1、BRITISH STANDARD BS 7164-25: 1996 ISO 8054:1996 Chemical tests for raw and vulcanized rubber Part 25: Method for determination of sulfide sulfur content ICS 83.040.10; 83.060BS7164-25:1996 This British Standard, having been prepared under the directionof the Sector Board forMaterials and Chemicals,
2、waspublished under the authorityof the Standards Boardand comes into effect on 15June 1996 BSI 07-1999 First published July 1990 Second edition June 1996 The following BSI references relate to the work on this standard: Committee reference PRI/23 Draft for comment 94/306089 DC ISBN 0 580 25901 3 Com
3、mittees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee PRI/23, Chemical testing of rubbers, upon which the following bodies were represented: Malaysian Rubber Producers Research Association Ministry of Defence RAPRA Technology Ltd.
4、 Royal Society of Chemistry Amendments issued since publication Amd. No. Date CommentsBS7164-25:1996 BSI 07-1999 i Contents Page Committees responsible Inside front cover National foreword ii Introduction 1 1 Scope 1 2 Normative references 1 3 Principle 1 4 Reagents and materials 1 5 Apparatus 1 6 S
5、ampling, sample preparation and selection of test portion 2 7 Procedure 3 8 Expression of results 3 9 Test report 3 Figure 1 Extraction apparatus 2 Figure 2 Typical apparatus for the evolution and absorption of hydrogen sulfide 4 List of references Inside back coverBS7164-25:1996 ii BSI 07-1999 Nati
6、onal foreword This Part ofBS7164 has been prepared by Technical Committee PRI/23 and is identical withISO8054:1996 Rubber, compounded or vulcanized Determination of sulfide sulfur content Iodometric method, published by the International Organization for Standardization (ISO). It supersedes BS7164-2
7、5:1990 which is withdrawn.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 legal obligations. Cross-referenc
8、es International standard Corresponding British Standard ISO 383:1976 BS 572:1985 Specification for interchangeable conical ground glass joints (Technically equivalent) ISO 1407:1992 BS 7164 Chemical tests for raw and vulcanized rubber Part 3:1992 Methods for determination of solvent extract (Identi
9、cal) ISO 4793:1980 BS 1752:1983 Specification for laboratory sintered or fritted filters including porosity grading (Identical) ISO 4799:1978 BS 5922:1980 Specification for glass condensers for laboratory use (Identical) Summary of pages This document comprises a front cover, an inside front cover,
10、pages i and ii, pages1 to 4, 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 amendment table on the inside front cover.BS7164-25:1996 BSI 07-1999 1 Introduction In unvulcanized compound
11、ed rubbers, any sulfide sulfur present is normally due to metallic sulfides contained in fillers (e.g.lithopone). In vulcanizates, the sulfide sulfur content increases with the state of cure and can therefore be used as a method of determining the state of cure of products for which this is critical
12、, providing no metallic sulfide fillers are present in large amounts. WARNING Persons using this International Standard should be familiar with normal laboratory practice. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility
13、of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. 1 Scope This International Standard specifies a titrimetric method for the determination of sulfide sulfur in unvulcanized compounded rubbers and in vulcanizates. It is
14、applicable to chlorinated rubbers, nitrile rubbers and hydrocarbon rubbers (including natural rubber). 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editio
15、ns indicated were 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 editions of the standards indicated below. Members of IEC and ISO maintain registers of currently v
16、alid International Standards. ISO 383:1976, Laboratory glassware Interchangeable conical ground joints. ISO 1407:1992, Rubber Determination of solvent extract. ISO 4793:1980, Laboratory sintered (fritted) filters Porosity grading, classification and designation. ISO 4799:1978, Laboratory glassware C
17、ondensers. 3 Principle The rubber is extracted with acetone and the extracted rubber is treated with a mixture of hydrochloric and acetic acids to decompose metallic sulfides. The resulting hydrogen sulfide is absorbed in buffered cadmium acetate solution and the cadmium sulfide thus formed is deter
18、mined iodometrically. 4 Reagents and materials During the analysis, only reagents of recognized analytical grade shall be used and only distilled water or water of equivalent purity. 4.1 Acetone 4.2 Hydrochloric acid/acetic acid, mixture. Mix together5volumes of glacial acetic acid ( = 1,05 g/cm 3 )
19、,1volume of concentrated hydrochloric acid 36%(m/m), =1,18 g/cm 3 and1volume of water. 4.3 Cadmium acetate, buffered solution. Dissolve25g of cadmium acetate dihydrate (CH 3 COO) 2 Cd2H 2 O and25g of sodium acetate trihydrate (CH 3 COONa3H 2 O) in water, add100cm 3of glacial acetic acid ( =1,05g/cm
20、3 ) and make up to1dm 3with water. 4.4 Surfactant, solution. Make up an approximately2% (m/m) aqueous solution of a surfactant which will not react with iodine. Filter the solution through a No.1 Whatman 1) , or equivalent, filter paper before use. NOTE 1Gum ghatti and nonyl phenol polyethoxalate ar
21、e examples of suitable surfactants. 4.5 Iodine, solution, c(I 2 ) 0,025 mol/dm 3 . Dissolve6,35g of iodine and40g of potassium iodide in water, and make up to1dm 3 . 4.6 Sodium thiosulfate, standard volumetric solution, c(Na 2 S 2 O 3 5H 2 O)=0,05mol/dm 3 . 4.7 Starch, solution,1g in100cm 3of water.
22、 4.8 Supply of pure nitrogen gas 4.9 Glycerol 5 Apparatus Ordinary laboratory apparatus, and 5.1 All-glass extraction apparatus (see Figure 1), as specified inISO1407, comprising the elements described in 5.1.1 to 5.1.3. 5.1.1 Extraction flask, capacity150cm 3 , with a 34/35 socket conforming with t
23、he requirements ofISO383 (seealso5.2.1). 1) No. 1 Whatman is an example of a suitable product available commercially. This information is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO of this product.BS7164-25:1996 2 BSI 07-1999 5.1.2
24、 Jacketed Soxhlet extractor, preferably with a34/35 socket and34/35 cone. 5.1.3 Graham condenser, coolant-tube length400mm, with a34/35 angle drip cone conforming with the requirements ofISO4799. Substitutions may be made if they perform the same function as the item listed. 5.2 All-glass apparatus
25、for the evolution and absorption of hydrogen sulfide (seeFigure 2), comprising the elements described in 5.2.1 to 5.2.8. 5.2.1 Extraction flask (A), capacity150cm 3 , with a34/35 socket conforming with the requirements ofISO383 (see also 5.1.1). 5.2.2 Adapter (D), with14/23 socket and34/35 cone, and
26、 with a gas inlet tube to reach to within3mm of the bottom of the extraction flask (5.2.1) when assembled. 5.2.3 Conical flask (J), of capacity250cm 3 , with a24/29 socket. 5.2.4 Gas-washing bottles (K and L) 5.2.5 Receiver adapter (E), with10/19 socket and24/29 cone, and with an internal sealed dip
27、-tube. 5.2.6 Condenser, Liebig type (F), effective coolant-tube length approximately250mm, with14/23 angle drip cone,14/23 socket and side arm with10/19 cone. 5.2.7 Dropping funnel (G), capacity100cm 3 , with14/23 cone, modified stem and14/23 stopper. 5.2.8 Micro-immersion filter (Emich pattern) (H)
28、, stem approximately75mm long, diameter of disc10mm, porosity gradeP40 (seeISO4793). 6 Sampling, sample preparation and selection of test portion 6.1 Cut from several areas of the sample a test portion of between 0,5 g and2,0g, depending on the expected sulfide sulfur level. 6.2 Pass the test portio
29、n six times between the cold rolls of a laboratory mill set to a nip not exceeding0,5mm. If it is not possible to pass the test portion through the mill, the test portion may be cut into pieces less than1mm per side. Weigh the test portion to the nearest 1mg. 6.3 Extract the test portion with aceton
30、e (4.1) in the extraction apparatus (5.1) as described inISO1407. 6.4 Transfer the extracted test portion from the Soxhlet extractor (5.1.2) to a clock glass and evaporate the acetone by heating in an oven for15min at70 C. Transfer the dried sample to the150cm 3flask (A). Figure 1 Extraction apparat
31、usBS7164-25:1996 BSI 07-1999 3 7 Procedure 7.1 Determination 7.1.1 Assemble the flask (A) into the apparatus of Figure 2, ensuring that all ground glass joints are lubricated with glycerol (4.9). Introduce100cm 3of cadmium acetate solution (4.3) and1cm 3of surfactant solution (4.4) into the conical
32、flask (J) and half fill the gas-washing bottles (K and L) with the cadmium acetate solution. Pass a stream of nitrogen (4.8) through the apparatus to displace the air and then adjust the flow to about one bubble per second in the conical flask (J). 7.1.2 Introduce50cm 3of the hydrochloric acid/aceti
33、c acid mixture (4.2) slowly from the dropping funnel (G) into the flask (A), heat slowly to boiling and continue to boil gently for30min to40min. Towards the end of this period, increase the flow of nitrogen to sweep over all traces of hydrogen sulfide. The solution in bottle K should be clear and c
34、olourless; if this is not so, it is an indication that the nitrogen flow has been too rapid and the determination shall be repeated using a smaller test portion or slower rate of nitrogen flow. Disconnect the receiver adapter (E) from the delivery tube and, holding it at an angle, add by means of a
35、pipette a measured volume V 0of the iodine solution (4.5) (usually25cm 3is a suitable quantity) to flask J, so that excess iodine is present. 7.1.3 Allow the iodine to react with any precipitate adhering to the entry tube and, when all the precipitate has dissolved, remove and rinse the tube, cool t
36、he solution to15 C, and titrate the excess iodine with the sodium thiosulfate solution(4.6), using starch solution (4.7) as indicator. Record the volume V 1of sodium thiosulfate solution used. 7.2 Blank titration Carry out, in parallel with the determination described in 7.1, a blank titration by ti
37、trating V 0 cm 3of the iodine solution with the sodium thiosulfate solution in the presence of100cm 3of the cadmium acetate solution (4.3), using starch solution as indicator. Record the volume V 2of sodium thiosulfate solution used. 8 Expression of results Calculate the sulfide sulfur content, expr
38、essed as the percentage of S by mass, from the formula where The test result shall be the mean, rounded to one decimal place, of two determinations. 9 Test report The test report shall include the following information: a) a reference to this International Standard; b) all details necessary for the
39、identification of the sample; c) the results and the units in which they are expressed; d) any unusual features noted during the determination; e) any operation not specified in this International Standard or in the International Standards to which reference is made, and any operation regarded as op
40、tional; f) the date of the test. V 1 is the volume, in cubic centimetres, of the sodium thiosulfate solution (4.6) used in the titration described in 7.1.3; V 2 is the volume, in cubic centimetres, of the sodium thiosulfate solution (4.6) used in the blank titration described in 7.2; c is the actual
41、 concentration, in moles of Na 2 S 2 O 3 5H 2 O per cubic decimetre, of the sodium thiosulfate solution (4.6); m is the mass, in grams, of the test portion(6.1). 1,6V 2 V 1 ()c m -BS7164-25:1996 4 BSI 07-1999 Figure 2 Typical apparatus for the evolution and absorption of hydrogen sulfideBS7164-25:19
42、96 BSI 07-1999 List of references See national foreword.BS 7164-25: 1996 ISO 8054:1996 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in Europe and at the in
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