1、November 2014Translation by DIN-Sprachendienst.English price group 6No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS
2、 83.040.10!%4“2270217www.din.deDDIN ISO 125Natural rubber latex concentrate Determination of alkalinity (ISO 125:2011),English translation of DIN ISO 125:2014-11Naturkautschuk-Latex-Konzentrat Bestimmung der Alkalitt (ISO 125:2011),Englische bersetzung von DIN ISO 125:2014-11Latex concentr de caoutc
3、houc naturel Dtermination de lalcalinit (ISO 125:2011),Traduction anglaise de DIN ISO 125:2014-11SupersedesDIN ISO 125:2008-06www.beuth.deIn case of doubt, the German-language original shall be considered authoritative.Document comprises 9 pages10.14 A comma is used as the decimal marker. Contents P
4、age National foreword .3 National Annex NA (informative) Bibliography .4 1 Scope .5 2 Normative references .5 3 Principle .5 4 Reagents 5 5 Apparatus 6 6 Sampling 6 7 Procedure 6 7.1 General 6 7.2 Potentiometric titration 6 7.3 Titration using a visual indicator 6 8 Expression of results .6 9 Precis
5、ion 7 10 Test report .7 Annex A (informative) Precision statement .8 Bibliography 9 2DIN ISO 125:2014-11National foreword This document (ISO 125:2011) has been prepared by Technical Committee ISO/TC 45 “Rubber and rubber products”, Subcommittee SC 3 “Raw materials (including latex) for use in the ru
6、bber industry”. The responsible German body involved in its preparation was the DIN-Normenausschuss Materialprfung (DIN Standards Committee Materials Testing), Working Committee NA 062-04-35 AA Rohmaterialien (ein-schlielich Latex) fr die Kautschukindustrie. Attention is drawn to the possibility tha
7、t some of the elements of this document may be the subject of patent rights. DIN and/or DKE shall not be held responsible for identifying any or all such patent rights. The DIN Standards corresponding to the International Standards referred to in this document are as follows: ISO 123 DIN ISO 123 ISO
8、 976 DIN ISO 976 ISO 13773 DIN ISO 13773 Amendments This standard differs from DIN ISO 125:2008-06 as follows: a) in Clause 4, instructions for standardizing the HCI solution have been included; b) in Clause 7, more detailed instructions for the titration using a visual indicator have been included;
9、 c) the precision data have been moved to an informative annex. Previous editions DIN 53565: 1965-11, 1982-11 DIN ISO 125: 1993-09, 2008-06 3DIN ISO 125:2014-11National Annex NA (informative) Bibliography DIN ISO 123, Rubber latex Sampling DIN ISO 976, Rubber and plastics Polymer dispersions and rub
10、ber latices Determination of pH DIN ISO 13773, Rubber Polychloroprene latex Determination of alkalinity 4DIN ISO 125:2014-11WARNING 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 a
11、ny, 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 regulatory conditions.1 ScopeThis International Standard specifies a method for the determination of the alkalinity of natural rubber late
12、x concentrate.The method is not necessarily suitable for latices from natural sources other than Hevea brasiliensis or for synthetic rubber latices, compounded latex, vulcanized latex or artificial dispersions of rubber.NOTE A method for the determination of the alkalinity of polychloroprene latex i
13、s specified in ISO 13773 (see the Bibliography).2 Normative referencesThe 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
14、amendments) applies.ISO 123, Rubber latex SamplingISO 976, Rubber and plastics Polymer dispersions and rubber latices Determination of pH3 PrincipleA test portion of latex concentrate is titrated with acid to pH 6 in the presence of a stabilizer to prevent coagulation, either electrometrically or wi
15、th methyl red as a visual indicator. The alkalinity is calculated from the quantity of acid required.4 ReagentsDistilled water or water of equivalent purity shall be used wherever water is specified.4.1 Stabilizer solution: 5 % (by mass) solution of a non-ionic stabilizer of the alkyl phenol polyeth
16、ylene oxide condensate type. Before use, the pH of the solution shall be adjusted to a value of 6,0 0,05.The following reagents shall be of recognized analytical quality:4.2 Sulfuric acid, c(H2SO4) = 0,05 mol/dm3, or hydrochloric acid, c(HCl) = 0,1 mol/dm3, standard volumetric solution.Standardize t
17、he 0,1 mol/dm3HCl by pipetting 10 ml of 0,05 mol/dm3Na2CO3solution (4.4) into a flask and titrating with the 0,1 mol/dm3HCl, using methyl orange (4.5) as indicator.4.3 Methyl red, 0,1 % solution in ethanol of minimum purity 95 % (by volume).Natural rubber latex concentrate Determination of alkalinit
18、y 5DIN ISO 125:2014-114.4 Sodium carbonate solution, c(Na2CO3) = 0,05 mol/dm3.Dry the Na2CO3used to prepare this solution at 120 C 5 C for 2 h before preparing the solution.4.5 Methyl orange, 0,1 % solution in ethanol of minimum purity 95 % (by volume).5 ApparatusStandard laboratory equipment togeth
19、er with:5.1 Electric stirrer, with earthed (grounded) motor and non-metallic propeller-type blade, or magnetic stirrer.5.2 pHmeter, equipped with a combined electrode suitable for use in solutions up to pH 12, as specified in ISO 976, and capable of being read to 0,02 pH-units.5.3 Balance, capable o
20、f being read to 0,01 g.6 SamplingCarry out sampling in accordance with one of the methods specified in ISO 123.7 Procedure7.1 GeneralCarry out the determination in duplicate.To about 200 cm3of water in a 400 cm3beaker add, while stirring, 10 cm3of stabilizer solution (4.1).Weighing to the nearest 10
21、 mg, add by difference from a weighing bottle between 5 g and 10 g of the latex concentrate and stir until thoroughly mixed.Ensure that the latex is added so that none runs down the side of the beaker (which could result in loss of ammonia) or down the side of the weighing bottle.Titrate the resulti
22、ng mixture either by the method described in 7.2 or by that described in 7.3.7.2 Potentiometric titrationInsert the electrode of the pH-meter and, with continual stirring, add from a burette sulfuric acid or hydrochloric acid solution (4.2), adding the acid drop by drop on approaching the end point
23、of pH 6,0 0,05.7.3 Titration using a visual indicatorAdd 2 or 3 drops of methyl red (4.3) to the mixture and titrate with 0,1 mol/dm3HCl (see 4.2), taking as the end point the colour change from yellow to pink.8 Expression of results8.1 Depending on whether the latex concentrate has been preserved w
24、ith ammonia or potassium hydroxide, calculate the alkalinity as specified in 8.2 or 8.3, respectively.6DIN ISO 125:2014-118.2 If the latex concentrate is preserved with ammonia, calculate the alkalinity as the percentage (by mass) of ammonia (NH3) in the latex concentrate, as follows:Alkalinity (as
25、NH3) = F cVm1whereF1is a factor: 1,7 for hydrochloric acid or 3,4 for sulfuric acid;c is the actual concentration, expressed in moles of HCl or H2SO4per cubic decimetre of acid used;V is the volume, in cubic centimetres, of acid used;m is the mass, in grams, of the test portion.Report the result as
26、the mean of the duplicate determinations. If the individual results differ by more than 0,01 units from the mean where the actual alkalinity is above 0,5 units, or by more than 0,005 units from the mean where the actual alkalinity is 0,5 units or less, repeat the determination.8.3 If the latex is pr
27、eserved with potassium hydroxide, calculate the alkalinity as the percentage (by mass) of potassium hydroxide in the latex concentrate, as follows:Alkalinity (as KOH) = F cVm1whereF1is a factor: 5,61 for hydrochloric acid or 11,22 for sulfuric acid;c, V and m are as defined in 8.2.Report the result
28、as the mean of the duplicate determinations. If the individual results differ by more than 0,015 units from the mean, repeat the determination.9 PrecisionSee Annex A.10 Test reportThe test report shall include the following information:a) a reference to this International Standard;b) all details nec
29、essary to identify the test sample;c) the mean of the determinations, and the units in which it is expressed;d) full details of any incident likely to have affected the result;e) full details of any operation not included in this International Standard or in any of the International Standards to whi
30、ch reference is made, together with details of any operation regarded as optional;f) the date of the test.7DIN ISO 125:2014-11Annex A (informative) Precision statementA.1 The precision of this method has been determined in accordance with ISO/TR 9272. Refer to ISO/TR 9272 for terminology and other s
31、tatistical details.A.2 The precision data are given in Table A.1. The precision parameters shall not be used for acceptance or rejection of any group of materials without documentation stating that the parameters are applicable to those particular materials and specific test protocols that include t
32、hese test methods. The precision is expressed on the basis of a 95 % confidence level for the values established for repeatability r and reproducibility R.A.3 The results contained in Table A.1 are average values and give an estimate of the precision of this test method as determined in an interlabo
33、ratory test programme carried out in 2001 and including 13 laboratories performing triplicate analyses on two samples A and B which were prepared from high-ammonia latex. Before the bulk was subsampled into 1 l bottles labelled A and B, it was filtered and homogenized by thorough stirring. Thus, ess
34、entially, 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 given to them.A.4 A Type 1 precision was evaluated based on the method of preparation of the latex
35、 samples used for the interlaboratory test programme.A.5 Repeatability: The repeatability r (in measurement units) of the test method has been established as the appropriate value tabulated in Table A.1. Two single test results, obtained in the same laboratory under normal test method procedures, th
36、at differ by more than the tabulated r (for any given level) shall be considered to have come from different, or non-identical, sample populations.A.6 Reproducibility: The reproducibility R (in measurement units) of the test method has been established as the appropriate value tabulated in Table A.1
37、. Two single test results, obtained in different laboratories under normal test method procedures, that differ by more than the tabulated R (for any given level) shall be considered to have come from different, or non-identical, sample populations.A.7 Bias: In test method terminology, bias is the di
38、fference 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 cannot therefore be determined for this particular method.Table A.1 Precisi
39、on dataAverage resultsWithinlaboratory Between laboratoriessrr sRR0,64 0,007 0,02 0,013 0,04r = 2,83 srwhere r is the repeatability (in measurement units) and sris the within-laboratory standard deviation.R = 2,83 sRwhere R is the reproducibility (in measurement units) and sRis the between-laboratory standard deviation.8DIN ISO 125:2014-11Bibliography1 ISO/TR 9272, Rubber and rubber products Determination of precision for test method standards2 ISO 13773, Rubber Polychloroprene latex Determination of alkalinity9DIN ISO 125:2014-11
