mg. 8 Procedure 8.1 Test duplicate samples. Weigh, to the nearest0.1mg, a test sample of approximately0.25g. Place the tes
20、t sample in an iodine flask(5.4) and add50cm 3of carbon tetrachloride and shake or allow to stand until dissolved. If a gel is found to be present, remove by filtration through a sintered filter(5.5). Carefully evaporate the filtrate to dryness in a weighed dish and dry to constant mass, to within 1
21、mg, under vacuum at40 C. Determine the mass of the gel-free polymer, transfer to a clean iodine flask and redissolve in50cm 3of carbon tetrachloride. Add, from a burette,50cm 3of iodine monochloride solution(4.4) to the polymer solution, mix by swirling and place in darkness for(30 0.5)min at(23 2)
22、C.BS7164-11.2:1993 2 BSI 11-1999 Add40cm 3of potassium iodide solution(4.5), shake vigorously and titrate with sodium thiosulfate solution0.1 mol/dm 3(4.6). Shake thoroughly at intervals throughout the titration and after shaking wash the mixture from the stoppers and the neck of the flask down into
23、 the flask using a small quantity of distilled water. Continue the titration until the mixture has reached a straw colour, add a few drops of starch solution(4.7) and continue the titration to the end point, which is indicated by the disappearance of the blue colour. Alternatively, add0.2g to0.5g of
24、 an iodine indicator powder(4.8) to the polymer solution at the titration stage. Vigorously shake during the final stages of the titration to ensure that the liberated iodine is completely transferred to the aqueous phase. Ignore any reappearance of the blue colour more than10s after the end-point h
25、as been reached. 8.2 In parallel with the determination, carry out a blank test using the same quantities of reagents under the same operating conditions but omitting the test sample. 9 Calculation and expression of units The percentage of unsaturated butadiene in the rubber is calculated by the for
26、mula: 10 Repeatability Duplicate samples shall agree to 0.5% of the mean value obtained. 11 Test report The test report shall include the following information: a) reference to this British Standard; b) identification of the test sample; c) the mean of two results obtained; d) the date of the test.
27、where V 0 is the volume in cubic centimetres of sodium thiosulfate solution used to titrate the reagent blank solution; V is the volume in cubic centimetres of sodium thiosulfate solution used to titrate the test solution; C is the exact concentration, in moles per cubic decimetre, of sodium thiosul
28、fate used; m is the mass, in grams, of the test sample. If the sample is filtered, m is the mass of the dried gel-free polymer; 2.7 is a stoichiometric constant. 2.7V 0 V () m -C BS7164-11.2:1993 BSI 11-1999 List of references Normative references BSI standards publications BRITISH STANDARDS INSTITU
29、TION, London BS1752:1983, Specification for laboratory sintered or fritted filters including porosity grading. BS2735:1987, Specification for iodine flasks. BS3978:1987, Specification for water for laboratory use. BS6315:1993, Methods of sampling of and further preparative procedures for raw natural
30、 and synthetic rubber. BS7164, Chemical tests for raw and vulcanized rubber. BS7164-3:1992, Methods for determination of solvent extract. Informative references BSI standards publications BRITISH STANDARDS INSTITUTION, London BS903, Physical testing of rubber 1) . BS1673, Methods of test for raw rub
31、ber and unvulcanized compounded rubber 1) . BS5923, Methods for chemical analysis of rubber 1) . 1) Referred to in the foreword only.BS7164-11.2: 1993 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandar
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