1、June 2008DEUTSCHE NORM English price group 7No part of this standard 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 83.040.10!$O?“1442528www.d
2、in.deDDIN ISO 35Natural rubber latex concentrate Determination of mechanical stability (ISO 35:2004 + Amd. 1:2006)English version of DIN ISO 35:2008-06Naturkautschuk-Latex-Konzentrat Bestimmung der mechanischen Stabilitt (ISO 35:2004 + Amd. 1:2006)Englische Fassung DIN ISO 35:2008-06SupersedesDIN IS
3、O 35:1997-04www.beuth.deDocument comprises 8 pagesDIN ISO 35:2008-06 Contents Page National foreword .3 National Annex NA (informative) Bibliography 3 1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Principle5 5 Reagents.5 6 Apparatus .5 7 Sampling.6 8 Procedure .6 9 Expression of re
4、sults 7 10 Precision statement.7 11 Test report 8 2 DIN ISO 35:2008-06 National foreword This standard has been prepared by Technical Committee ISO/TC 45 “Rubber and rubber products”, Subcommittee SC 3 “Raw materials (including latex) for use in the rubber industry”. The responsible German body invo
5、lved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Technical Committee NA 062-04-32 AA Prfung von Latex. The DIN Standards corresponding to the International Standards referred to in this document are as follows: ISO 123 DIN ISO 123 ISO 125 DIN IS
6、O 125 ISO 3310-1 DIN ISO 3310-1 Amendments This standard differs from DIN ISO 35:1997-04 as follows: a) Reference to ISO/TR 9272 has been added to Clause 2 “Normative references”. b) Clause 10 “Precision statement” has been added. c) ISO 35:2004 and Amendment 1:2006 have been adopted in full. Previo
7、us editions DIN 53565: 1967-12, 1983-01 DIN ISO 35: 1997-04 National Annex NA (informative) Bibliography DIN ISO 123, Rubber latex Sampling DIN ISO 125, Natural rubber latex concentrate Determination of alkalinity DIN ISO 3310-1, Test sieves Technical requirements and testing Part 1: Test sieves of
8、metal wire cloth 3 DIN ISO 35:2008-06 Natural rubber latex concentrate Determination of mechanical stability 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
9、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 Scope This International Standard specifies a method for the determination of the mechanical stability of natural rubber latex c
10、oncentrate. It is also applicable to prevulcanized natural rubber latex concentrate. The method is not necessarily suitable for latices or prevulcanized latex preserved with potassium hydroxide, latices from natural sources other than Hevea brasiliensis, or for compounded latex or artificial dispers
11、ions 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 applies. For undated references, the latest edition of the referenced d
12、ocument (including any amendments) applies. ISO 123, Rubber latex Sampling ISO 124, Latex, rubber Determination of total solids content ISO 125, Natural rubber latex concentrate Determination of alkalinity ISO 3310-1, Test sieves Technical requirements and testing Part 1: Test sieves of metal wire c
13、loth ISO/TR 9272, Rubber and rubber 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 preservati
14、ves, with the exception of potassium hydroxide, and which has been subjected to some process of concentration 3.2 mechanical stability time, in seconds, required to initiate visible flocculation under the specified test conditions 4 4PrincipleA test portion of the latex concentrate is diluted to by
15、mass total solids content and stirred at high speed.The time required to initiate visible flocculation is recorded, this being regarded as a measure of the mechanicalstability.5ReagentsThe ammonia solutions (5.1 and 5.2) shall be prepared from ammonium hydroxide of recognized analyticalreagent quali
16、ty and shall be stored in closed containers.Carbonate-free distilled water or water of equivalent purity shall be used for dilution of the latex. Deionized watermay be used for the detection of the end-point.5.1 Ammonia solution containing by mass of ammonia (NH3), for use with latex concentrate hav
17、ingan alkalinity of at least (with respect to the latex concentrate).5.2 Ammonia solution containing by mass of ammonia (NH3), for use with latex concentrate havingan alkalinity of less than (with respect to the latex concentrate).6 ApparatusStandard laboratory apparatus, plus the following:6.1 Mech
18、anical stability measuring apparatus,1)consisting of the items described in 6.1.1 to 6.1.3.6.1.1 Latex container: A flat-bottomed, cylindrical container at least high, with an internal diameter ofand a wall thickness of approximately . The inner surface shall be smooth.A poly(methyl methylacrylate)
19、or glass container is suitable.6.1.2 Stirring apparatus, consisting of a vertical stainless-steel shaft of sufficient length to reach the bottomof the latex container (6.1.1) and tapering to approximately in diameter at its lower end, where anexactly centred, horizontal, smooth, stainless-steel disc
20、, in diameter andthick, is attached. The apparatus shall be capable of maintaining a stirring rate ofthroughout a test, at which frequency the shaft shall not run out of true by morethan .6.1.3 Holder, for the latex container (6.1.1). The holding arrangement shall ensure that the latex container ish
21、eld securely, that the axis of the rotating shaft is concentric with that of the container and that the bottom of thestirring disc is from the inner surface of the bottom of the latex container.6.2 Large Petri dish, with a diameter not less than and depth not less than . The size of thePetri dish wi
22、ll permit several tests to be carried out in the same dish.6.3 Pointed rods: Thin rods, of glass or an inert material such as stainless steel, which have been drawn outor machined to a point. The precise dimensions are not important since the function of the rod is to pick up asmall droplet of latex
23、.1) Suitable instruments are available commercially, e.g. from Klaxon Signals Ltd., Honey Pot Lane, Stanmore, HA7 1BE,U.K., Telefax +44 (208) 952 6983. This information is given for the convenience of users of this International Standard anddoes not constitute an endorsement by ISO of this product.5
24、5 %1,6 %0,30 %0,6 %0,30 %90 mm58 mm 1 mm 2,5 mm6,3 mm20,83 mm 0,03 mm1,57 mm 0,05 mm14 000 rev/min 200 rev/min0,25 mm13 mm 1mm150 mm 20 mmDIN ISO 35:2008-06 5 6.4 Means of heating: Use either a water bath, capable of maintaining a temperature of ;or a glass tube, bent to a shape suitable for inserti
25、on in the latex concentrate. together with a means ofcirculating water at a temperature of through the tube.6.5 Wire cloth, of stainless steel, complying with the requirements of ISO 3310-1, with an average aperturewidth of .7 SamplingCarry out sampling in accordance with one of the methods specifie
26、d in ISO 123.NOTE Mechanical stability may be adversely affected by the duration and temperature of storage of the sample.8 Procedure8.1 GeneralCarry out the determination in duplicate within of first opening the sample bottle. If the total solids contentand alkalinity of the latex concentrate are n
27、ot known, determine them in accordance with ISO 124 and ISO 125,respectively.NOTE If the concentration of the carbon dioxide in the atmosphere in the vicinity of the mechanical stability measuringapparatus (6.1) is above normal (about by volume), the mechanical stability of the latex will be reduced
28、. This effectmay be pronounced at carbon dioxide concentrations as low as by volume. High concentrations of carbon dioxide inthe atmosphere may be caused by the proximity of any apparatus which generates carbon dioxide, such as certain types ofgas or oil heater.8.2 Dilution and stirringDilute of lat
29、ex concentrate, in a glass beaker, to by mass with the appropriate ammoniasolution (5.1 or 5.2). Without delay, warm the diluted latex with gentle stirring to to (i.e. slightlyabove the intended test temperature) by one of the means of heating (6.4). Immediately filter the diluted andwarmed latex th
30、rough the wire cloth (6.5) and weigh of the filtered latex into the container (6.1.1).Check the temperature of the latex is . Place the container in the holder (6.1.3) and stir the latex,ensuring that the rotational frequency of the stirrer is throughout the test, until theend-point is passed.8.3 De
31、termination of end-pointThe arrival of the end-point is preceded by a marked decrease in the depth of the vortex around the stirringshaft, accompanied by loss of turbulence and a change in the sound of the stirring action.Two methods are permitted for the determination of the end-point. Inexperience
32、d operators should have themethod of determining the end-point demonstrated to them.a) Palm-of-the-hand method: Determine the end-point by removing a drop of the latex with a clean glass rodat intervals of and gently spreading the sample on the palm of the hand. Take the end-point as the firstappear
33、ance of flocculum. Confirm the end-point by the presence of an increased amount of flocculum in asample taken after stirring the latex for an additional .70C 10C70C 10C180 m 7,6 m24 h0,03 %0,05 %100 g 55,0 % 0,2 %35C37C80,0 g 0,5 g35C 1C14 000 rev/min 200 rev/min15 s15 sDIN ISO 35:2008-06 6 DIN ISO
34、35:2008-06 b) Dispersibility-in-water method: Take a large Petri dish (6.2) and introduce 100 cm3to 150 cm3of water. It will facilitate observation of the end-point if the Petri dish is standing on a dark surface such as black paper. Using a pointed rod (6.3), pick up a small drop of latex and immed
35、iately touch the surface of the water with it. If the latex has not started to flocculate, it will disperse within a few seconds to give a milky cloud. If flocculation has commenced, the droplet will generally remain on the surface of the water without dispersing. If it should start to disperse, the
36、n particles of flocculum will be readily apparent to the naked eye. 9 Expression of results Express the mechanical stability time of the latex concentrate as the number of seconds between the start of stirring and the end-point. Calculate the mean of the two determinations. If the results of the dup
37、licate determinations do not agree to within 5 % of their mean value, the test shall be repeated. 10 Precision statement 10.1 The precision of this method was determined in accordance with ISO/TR 9272. Refer to this document for terminology and explanations of statistical concepts. 10.2 The precisio
38、n details in this precision statement give an estimate of the precision of this test method with the materials used in the particular interlaboratory programme as described below. The precision parameters should not be used for acceptance/rejection testing of any group of materials without documenta
39、tion that the parameters are applicable to those particular materials and the specific test protocol of this test method. 10.3 The precision results are given in Table 1. The precision is expressed on the basis of a 95 % confidence level for the values established for repeatability r and reproducibi
40、lity R. 10.4 The results contained in Table 1 are mean values and give an estimate of the precision of this test method as determined in an interlaboratory test programme (ITP) conducted in 2001. Thirteen laboratories performed triplicate analyses, using the dispersibility-in-water method of end-poi
41、nt determination see 8.3 b), on two samples, A and B, which were prepared from highly ammoniated latex. The bulk latex was strained and then homogenized by thorough blending and stirring prior to being sub-sampled into 1-litre bottles labelled A and B. Thus, essentially, samples A and B were the sam
42、e 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. 10.5 A type 1 precision was determined, based on the sampling method used for the lat
43、ex samples in the ITP. 10.6 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
44、value of r (for any given level) shall be considered to have come from different (non-identical) sample populations. 10.7 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 results, obt
45、ained 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. 10.8 Bias: In test method terminology, bias is the difference between an average test value and the referenc
46、e (or true) test property value. 7 DIN ISO 35:2008-06 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 precision of determina
47、tion of mechanical stability time Mean Within laboratory Between laboratories s srr sRR 1 023 15 43 94 265 r = 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 b
48、etween-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 identification of the test sample; c) the method used for determining the end point 8.3 a) or 8.3 b); d) the m
49、ean mechanical stability time of the latex concentrate, quoted to the nearest 15 s; e) any unusual features noted during the determination; f) details of any operation not included in this International Standard or in the International Standards to which reference is made, as well as details of any procedure regarded as optional; g) the date of the test. 8
