1、BRITISH STANDARD BS ISO 9028:2006 Rubber Dissolution by acid digestion ICS 83.060 BS ISO 9028:2006 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 October 2006 BSI 2006 ISBN 0 580 49438 7 National foreword This British Standard was publish
2、ed by BSI. It is the UK implementation of ISO 9028:2006. It supersedes BS 7164-4:1990 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee PRI/23, Test methods for rubber and non-black compounding ingredients. A list of organizations represented on PRI/23
3、can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publicati
4、on Amd. No. Date CommentsINTERNATIONAL STANDARD ISO 9028 Second edition 2006-09-15 Reference number ISO 9028:2006(E) Rubber Dissolution by acid digestion Caoutchouc Dissolution par attaque acideBS ISO 9028:2006ii iii Foreword ISO (the International Organization for Standardization) is a worldwide fe
5、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
6、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. International Standards are drafted in accord
7、ance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard require
8、s approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 9028 was prepared by Technical C
9、ommittee ISO/TC 45, Rubber and rubber products, Subcommittee SC 2, Testing and analysis. This second edition cancels and replaces the first edition (ISO 9028:1989), which has been revised to update the normative references. BS ISO 9028:2006blank1 Rubber Dissolution by acid digestion WARNING Persons
10、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 of the user to establish appropriate safety and health practices and to ensure complia
11、nce with any national regulatory conditions. 1S c o p e This International Standard specifies methods for disintegration of raw rubber and rubber products by nitric acid or by a mixture of nitric and sulfuric acids. This International Standard is generally applicable, but is essential where potentia
12、lly volatile elements or combinations of elements are present (i.e. As, Sb, Bi, and Zn Cl, Cu Cl and Pb Cl). It is useful in these cases because lower temperatures are involved which result in less loss by volatilization. These methods will be used in order to produce solutions for the determination
13、 of metals, for example as traces, if the application of ISO 247 is not advisable. These methods prevent loss of volatile metal derivatives and the formation of insoluble metal silicates (which may result during dry ashing of halogenated rubbers containing zinc or of rubbers filled with silica). 2 N
14、ormative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 124, Latex, rubber Determ
15、ination of total solids content ISO 247, Rubber Determination of ash ISO 1042, Laboratory glassware One-mark volumetric flasks ISO 1795, Rubber, raw natural and raw synthetic Sampling and further preparative procedures 3 Principle 3.1 Method A Sulfuric acid digestion followed by nitric acid oxidatio
16、n carried out in open flasks. Treatment with sulfuric and hydrofluoric acids in order to volatilize any silicon as silicon fluoride and to form metal sulfates is necessary if silicon or silicates are present. 3.2 Method B Dissolution of the rubber with nitric acid in a polytetrafluoroethylene-coated
17、 pressure vessel. + + + BS ISO 9028:20062 Treatment with sulfuric and hydrofluoric acids in order to volatilize any silicon as silicon fluoride and to form metal sulfates is necessary if silicon or silicates are present. 4R e a g e n t s WARNING All recognized health and safety precautions shall be
18、observed during the handling of these reagents. During the analysis, use only reagents of recognized extra-high-purity analytical grade, and only distilled water or water of equivalent purity. 4.1 Sulfuric acid, . 4.2 Hydrochloric acid, . 4.3 Hydrochloric acid, diluted . Dilute 1 volume of concentra
19、ted hydrochloric acid (4.2) with 2 volumes of water. 4.4 Hydrofluoric acid, ( to by mass). 4.5 Nitric acid, . 4.6 Hydrogen peroxide, (by mass) solution. 5 Apparatus Ordinary laboratory apparatus, plus the following: 5.1 Balance, accurate to . 5.2 One-mark volumetric flask, glass-stoppered, of capaci
20、ty , classA, complying with the requirements of ISO 1042. 5.3 Platinum crucible, of capacity . 5.4 Platinum rod, as stirrer. 5.5 Electric heating plate or gas burner with sand bath. 5.6 Kjeldahl flask, of capacity . 5.7 Filter funnel, of diameter . 5.8 Pipettes, of capacity , , and , respectively. T
21、he pipette shall be of plastic, not glass, since it is to hold hydrofluoric acid. 5.9 Pressure vessel, non-magnetic, made of high-quality stainless steel, of capacity to , wall- coated with polytetrafluoroethylene, with a magnetic stirrer bar (also coated) and a thermometer. 5.10 Electric hotplate,
22、fitted with a magnetic rotor. 6 Sample preparation At all stages of sample preparation, take care to avoid contamination. For the determination of metal in rubber, cut at least of rubber from the sample, if necessary from more than one place, so that proper representation of the whole sample is achi
23、eved. Treat the piece or pieces comprising 20 = 1,84 Mg/m 3 20 = 1,18 Mg/m 3 1 + 2 20 = 1,12 Mg/m 3 38 % 40 % 20 = 1,42 Mg/m 3 38 % 0,1 mg 100 cm 3 50 cm 3 250 cm 3 65 mm 1cm 3 5cm 3 10 cm 3 20 cm 3 5cm 3 20 cm 3 50 cm 3 2g BS ISO 9028:20063 the test portion in accordance with ISO 1795. Alternativel
24、y, for finished products prepare the test portion by cutting the rubber into small portions each weighing approximately . For the determination of metal in latex, take from the sample a portion of thoroughly mixed latex containing at least of total solids and dry to constant mass as specified in ISO
25、 124. Digestion of this portion can be facilitated by thinly sheeting it by passing it six times between the tightly closed cold rolls of a laboratory mill, rolling the rubber into a cylinder after each pass and presenting the cylinder end on to the rolls for the next pass. 7 Procedures 7.1 General
26、The digestion shall be conducted in a well ventilated hood or digestion rack so that acid fumes do not enter the laboratory working space. 7.2 Method A Digestion in open flasks 7.2.1 Place a test portion (see Clause 6) weighing at least , weighed to the nearest , in the Kjeldahl flask (5.6), add of
27、sulfuric acid (4.1) and heat moderately until the test portion has disintegrated. Carefully add of nitric acid (4.5). If the reaction becomes too vigorous, cool the flask in a beaker of cold water and store at room temperature for at least before reheating. Some rubbers cause considerable splashing;
28、 in this case, restart the procedure using a larger flask, decompose with sulfuric acid and cool before adding nitric acid. Store the mixture for a longer time, for example overnight, before heating with the nitric acid. As soon as the initial reaction has subsided, heat the mixture gently until the
29、 vigorous reaction has ceased, and then more strongly until the mixture darkens. Add a portion of nitric acid (4.5) and heat until darkening takes place. Continue this treatment until the solution becomes colourless or pale yellow and fails to darken on further heating. If the digestion is prolonged
30、, it may be necessary to add about of sulfuric acid to prevent the contents of the flask from solidifying. 7.2.2 If the digest is free from insoluble matter, cool, add of hydrogen peroxide solution (4.6) and 2 drops of nitric acid (4.5) and heat to fuming. Repeat the addition and heating until there
31、 is no further reduction in the colour of the solution. Cool, dilute with of water and heat to fuming. Finally, cool the solution and add of diluted hydrochloric acid (4.3). Transfer the acid digest to the volumetric flask (5.2), rinse the Kjeldahl flask with three portions of water and add to the v
32、olumetric flask. Dilute to the mark with water. 7.2.3 If the digest contains insoluble matter, cool it and transfer it with the residue to the platinum crucible (5.3), rinsing with three portions of water. Evaporate to dryness, and then ignite until all the carbon has burnt off. Certain metals, such
33、 as mercury and arsenic, might be volatilized and lost. Therefore, for these metals, do not ignite to complete dryness. Cool, add a few drops of sulfuric acid (4.1) and of hydrofluoric acid (4.4). Evaporate to dryness on the heating device (5.5) while stirring with the platinum rod (5.4). Repeat thi
34、s procedure twice. Cool the crucible plus residue and add of diluted hydrochloric acid (4.3). If the solution is clear, transfer it to the volumetric flask (5.2), rinsing with three portions of water. Dilute to the mark with water. If the solution is not clear, filter into the volumetric flask (5.2)
35、. Rinse the crucible five times with a portion of water, and pour each over the filter into the volumetric flask. Dilute to the mark with water. 0,1 g 2g 2g 2mg 10 cm 3 5cm 3 2h 1cm 3 1cm 3 0,5 cm 3 10 cm 3 20 cm 3 5cm 3 5cm 3 5cm 3 20 cm 3 5cm 3 5cm 3 BS ISO 9028:20064 7.3 Method B Digestion in a p
36、ressure vessel WARNING During use, the pressure vessel shall be placed behind a suitable protective screen. 7.3.1 Place a test portion (see Clause 6) of about , weighed to the nearest , in the pressure vessel (5.9). Add the magnetic stirrer bar and rinse with of sulfuric acid (4.1) and of nitric aci
37、d (4.5). Close the pressure vessel in accordance with the manufacturers instructions. Insert the thermometer. Place the pressure vessel on the hotplate with magnetic rotor (5.10). Heat the plate to to , starting the magnetic rotor at the same time. Continue stirring the pressure vessel at the indica
38、ted temperature for . Allow the pressure vessel to cool to room temperature. Wipe the pressure vessel dry and open it. 7.3.2 In most cases, the rubber will be found to be completely dissolved. If it is not, proceed in accordance with 7.2.3 in an open crucible. 100 mg 0,2 mg 5cm 3 3cm 3 135 C 145 C 2
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