BS ISO 126-2005 Natural rubber latex concentrate - Determination of dry rubber content《天然胶乳浓缩物 干橡胶含量的测定》.pdf

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1、BRITISH STANDARD BS ISO 126:2005 Natural rubber latex concentrate Determination of dry rubber content ICS 83.040.10 BS ISO 126:2005 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 21 April 2005 BSI 21 April 2005 ISBN 0 580 45891 1 National fo

2、reword 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 It supersedes BS 6057-3.4:1996 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee PRI/50, Rubber raw, natural and synthetic, including latex and

3、carbon black, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the

4、 section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct applicati

5、on. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monito

6、r related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, 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

7、in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments Reference number ISO 126:2005(E) OSI 5002INTERNATIONAL STANDARD ISO 126 Fifth edition 2005-04-01 Natural rubber latex concentrate Determination of dry rubber content Latex de caou

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13、 Allr ithgsr esedevrBSISO126:2005IS:621 O5002(E) I SO 5002 All irthgs ersedevr iiiForeword 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 throug

14、h 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 liaison with ISO, also take part in the work. ISO collaborat

15、es 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 technical committees is to prepare International Standard

16、s. 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 drawn to the possibility that some of the elements of thi

17、s 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 materials (including latex) for use in the rubber industry. This

18、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. BSISO126:2005blank 5002:621OSISBINTENRATIONAL TSANDADR IS:621 O5002(E)I SO 5002 All irthgs ersedevr 1Natural rubber latex concentrate Determi

19、nation of dry rubber content WARNING Persons 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 safe

20、ty and health practices and to ensure compliance with 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 pota

21、ssium hydroxide, latices from natural sources other than 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 applica

22、tion of this document. For dated references, only the 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 rubbe

23、r products Determination of precision for test method 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 t

24、o some process of concentration 4 Principle A test portion 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. BSISO126:2005IS:621 O5002(E) 2 I SO 5002 All irthgs ersedevr5 Rea

25、gents 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/dm 3aqueous solution, for use with latex concentrate preserved with ammonia. 5.2 Acetic acid, 50 g/dm 3solution in aqueous propan-2-ol, prepared

26、 by adding 50 g of glacial acetic acid to 500 cm 3of propan-2-ol and then diluting the resultant solution to 1 dm 3with water. 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, pre

27、ferably 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, capable of weighing to an accuracy of 1 mg. 6.3 Circulating-air oven, capable of maintaining a

28、 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 Carry out the procedure in duplicate. 8.3 Weigh by difference from a conical flask fitted

29、 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) % (by mass). Carefully rotate the dish on a smooth surface to dilute the latex and ensure ho

30、mogeneity. 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 preserved with ammonia, add, over a period of 5 min, 35 cm 3 5 cm 3of 20 g/dm 3acetic acid

31、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 with a watch glass and heat on a steam bath for 15 min to 30 min. If the serum remains m

32、ilky, add 5 cm 3of 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 cm 3 5 cm 3of 50 g/dm 3acetic acid solution (5.2). Mix the acidified latex by means of a thin glass rod and wash any latex concentrate rema

33、ining 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. BSISO126:2005IS:621 O5002(E) I SO 5002 All irthgs ersedevr 38.6 When the serum is clear, c

34、ollect 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 the coagulated rubber to expel water and obtain a uniform sheet not exceeding 2 mm in thickness. A convenient met

35、hod 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 and then work towards the centre. Rinse the sheet thoroughly in running water for at least 5 min in the case of l

36、atex 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 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

37、. 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 operation of drying, cooling and weighing until the loss in mass is less than 1 mg after heating for 30 min. If the

38、 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 Calculate the dry rubber content (DRC) of the latex concentrate as a percentage by mass to the second decimal p

39、lace from the equation: 1 0 DRC 100 m m = where m 0is the mass, in grams, of the test portion; m 1is 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 mea

40、n 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 concepts. The precision results are given in Table 1. The precision parameters shall not be used for acceptan

41、ce 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. The precision is expressed on the basis of a 95 % confidence level for the values established for repeatability

42、 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 programme (ITP) conducted in 2001. Thirteen laboratories performed triplicate analyses on two samples, A and B, which

43、 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, essentially, samples A and B were the same and were treated as such in the statistical computations. Each participat

44、ing 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 samples used for the ITP were distributed in the prepared state, ready for testing). BSISO126:2005IS:621 O5002(

45、E) 4 I SO 5002 All irthgs ersedevr10.4 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

46、 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 appropriate value tabulated in Table 1. Two single test r

47、esults, 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 test method terminology, bias is the difference betwe

48、en 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 this particular test method. Table 1 Estimate of pr

49、ecision for DRC test method Within lab Between labs Average s rr s RR 60,26 0,029 0,06 0,046 0,13 r = 2,83 s rwhere r is the repeatability (in measurement units) and s ris the within-laboratory standard deviation. R = 2,83 s Rwhere R is the reproducibility (in measurement units) and s Ris the between-laboratory standard deviation. 11 Test report The test report shall include the following particulars: a) a reference to this Intern