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1、 Reference number ISO 126:2005(E) ISO 2005 INTERNATIONAL STANDARD ISO 126 Fifth edition 2005-04-01 Natural rubber latex concentrate Determination of dry rubber content Latex de caoutchouc naturel concentr Dtermination de la teneur en caoutchouc sec Copyright International Organization for Standardiz
2、ation Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 19:21:04 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 126:2005(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Ad
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5、re has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ISO 2005 All rights reserved. Unless otherwise specified, no part of this publication ma
6、y be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel.
7、 + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2005 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/
8、24/2007 19:21:04 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 126:2005(E) ISO 2005 All rights reserved iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of prepar
9、ing 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 committee. International organizations, governmental and non-governmental, in li
10、aison 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 accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of
11、 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 requires approval by at least 75 % of the member bodies casting a vote. Attention is
12、 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 126 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 3, Raw materia
13、ls (including latex) for use in the rubber industry. This fifth edition cancels and replaces the fourth edition (ISO 126:1995), which has been technically revised and a statement of the precision of the method added. Copyright International Organization for Standardization Provided by IHS under lice
14、nse with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 19:21:04 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards
15、1/9972545001 Not for Resale, 04/24/2007 19:21:04 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 126:2005(E) ISO 2005 All rights reserved 1 Natural rubber latex concentrate Determination of dry rubber content WARNING Persons using this Internation
16、al 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 any national
17、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 than Hevea bras
18、iliensis, 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 edition cited
19、 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 standards 3 T
20、erms 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 portion of latex
21、 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. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/
22、9972545001 Not for Resale, 04/24/2007 19:21:04 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 126:2005(E) 2 ISO 2005 All rights reserved 5 Reagents During the analysis, use only reagents of recognized analytical quality and only distilled water or water of equivalent p
23、urity. 5.1 Acetic acid, 20 g/dm3 aqueous solution, for use with latex concentrate preserved 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.
24、For use with latex concentrate preserved with potassium hydroxide. 5.3 Ethanol, 95 % (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 unsuitab
25、le for use with latex concentrate containing potassium hydroxide. 6.2 Balance, capable 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
26、 8.1 If the total solids is not known, determine it in accordance with ISO 124. 8.2 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
27、edge of the dish to reduce the solids content of the latex concentrate to (20 1) % (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 a
28、mmonia or potassium hydroxide, respectively. 8.4 In the case of latex concentrate preserved 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 d
29、epress 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. 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
30、with potassium hydroxide, add 25 cm3 5 cm3 of 50 g/dm3 acetic acid solution (5.2). Mix 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.
31、Cover the dish with a watch glass and heat on a steam bath for 15 min to 30 min. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 19:21:04 MDTNo reproduction or networking permitt
32、ed without license from IHS -,-,- ISO 126:2005(E) ISO 2005 All rights reserved 3 8.6 When the serum is clear, collect any small particles of coagulated rubber by rubbing with the main bulk. Soak the coagulated rubber in several changes of water until the water is no longer acidic to litmus. Press th
33、e 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 with a glass stopper about 45 mm in diameter, or a small photographic roller, to press first around the circumference an
34、d 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 latex concentrate preserved with potassium hydroxide. Allow the rinsed sheet to drip for a few minutes before transfe
35、rring 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 three times during the first few hours of drying. Allow to cool in a desiccator for 30 min and weigh. Repeat the oper
36、ation 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 oxidation is taking place at 70 C, then use a lower drying temperature, for example 55 C. 9 Expression of results 9.1
37、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, of the test portion; m1 is the mass, in grams, of the dry sheet. 9.2 The results of the duplicate determinations sha
38、ll 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 determined in accordance with ISO/TR 9272. Please refer to this document for terminology and explanations of statistical
39、 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 parameters are applicable to the particular group of materials and the specific test protocols of this test method. T
40、he 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 average values and give an estimate of the precision of this test method as determined in an inter-laboratory test program
41、me (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 into 1-litre bottles labelled A and B, it was filtered and homogenized by thorough blending and stirring. Thus, essent
42、ially, 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 samples on the dates which had been given to the participants in the ITP. 10.3 A Type 1 precision was determined (the test s
43、amples used for the ITP were distributed in the prepared state, ready for testing). Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/24/2007 19:21:04 MDTNo reproduction or networking perm
44、itted without license from IHS -,-,- ISO 126:2005(E) 4 ISO 2005 All rights reserved 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 no
45、rmal test conditions, that differ by more than the tabulated value of r (for any given level) shall be considered to have come from different (non-identical) sample populations. 10.5 Reproducibility: The reproducibility R (in measurement units) of this test method has been established as the appropr
46、iate value tabulated in Table 1. Two single test results, obtained in two different laboratories 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 different (non-identical) sample populations. 10.6 Bias: In tes
47、t method terminology, bias is the difference between an average test value and the reference (or true) test property value. Reference values do not exist for this test method since the value (of the test property) is exclusively defined by the test method. Bias, therefore, cannot be determined for t
48、his particular test method. Table 1 Estimate of precision for DRC test method Within lab Between labs Average sr r sR R 60,26 0,029 0,06 0,046 0,13 r = 2,83 sr where r is the repeatability (in measurement units) and sr is the within-laboratory standard deviation. R = 2,83 sR where R is the reproducibility (in measurement units) and sR is the between-laboratory standard deviation. 11 Test report The test report shall include the following particulars: a) a reference to this International Standard; b) all details necessary for the identificati