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1、BRITISH STANDARD BS 7164-5: 1991 ISO 247:1990 Chemical tests for raw and vulcanized rubber Part 5: Methods for determination of ash content Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 14:33:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7164-5:1991 This Br
2、itish Standard, having been prepared under the direction of the Plastics and Rubber Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 31 May 1991 BSI 10-1999 The following BSI references relate to the work on this standard: Committee refere
3、nce PRM/23 Draft for comment 88/35376 DC ISBN 0 580 19641 0 Committees responsible for this British Standard The preparation 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 repres
4、ented: Institute of Water and Environmental Management Laboratory of the Government Chemist Ministry of Defence Royal Society of Chemistry Rubber and Plastics Research Association Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank
5、University, Fri Dec 08 14:33:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7164-5:1991 BSI 10-1999i Contents Page Committees responsibleInside front cover National forewordii 1Scope1 2Normative references1 3Principle1 4Reagent1 5Apparatus1 6Preparation of the test portion1 7Procedure2 8Expression
6、 of results2 9Test report3 Publication(s) referred toInside back cover Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 14:33:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7164-5:1991 ii BSI 10-1999 National foreword This Part of BS 7164 has been prepared unde
7、r the direction of the Plastics and Rubber Standards Policy Committee and is identical with ISO 247:1990 “Rubber Determination of ash”, published by the International Organization for Standardization (ISO). BS 7164 rationalizes all the methods that deal with chemical analysis of raw, compounded and
8、vulcanized rubber, some of which have previously been published in BS 903, BS 1673 and BS 5923. Relevant Parts of those standards will be withdrawn or deleted by amendment, as appropriate, when superseded by Parts and Sections of BS 7164. This Part of BS 7164 supersedes BS 5923-1:1980 which is withd
9、rawn. The Technical Committee has reviewed the provisions of ISO 248:1979 and ISO 1629:1987, to which reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. A British Standard does not purport to include all the necessary provisions of a co
10、ntract. 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-reference International StandardCorresponding British Standard ISO 1796:1982BS 6315:1982 Methods for sampling and samp
11、le preparation of raw rubber (Technically equivalent) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 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
12、 will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 14:33:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7164-5:1991 BSI 10-19991 1 Scope 1.1 This International Standard specifies two methods for
13、 the determination of ash from raw rubbers, compounded rubbers and vulcanizates. The methods are applicable to raw, compounded or vulcanized rubbers of the M, N, O, R and U families described in ISO 1629, except as restricted in 1.2 and 1.3 below. This International Standard does not cover the inter
14、pretation of the ash results as to the inorganic chemical content of a compound or vulcanizate. This is the responsibility of the analyst, who has to be aware of the behaviour of rubber additives at elevated temperatures. 1.2 Method A shall not be used for the determination of ash from compounded or
15、 vulcanized rubbers containing chlorine, bromine or iodine. 1.3 Method B shall be used for compounded or vulcanized rubbers containing chlorine, bromine or iodine. It shall not be used for uncompounded rubbers. 1.4 Lithium and fluorine compounds may react with silica crucibles to form volatile compo
16、unds, giving low ash results. Platinum crucibles shall be used for ashing fluorine-containing and lithium-polymerized rubbers. 1.5 The two methods of ashing do not give identical results in all cases, and it is necessary to state in the test report the method of ashing employed. 2 Normative referenc
17、es The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Stand
18、ard 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 valid International Standards. ISO 248:1979, Rubbers, raw Determination of volatile matter content. ISO 1629:1987, Rubber an
19、d latices Nomenclature. ISO 1796:1982, Rubber, raw Sample preparation. 3 Principle 3.1 Method A A weighed test portion is heated in a crucible over a gas burner. After expulsion of the volatile decomposition products, the crucible is transferred to a muffle furnace where it is heated until all the c
20、arbonaceous matter has been burnt off and constant mass is attained. 3.2 Method B A weighed test portion is heated in a crucible in the presence of sulfuric acid, first by means of a gas burner and then in a muffle furnace until all the carbonaceous matter has been burnt off and constant mass is att
21、ained. 4 Reagent Sulfuric acid (for method B only), analytical grade, 1,84 g/cm3. 5 Apparatus Ordinary laboratory apparatus and the following: 5.1 Crucible, of porcelain, silica or platinum, of capacity approximately 50 cm3. For raw synthetic rubbers, it is permitted to use a crucible of minimum cap
22、acity 25 cm3 per gram of test portion. 5.2 Heat-resistant, thermally insulating board, 100 mm square and of thickness approximately 5 mm, with a central hole to accommodate the crucible (5.1). About two-thirds of the crucible shall project below the board. 5.3 Bunsen burner, or similar type of gas b
23、urner. 5.4 Muffle furnace, fitted with a flue and with provision for controlling the air flow through the furnace. (This may be achieved by adjusting the door opening.) A temperature-controlling device is required to maintain a temperature of 550 C 25 C or 950 C 25 C. 6 Preparation of the test porti
24、on 6.1 Test portions of raw natural rubber shall be cut from the homogenized piece prepared in accordance with ISO 1796. Test portions of raw synthetic rubbers shall be cut from the dried rubber obtained after carrying out the determination of volatile matter content in accordance with ISO 248. 6.2
25、Test portions of rubber compounds shall be comminuted by hand. 6.3 Test portions of vulcanizates shall be sheeted or crumbed on a mill or comminuted by hand. 6.4 Care shall be taken to ensure that test portions of rubber compounds and vulcanizates are representative of the sample. Licensed Copy: Lon
26、don South Bank University, London South Bank University, Fri Dec 08 14:33:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7164-5:1991 2 BSI 10-1999 7 Procedure 7.1 Method A Heat the clean empty crucible (5.1) of appropriate size for about 30 min in the muffle furnace (5.4), maintained at 550 C 25 C
27、, allow to cool to ambient temperature in a desiccator and weigh to the nearest 0,1 mg. Take a test portion of about 5 g of raw rubber or 1 g to 5 g of compounded rubber or vulcanizate, according to the mass of ash to be expected, and weigh to the nearest 0,1 mg. Place the weighed test portion in th
28、e crucible mounted in the hole in the heat-resistant, thermally insulating board (5.2). Heat the crucible gently with the burner (5.3) in a hood for proper ventilation, taking care that the rubber does not ignite. If any material is lost due to spurting or frothing, repeat the above procedure with a
29、 new test portion. When the rubber has decomposed to a charred mass, gradually increase the heat from the burner until the volatile decomposition products have been substantially expelled and a dry carbonaceous residue remains. Transfer the crucible and its contents to the muffle furnace, maintained
30、 at 550 C 25 C (see, however, the note), leaving the door of the furnace slightly open to provide sufficient air to oxidize the carbon. Continue heating until the carbon is completely oxidized and a clean ash is obtained. Remove the crucible and its contents from the furnace, allow to cool to ambien
31、t temperature in the desiccator and weigh to the nearest 0,1 mg. Then heat the crucible and its contents again for about 30 min in the muffle furnace, maintained at 550 C 25 C (or 950 C 25 C see the note), allow to cool to ambient temperature in the desiccator and re-weigh to the nearest 0,1 mg. Thi
32、s mass shall not differ from the previous mass by more than 1 mg in the case of raw rubbers or by more than 1 % relative to the amount of ash for compounds and vulcanizates. If this requirement is not fulfilled, repeat the heating, cooling and weighing procedure until the difference between two succ
33、essive weighings meets this requirement. NOTEFor compounds and vulcanizates, a temperature of 950 C 25 C may be used. 7.2 Method B Heat the clean empty crucible (5.1) of appropriate size for about 30 min in the muffle furnace (5.4), maintained at 950 C 25 C, allow to cool to ambient temperature in a
34、 desiccator and weigh to the nearest 0,1 mg. Take a test portion of about 1 g to 5 g of the compound or vulcanizate and weigh to the nearest 0,1 mg. Place the test portion in the crucible and pour about 3,5 cm3 of the concentrated sulfuric acid (clause 4) over it so that the rubber is completely wet
35、ted. Place the crucible and its contents in the hole in the heat-resistant, thermally insulating board (5.2) and heat gently with the burner in a hood for proper ventilation. If, during the initial reaction, the mixture swells excessively, withdraw the flame to avoid possible loss of material. When
36、the reaction becomes more gentle, increase the heat from the burner until the excess sulfuric acid is volatilized and a dry, carbonaceous residue remains. Transfer the crucible and its contents to the muffle furnace, maintained at 950 C 25 C, and heat for about 1 h until all the carbon is completely
37、 oxidized and a clean ash is obtained. Remove the crucible and its contents from the furnace, allow to cool to ambient temperature in a desiccator and weigh to the nearest 0,1 mg. Then heat the crucible and its contents again for about 30 min in the muffle furnace, maintained at 950 C 25 C, allow to
38、 cool to ambient temperature in the desiccator and reweigh to the nearest 0,1 mg. If this mass differs from the previous mass by more than 1 % relative to the amount of ash, repeat the heating, cooling and weighing procedure until the difference between two successive weighings is less than 1 % rela
39、tive to the amount of ash. 8 Expression of results The ash content is given, as a percentage by mass, by the formula where m0is the mass, in grams, of the test portion; m1is the mass, in grams, of the empty crucible; m2is the mass, in grams, of the crucible and ash. m2 m1 m0 - -100 Licensed Copy: Lo
40、ndon South Bank University, London South Bank University, Fri Dec 08 14:33:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7164-5:1991 BSI 10-19993 9 Test report The test report shall include the following particulars: a) all details required for full identification of the piece or sample; b) a ref
41、erence to this International Standard; c) the method employed method A or method B; d) the temperature used and the reason for its choice if 950 C is used for method A; e) the ash content of the product tested, as a percentage by mass; f) the date of the test. Licensed Copy: London South Bank Univer
42、sity, London South Bank University, Fri Dec 08 14:33:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 blank Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 14:33:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7164-5:1991 BSI 10-1999 Publication(s) referred to S
43、ee national foreword. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 14:33:24 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7164-5: 1991 ISO 247:1990 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body
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