1、BRITISH STANDARD BS5923-2: 1980 Methods for Chemical analysis of rubber Part2: EDTA titrimetric method for determination of zinc content of rubber products UDC 678.4:543.244.6:546.47BS5923-2:1980 This BritishStandard, having been prepared under the directionof the Rubber StandardsCommittee, waspubli
2、shed under the authorityof the Executive Boardand comes into effecton 30June1980 BSI12-1999 The following BSI references relate to the work on this standard: Committee reference RUC/37 Draft for comment78/55298 DC ISBN 0 580 11459 7 Cooperating organizations The Rubber Standards Committee, under who
3、se direction this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: British Association of Synthetic Rubber Manufacturers* British Rubber Manufacturers Association* Department of Industry (Chemicals and T
4、extiles) Medical Sterile Products Association Ministry of Defence* Plastics and Rubber Institute Rubber and Plastics Research Association of Great Britain* Rubber Growers Association Society of Motor Manufacturers and Traders Limited The Malaysian Rubber Producers Research Association* The organizat
5、ions marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this BritishStandard: Chemical Society, Analytical Division Electric Cable Makers Confederation Institution of Water Engineers and Scientists Nati
6、onal College of Rubber Technology Individual expert Amendments issued since publication Amd. No. Date of issue CommentsBS5923-2:1980 BSI 12-1999 i Contents Page Cooperating organizations Inside front cover Foreword ii 1 Scope and field of application 1 2 References 1 3 Principle 1 4 Reagents 1 5 App
7、aratus 2 6 Procedure 2 7 Expression of results 2 8 Test report 3 Publications referred to Inside back coverBS5923-2:1980 ii BSI 12-1999 Foreword This Part of BS5923 has been prepared under the direction of the Rubber Standards Committee. In the past, methods for the chemical analysis of different ty
8、pes of rubber were published, as appropriate, in the “B series” of BS903 “Methods of testing vulcanized rubber” and in BS1673 “Methods for testing raw rubber and unvulcanized compounded rubber”. However, in many cases the methods for the various types of material are very similar. In the work of Tec
9、hnical Committee45, Rubber and rubber products, of the International Organization for Standardization (ISO), this has led to the preparation of International Standards for methods for the chemical analysis of rubber of general applicability; in order to facilitate the adoption of these as BritishSta
10、ndards and to simplify the general presentation of methods for the chemical analysis of rubber, it has been decided to publish this new BritishStandard. As further Parts of BS5923 are published, they will replace any corresponding methods in BS903 and BS1673, so that the BS903 “B series” and the app
11、ropriate parts of BS1673 will eventually be withdrawn completely. This Part supersedes section4 of BS903-B13 “Determination of ash and zinc oxide”; the remaining sections of BS903-B13 are superseded by BS5923-1. This Part is based on ISO2454:1976, with the inclusion of some technical and editorial c
12、hanges in the text. The major changes are listed below and are indicated by a vertical line in the margin. The changes in clauses in4, 6.2 and6.3 have been proposed by the United Kingdom as amendments to the ISO text. The method described in BS903-B13 involved titration with EDTA solution but the pr
13、ocedure described in this revision differs substantially. Clause reference Textual change 6.1 In this BritishStandard, a reference to BS5923-1 has been substituted for the reference to ISO247:1978. BS5923-1 is identical with ISO247:1978. 4 In ISO2454:1976 some of the reagents are listed in a differe
14、nt order as follows: 4.11 EDTA (disodium salt) 4.12 Zinc chloride 4.13 Dithizone indicator 4.13 The note in this BritishStandard is not included in ISO2454:1976. 6.2 The instructions in the first paragraph have been extended. In ISO2454:1976, the end of the first paragraph reads:“add2ml of the sulph
15、uric acid(4.4) and ash in the muffle furnace(5.1), maintained at550 25 C. In the second sentence of the second paragraph, the words “in a fume cupboard” have been added after “Evaporate the hydrofluoric acid”. In the fourth sentence of the second paragraph, ISO2454:1976 refers, incorrectly, to the e
16、vaporation of “hydrochloric” acid. 6.3 In ISO2454:1976, the second sentence of the third paragraph begins, incorrectly, with the word “Acidity”.BS5923-2:1980 BSI 12-1999 iii A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are resp
17、onsible 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, pagesi toiv, pages1to4, an inside back cover and a back cover. This standard has been up
18、dated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS5923-2:1980 BSI 12-1999 1 1 Scope and field of application This BritishStandard specifies an EDTA titrimetric method for the determination of the zin
19、c content of all rubber products. Lead, magnesium, iron, titanium, antimony, silica, and silicates in the ash do not interfere. The method is not applicable, however, if cobalt is present. 2 References The titles of the publications referred to in this standard are listed on inside back cover. 3 Pri
20、nciple Incineration of a test portion and dissolution of the ash in hydrochloric acid. Extraction of silica by treatment with hydrofluoric and sulphuric acids. Addition of aluminium chloride and aluminium fluoride to precipitate calcium and magnesium as hexafluoroaluminates. Fluoride complexes iron,
21、 titanium and excess aluminium (interference from large amounts of iron is further reduced by addition of2,4-pentanedione). Titration of the zinc with an EDTA (disodium salt) standard volumetric solution in the presence of dithizone as indicator. 4 Reagents During the analysis, use only reagents of
22、recognized analytical grade, and only distilled water or water of equivalent purity. All recognized health and safety precautions must be observed in the handling of chemicals listed and in performing the analysis. 4.1 Acetone 4.2 2,4-Pentanedione,10%(V/V) solution in the acetone(4.1). 4.3 Hydrochlo
23、ric acid ( 1.18g/ml). 4.4 Sulphuric acid ( 1.84g/ml). 4.5 Hydrofluoric acid,48%(m/m) solution. 4.6 Ammonium hydroxide solution ( 0.01g/ml). 4.7 Buffer solution. Dissolve60g of acetic acid (CH 3 COOH) and77g of ammonium acetate (CH 3 COONH 4 ) in water and dilute to1000ml 1)with water. 4.8 Aluminium
24、chloride,0.1M solution. Dissolve2.42g of aluminium chloride hexahydrate (AlCl 3 .6H 2 O) in water and dilute to100ml with water. 4.9 Magnesium chloride,0.1M solution. Dissolve2.03g of magnesium chloride hexahydrate (MgCl 2 .6H 2 O) in water and dilute to100ml with water. 4.10 Ammonium fluoride,3M so
25、lution. Dissolve55.5g of ammonium fluoride (NH 4 F) in water and dilute to500ml with water. Store in a polyethylene or wax-coated bottle. 4.11 Zinc chloride, standard solution. Calcine zinc oxide in a porcelain crucible for2h in the furnace(5.1), maintained at550 25 C, and cool in a desiccator. Diss
26、olve about1.0g of the dried reagent, weighed to the nearest0.0001g, in50ml of water and20ml of the hydrochloric acid(4.3). Transfer to a1000ml volumetric flask and dilute to the mark with water. 4.12 Dithizone indicator. Dissolve0.01g of dithizone (phenylazo)thioformic acid,2-phenylhydrazide in10ml
27、of the acetone(4.1). Prepare a fresh solution every48h. 4.13 (Ethylenedinitrilo)tetraacetic acid disodium salt, dihydrate (ECTA disodium salt),0.01M standard volumetric solution. NOTEThis solution should be prepared and standardized as described in4.13.1 to4.13.3. Standard solutions purchased from r
28、eagent suppliers may contain mercury salts, added as preservative, which will interfere with the dithizone indicator and possibly mask the end-point. 4.13.1 Preparation. Dissolve3.72g of EDTA (disodium salt) in water and dilute to1000ml with water. 4.13.2 Standardization. Pipette25ml of the standard
29、 zinc chloride solution(4.11) into a250ml conical flask. Add5ml of the hydrochloric acid(4.3) and proceed according to6.3 beginning with “add2ml of the aluminium chloride solution”. Carry out the titration as described in6.4, using the50ml burette(5.3). 4.13.3 Standardization factor. The standardiza
30、tion factor, T, of the EDTA (disodium salt) solution, expressed as grams of zinc oxide (ZnO) per millilitre, is given by the formula where m 1is the mass, in grams, of dried zinc oxide used in the preparation of the standard zinc chloride solution(4.11); V 1is the volume, in millilitres, of EDTA (di
31、sodium salt) solution used in the titration of the standard zinc chloride solution(4.11). 4.14 Universal indicator paper 1) The term millilitre (ml) is commonly used for the cubic centimetre (cm 3 ), particularly to denote the capacity of laboratory glassware. Apparatus with either type of marking i
32、s satisfactory to use with this BritishStandard. T m 1 40 V 1 - =BS5923-2:1980 2 BSI 12-1999 5 Apparatus Ordinary laboratory apparatus and 5.1 Muffle furnace, capable of being controlled at550 25 C. 5.2 Burette, of capacity10ml, graduated in0.02ml divisions. 5.3 Burette, of capacity50ml, graduated i
33、n0.1ml divisions. 5.4 Platinum crucibles, of capacity50ml. 6 Procedure 6.1 Weigh, to the nearest0.0001g, approximately1g of the sample. Place this test portion in one of the platinum crucibles(5.4) and reduce to ash according to method C specified in BS5923-1. Cool the crucible and add approximately
34、50ml of the hydrochloric acid(4.3). Transfer the contents of the crucible to a250ml beaker with approximately50ml of water. Break up any large cakes of ash with a glass stirring rod. If any insoluble residue is present after cooling, proceed in accordance with6.2. If no insoluble material is present
35、, proceed in accordance with6.3. 6.2 Filter the residue through an ashless filter paper. Retain the filtrate. Place the insoluble residue and the filter paper into a second platinum crucible(5.4), add2ml of the sulphuric acid(4.4) and then heat over a gas burner to volatilize the excess sulphuric ac
36、id. Transfer the crucible and its contents to the muffle furnace, maintained at550 25 C, and heat until all the carbon is completely oxidized and a clean ash is obtained. Moisten the residue with5 to10 drops of the sulphuric acid(4.4) and5ml of the hydrofluoric acid solution(4.5). Evaporate the hydr
37、ofluoric acid in a fume cupboard and stop heating as soon as the evolution of white fumes indicates sulphuric acid decomposition. When cool, add an additional5 to10 drops of the sulphuric acid and5ml of the hydrofluoric acid solution. Repeat the evaporation of the hydrofluoric acid and add1ml of the
38、 sulphuric acid and5ml of the hydrofluoric acid solution to the wet residue. Evaporate the hydrofluoric acid and stop heating as soon as white fumes appear. Pour the contents of the crucible carefully into the retained filtrate, wash the crucible with distilled water and add the washings to the filt
39、rate. Proceed according to6.3. 6.3 If necessary, evaporate the solution or filtrate to a volume of approximately50ml. Transfer the cooled solution to a100ml volumetric flask and make up to the mark with distilled water. Select an aliquot portion from the following table according to the expected zin
40、c content and transfer to a250ml conical flask. If necessary, dilute the aliquot portion to25ml, add2ml of the aluminium chloride solution(4.8),5ml of the magnesium chloride solution(4.9), and10ml of the ammonium fluoride solution(4.10). Add ammonium hydroxide solution(4.6) until alkaline to the uni
41、versal indicator paper(4.14). Acidify with approximately1ml of the sulphuric acid(4.4). Bring the solution to the boil, and then cool to room temperature. Add ammonium hydroxide solution(4.6) until just alkaline. Thenadd an additional0.5ml. Add10ml of the buffer solution(4.7),60ml of the acetone(4.1
42、),5ml of the2,4-pentanedione solution(4.2) and5 drops of the dithizone indicator solution(4.12). Cool the solution in an ice bath. 6.4 Titrate with the EDTA (disodium salt) standard volumetric solution(4.13), using the appropriate burette indicated in the table. The end-point is reached at a yellow-
43、green colour, which does not change on the addition of a further drop of the EDTA (disodium salt) standard volumetric solution. 7 Expression of results The zinc content of the test portion, expressed as a percentage by mass of zinc oxide (ZnO), is given by the formula where T is the standardization
44、factor as calculated in4.13.3; V 2is the volume, in millilitres, of the EDTA (disodium salt) standard volumetric solution(4.13) used in the titration of the aliquot portion of the test solution; V 3is the volume, in millilitres, of the aliquot portion; m 2is the mass, in grams, of the test portion.
45、ZnO expected Aliquot portion Capacity of burette to be used % (m/m) 0 to3 3 to8 more than8 ml 25 10 10 ml 10(5.2) 10(5.2) 50(5.3) TV 2 100 100 V 3 m 2 -BS5923-2:1980 BSI 12-1999 3 8 Test report The test report shall include the following particulars: a) a reference to this BritishStandard; b) the re
46、sults and the method of expression used; c) any unusual features noted during the determination; d) any operation not included in this BritishStandard or in the BritishStandard to which reference is made, or regarded as optional.4 blankBS5923-2:1980 BSI 12-1999 Publications referred to BS903, Method
47、s of testing vulcanized rubber 2) . BS1673, Methods for testing raw rubber and unvulcanized compounded rubber 2) . BS5923, Methods for chemical analysis of rubber. BS 5923-1, Determination of ash. ISO247, Rubber Determination of ash 2) . ISO2454, Rubber products Determination of zinc content EDTA ti
48、trimetric method 2) . 2) Referred to in the foreword only.BS5923-2: 1980 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 international le
49、vel. 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 the technical committee responsible, the identity of which can be found
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