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1、BRITISH STANDARD BS ISO 126:2005 Natural rubber latex concentrate Determination of dry rubber content ICS 83.040.10 ? Licensed Copy: London South Bank University, London South Bank University, Thu Mar 01 09:15:50 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 126:2005 This British Standard was pu
2、blished under the authority of the Standards Policy and Strategy Committee on 21 April 2005 BSI 21 April 2005 ISBN 0 580 45891 1 National foreword This British Standard reproduces verbatim ISO 126:2005 and implements it as the UK national standard. It supersedes BS 6057-3.4:1996 which is withdrawn.
3、The UK participation in its preparation was entrusted to Technical Committee PRI/50, Rubber raw, natural and synthetic, including latex and carbon black, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-referenc
4、es The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Onli
5、ne. 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 does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsib
6、le international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover,
7、the ISO title page, pages ii and iii, a blank page, pages 1 to 4, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank Univers
8、ity, London South Bank University, Thu Mar 01 09:15:50 GMT+00:00 2007, Uncontrolled Copy, (c) BSI Reference number ISO 126:2005(E) OSI 5002 INTERNATIONAL STANDARD ISO 126 Fifth edition 2005-04-01 Natural rubber latex concentrate Determination of dry rubber content Latex de caoutchouc naturel concent
9、r Dtermination de la teneur en caoutchouc sec BS ISO 126:2005 Licensed Copy: London South Bank University, London South Bank University, Thu Mar 01 09:15:50 GMT+00:00 2007, Uncontrolled Copy, (c) BSI IS:621 O5002(E) DPlcsid Fremia ihTs PDF file may ctnoian emdebt dedyfepcaes. In ccaocnadrw eith Aebo
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14、4 + 10 947 22 1 11 xaF0 947 22 14 + 9 74 E-mail coirypthgiso.o gr We bwww.is.o gro Pulbisdehi n Switlrez dna ii ISO 5002 Allr ithgsr esedevr BS ISO 126:2005 Licensed Copy: London South Bank University, London South Bank University, Thu Mar 01 09:15:50 GMT+00:00 2007, Uncontrolled Copy, (c) BSI IS:62
15、1 O5002(E) I SO 5002 All irthgs ersedevr iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each memb
16、er body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Ele
17、ctrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance 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 adop
18、ted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires 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 pate
19、nt rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 126 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 3, Raw materials (including latex) for use in the rubber industry. This fifth edition cancels and replaces th
20、e fourth edition (ISO 126:1995), which has been technically revised and a statement of the precision of the method added. BS ISO 126:2005 Licensed Copy: London South Bank University, London South Bank University, Thu Mar 01 09:15:50 GMT+00:00 2007, Uncontrolled Copy, (c) BSI blank 5002:621 OSI SB Li
21、censed Copy: London South Bank University, London South Bank University, Thu Mar 01 09:15:50 GMT+00:00 2007, Uncontrolled Copy, (c) BSI INTENRATIONAL TSANDADR IS:621 O5002(E) I SO 5002 All irthgs ersedevr 1 Natural rubber latex concentrate Determination of dry rubber content WARNING Persons using th
22、is 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 compliance with
23、 any national regulatory conditions. 1 Scope This International Standard specifies a method for the determination of the dry rubber content of natural rubber latex concentrate. The method is not necessarily suitable for latices preserved with potassium hydroxide, latices from natural sources other t
24、han Hevea brasiliensis, or for compounded latex, vulcanized latex or artificial dispersions of rubber and it is not applicable to synthetic rubber latices. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the
25、 edition cited applies. For undated references, the latest edition of the referenced document (including amendments) applies. ISO 123, Rubber latex Sampling ISO 124, Latex, rubber Determination of total solids content ISO/TR 9272, Rubber and rubber products Determination of precision for test method
26、 standards 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 natural rubber latex concentrate natural rubber latex containing ammonia and/or other preservatives and which has been subjected to some process of concentration 4 Principle A test po
27、rtion of latex concentrate is diluted to 20 % (by mass) total solids content and acidified with acetic acid. The coagulated rubber is then formed into a sheet and dried at 70 C 5 C. BS ISO 126:2005 Licensed Copy: London South Bank University, London South Bank University, Thu Mar 01 09:15:50 GMT+00:
28、00 2007, Uncontrolled Copy, (c) BSI IS:621 O5002(E) 2 I SO 5002 All irthgs ersedevr 5 Reagents During the analysis, use only reagents of recognized analytical quality and only distilled water or water of equivalent purity. 5.1 Acetic acid, 20 g/dm3 aqueous solution, for use with latex concentrate pr
29、eserved with ammonia. 5.2 Acetic acid, 50 g/dm3 solution in aqueous propan-2-ol, prepared by adding 50 g of glacial acetic acid to 500 cm3 of propan-2-ol and then diluting the resultant solution to 1 dm3 with water. For use with latex concentrate preserved with potassium hydroxide. 5.3 Ethanol, 95 %
30、 (by volume). 6 Apparatus Standard laboratory apparatus plus the following: 6.1 Dish, preferably made of glass or porcelain, approximately 100 mm in diameter and 50 mm deep. NOTE Dishes made of aluminium are unsuitable for use with latex concentrate containing potassium hydroxide. 6.2 Balance, capab
31、le of weighing to an accuracy of 1 mg. 6.3 Circulating-air oven, capable of maintaining a temperature of 70 C 5 C. 7 Sampling Carry out sampling in accordance with one of the methods specified in ISO 123. 8 Procedure 8.1 If the total solids is not known, determine it in accordance with ISO 124. 8.2
32、Carry out the procedure in duplicate. 8.3 Weigh by difference from a conical flask fitted with a stopper, to the nearest 1 mg, 10 g 1 g of latex concentrate into the dish (6.1). Pour sufficient water down the inside edge of the dish to reduce the solids content of the latex concentrate to (20 1) % (
33、by mass). Carefully rotate the dish on a smooth surface to dilute the latex and ensure homogeneity. Proceed in accordance with 8.4 or 8.5 as appropriate, depending on whether the latex concentrate is preserved with ammonia or potassium hydroxide, respectively. 8.4 In the case of latex concentrate pr
34、eserved with ammonia, add, over a period of 5 min, 35 cm3 5 cm3 of 20 g/dm3 acetic acid solution (5.1), pouring it down the inside edge of the dish and slowly rotating the dish while the acid is being added. Gently depress the coagulated sheet of rubber below the surface of the acid. Cover the dish
35、with a watch glass and heat on a steam bath for 15 min to 30 min. If the serum remains milky, add 5 cm3 of 95 % (by volume) ethanol (5.3). Continue as described in 8.6. 8.5 In the case of latex concentrate preserved with potassium hydroxide, add 25 cm3 5 cm3 of 50 g/dm3 acetic acid solution (5.2). M
36、ix the acidified latex by means of a thin glass rod and wash any latex concentrate remaining on the rod into the dish with a little water. Gently depress the coagulated sheet of rubber below the surface of the acid. Cover the dish with a watch glass and heat on a steam bath for 15 min to 30 min. BS
37、ISO 126:2005 Licensed Copy: London South Bank University, London South Bank University, Thu Mar 01 09:15:50 GMT+00:00 2007, Uncontrolled Copy, (c) BSI IS:621 O5002(E) I SO 5002 All irthgs ersedevr 3 8.6 When the serum is clear, collect any small particles of coagulated rubber by rubbing with the mai
38、n bulk. Soak the coagulated rubber in several changes of water until the water is no longer acidic to litmus. Press the coagulated rubber to expel water and obtain a uniform sheet not exceeding 2 mm in thickness. A convenient method is to place the coagulated rubber carefully on a glass plate and wi
39、th a glass stopper about 45 mm in diameter, or a small photographic roller, to press first around the circumference and then work towards the centre. Rinse the sheet thoroughly in running water for at least 5 min in the case of latex concentrate preserved with ammonia, or at least 2 h in the case of
40、 latex concentrate preserved with potassium hydroxide. Allow the rinsed sheet to drip for a few minutes before transferring it to the drying oven (6.3). 8.7 Dry the sheet at a temperature of 70 C 5 C until it has no white patches. If the sheet is dried on a watch glass, carefully turn it over two or
41、 three times during the first few hours of drying. Allow to cool in a desiccator for 30 min and weigh. Repeat the operation of drying, cooling and weighing until the loss in mass is less than 1 mg after heating for 30 min. If the sheet becomes excessively sticky and it is suspected that significant
42、oxidation is taking place at 70 C, then use a lower drying temperature, for example 55 C. 9 Expression of results 9.1 Calculate the dry rubber content (DRC) of the latex concentrate as a percentage by mass to the second decimal place from the equation: 1 0 DRC100 m m = where m0 is the mass, in grams
43、, of the test portion; m1 is the mass, in grams, of the dry sheet. 9.2 The results of the duplicate determinations shall agree to within 0,1 % (by mass) of the mean value. If they do not, repeat the determination. Report the mean value. 10 Precision statement 10.1 The precision of this method was de
44、termined in accordance with ISO/TR 9272. Please refer to this document for terminology and explanations of statistical concepts. The precision results are given in Table 1. The precision parameters shall not be used for acceptance or rejection of any group of materials without documentation that the
45、 parameters are applicable to the particular group of materials and the specific test protocols of this test method. The precision is expressed on the basis of a 95 % confidence level for the values established for repeatability r and reproducibility R. 10.2 The results contained in Table 1 are aver
46、age values and give an estimate of the precision of this test method as determined in an inter-laboratory test programme (ITP) conducted in 2001. Thirteen laboratories performed triplicate analyses on two samples, A and B, which were prepared from high-ammonia latex. Before the bulk was sub-sampled
47、into 1-litre bottles labelled A and B, it was filtered and homogenized by thorough blending and stirring. Thus, essentially, samples A and B were the same and were treated as such in the statistical computations. Each participating laboratory was required to carry out the test using these two sample
48、s on the dates which had been given to the participants in the ITP. 10.3 A Type 1 precision was determined (the test samples used for the ITP were distributed in the prepared state, ready for testing). BS ISO 126:2005 Licensed Copy: London South Bank University, London South Bank University, Thu Mar
49、 01 09:15:50 GMT+00:00 2007, Uncontrolled Copy, (c) BSI IS:621 O5002(E) 4 I SO 5002 All irthgs ersedevr 10.4 Repeatability: The repeatability r (in measurement units) of this test method has been established as the appropriate value tabulated in Table 1. Two single test results, obtained in the same laboratory under normal test conditions, that differ by more than the tabulated value of r (for any given level) shall be considered to have come from dif