1、BSI Standards PublicationBS ISO 34-2:2015Rubber, vulcanized orthermoplastic Determinationof tear strengthPart 2: Small (Delft) test piecesBS ISO 34-2:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 34-2:2015. It supersedes BS ISO 34-2:2011 which is withdra
2、wn.The UK participation in its preparation was entrusted to Technical Committee PRI/22, Physical testing of rubber.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract
3、. Users are responsible for its correct application. The British Standards Institution 2015.Published by BSI Standards Limited 2015ISBN 978 0 580 87264 8ICS 83.060Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority
4、of the Standards Policy and Strategy Committee on 30 June 2015.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 34-2:2015 ISO 2015Rubber, vulcanized or thermoplastic Determination of tear strength Part 2: Small (Delft) test piecesCaoutchouc vulcanis ou thermoplastique
5、 Dtermination de la rsistance au dchirement Partie 2: Petites prouvettes (prouvettes de Delft)INTERNATIONAL STANDARDISO34-2Fourth edition2015-06-01Reference numberISO 34-2:2015(E)BS ISO 34-2:2015ISO 34-2:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015, Published in Switze
6、rlandAll rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requ
7、ested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 34-2:2015ISO 34-2:2015(E)Foreword iv1 Scope . 12
8、 Normative references 13 Principle 14 Apparatus . 15 Calibration 26 Test pieces . 26.1 Shape and dimensions 26.2 Measurement of dimensions . 26.2.1 Measurement of thickness. 26.2.2 Measurement of the total width outside the slit 46.3 Time interval between vulcanization and testing 66.4 Number 67 Tem
9、perature of test . 68 Procedure. 69 Expression of results 610 Precision . 611 Test report . 7Annex A (informative) Precision results from an interlaboratory test programme . 8Annex B (normative) Calibration schedule 11Bibliography .12 ISO 2015 All rights reserved iiiContents PageBS ISO 34-2:2015ISO
10、34-2:2015(E)ForewordISO (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 member body interested in a subject fo
11、r 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 Electrotechnical Commission (IEC) on
12、all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted.
13、This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is 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
14、 or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of us
15、ers and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplement
16、ary informationThe committee responsible for this document is ISO/TC 45, Rubber and rubber products, Subcommittee SC 2, Testing and analysis.This fourth edition cancels and replaces the third edition (ISO 34-2:2011), which has been technically revised. Precision results from an interlaboratory have
17、been updated as Annex A.ISO 34 consists of the following parts, under the general title Rubber, vulcanized or thermoplastic Determination of tear strength: Part 1: Trouser, angle and crescent test pieces Part 2: Small (Delft) test piecesiv ISO 2015 All rights reservedBS ISO 34-2:2015Rubber, vulcaniz
18、ed or thermoplastic Determination of tear strength Part 2: Small (Delft) test piecesWARNING 1 Persons using this part of ISO 34 should be familiar with normal laboratory practice. This part of ISO 34 does not purport to address all of the safety problems, if any, associated with its use. It is the r
19、esponsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.WARNING 2 Certain procedures specified in this part of ISO 34 might involve the use or generation of substances, or the generation of waste, that could cons
20、titute a local environmental hazard. Reference should be made to appropriate documentation on safe handling and disposal after use.1 ScopeThis part of ISO 34 specifies a method for the determination of the tear strength of small test pieces (Delft test pieces) of vulcanized or thermoplastic rubber.N
21、OTE The method does not necessarily give results agreeing with those given by the method described in ISO 34-1, which uses trouser, angle and crescent test pieces. It is used in preference to ISO 34-1 when the amount of material available is limited, and might be particularly suitable for testing sm
22、all finished products.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document
23、 (including any amendments) applies.ISO 5893, Rubber and plastics test equipment Tensile, flexural and compression types (constant rate of traverse) SpecificationISO 18899:2013, Rubber Guide to the calibration of test equipmentISO 23529:2010, Rubber General procedures for preparing and conditioning
24、test pieces for physical test methods3 PrincipleThe force required to tear across the width of a small test piece containing a slit in the centre is measured.4 Apparatus4.1 Tensile-testing machine, complying with the requirements of ISO 5893, capable of measuring force with an accuracy corresponding
25、 to class 1 as defined in ISO 5893, and with a rate of traverse of the moving grip of 500 mm/min 50 mm/min.4.2 Die, for cutting out the test piece. The construction of the die and the knife which cuts the slit are shown in Figure 1 and Figure 2.INTERNATIONAL STANDARD ISO 34-2:2015(E) ISO 2015 All ri
26、ghts reserved 1BS ISO 34-2:2015ISO 34-2:2015(E)4.3 Micrometer gauge, complying with the requirements of ISO 23529 and having a circular foot approximately 6 mm in diameter which exerts a pressure of 22 kPa 5 kPa.4.4 Travelling microscope, giving at least 10 magnification, fitted with a graticule gra
27、duated at 0,01 mm intervals.5 CalibrationThe requirements for calibration of the test apparatus are given in Annex B.6 Test pieces6.1 Shape and dimensionsThe test pieces shall be rectangular and shall conform to the dimensions shown in Figure 3 and Table 1.The test pieces shall be cut from a sheet b
28、y punching with the die (4.2), using a single blow of a mallet or (preferably) a single stroke of a press. The rubber may be wetted with water or a soap solution, and shall be supported on a sheet of slightly yielding material (for example leather, rubber belting or cardboard) on a flat, rigid surfa
29、ce.The tear strength is particularly susceptible to grain effects in the rubber. Normally, all test pieces are prepared with the grain at right angles to their length, but, in cases where grain effects are significant and are to be evaluated, two sets of test pieces shall be cut from the sheet, one
30、at right angles to the grain and the other parallel to the grain.The thickness d of the test pieces shall be 2,0 mm 0,2 mm.6.2 Measurement of dimensions6.2.1 Measurement of thicknessMeasure the thickness of the test piece by ISO 23529:2010, method A. Take at least three gauge readings in the region
31、of the slit. If an even number of readings is taken, use the average of the two median values as the result. If an odd number of readings is taken, use the median value. No reading shall deviate by more than 2 % from the value used. When the test results are to be used for comparative purposes, the
32、thickness of any test piece shall not vary by more than 10 % from the mean thickness of all the test pieces.2 ISO 2015 All rights reservedBS ISO 34-2:2015ISO 34-2:2015(E)Dimensions in millimetresNOTE b3= W w (method 2)Figure 1 Die for Delft test pieces ISO 2015 All rights reserved 3BS ISO 34-2:2015I
33、SO 34-2:2015(E)Dimensions in millimetresa) Enlarged detail of blade for cutting out test pieceb) Enlarged detail of small blade for cutting slitNOTE Cutting edge.Figure 2 Details of Delft test piece die cutting edgesKeyaSlit to be symmetrical with the width.Figure 3 Test pieceTable 1 Dimensions of t
34、est pieceDimensionValue mmL Length 60B Width 9,0 0,1b Slit length 5,0 0,16.2.2 Measurement of the total width outside the slit6.2.2.1 GeneralThe total width outside the slit b3corresponds to the rubber to be torn.4 ISO 2015 All rights reservedBS ISO 34-2:2015ISO 34-2:2015(E)Two methods of measuremen
35、t may be used. Method 1 is theoretically more exact, but is difficult to use in practice. Method 2, which is in common use, is simpler but can give different results. Unless otherwise specified, use method 2.Results obtained using test pieces measured by different methods shall not be compared.6.2.2
36、.2 Method 1: Measurement by travelling microscopeVariations occur in the length of the slit and in the total width of the test piece when the same die is used to prepare test pieces from rubber of different hardnesses. Moreover, the slit might not be uniform throughout its depth, but might be wider
37、at one surface. Take one test piece which has been cut out with the die, therefore, and use it to measure the width to be torn by cutting the test piece through with a sharp razor blade in the plane of the slit and measuring the cut surfaces (width on either side of the slit) with a travelling micro
38、scope. The ends of the slit are curved as shown in Figure 4, and an attempt shall be made to allow for this curvature when measuring the width on either side of the slit, as follows.Take as the width on the left-hand side b1, which is the distance from the line AB to an imaginary line AB which is si
39、tuated so that the total area S1+ S2= S3.Similarly, on the right-hand side, imagine a line CD situated so that the total area S1 + S2 = S3 and b2is the width.The total width b3outside the slit (i.e. the rubber to be torn) is then b1+ b2.Dimensions in millimetresKeyaTopbBottomNOTE b3= b1+b2(method 1)
40、.Figure 4 Section through slit in Delft test piece6.2.2.3 Method 2 (simpler): Measurement from the dimensions of the die used to cut the test pieceCalculate b3from the dimensions of the die (see Figure 1), using Formula (1):bWw3= (1)whereW is the measured distance between the cutting edges of the di
41、e;w is the measured width of the blade for cutting the slit. ISO 2015 All rights reserved 5BS ISO 34-2:2015ISO 34-2:2015(E)6.3 Time interval between vulcanization and testingThe time between vulcanization and testing shall be in accordance with ISO 23529.6.4 NumberAt least three and preferably six t
42、est pieces shall be tested.7 Temperature of testThe test is normally carried out at a standard laboratory temperature as specified in ISO 23529.If the test is to be carried out at a temperature other than a standard laboratory temperature, condition the test piece, immediately prior to testing, for
43、a period sufficient for it to reach substantial temperature equilibrium at the test temperature. Keep this period as short as possible in order to avoid ageing the rubber (see ISO 23529).Use the same temperature throughout any one test, as well as any series of tests intended to be comparable.8 Proc
44、edureMount the test piece in the testing machine so that the free length between the points of contact of the grips on the test piece is 30 mm, i.e. so that each grip is 15 mm from the slit. Stretch the test piece in the machine. Do not interrupt the stretching before the test piece has torn complet
45、ely through. Note the maximum force reached during tearing.9 Expression of resultsThe tearing force depends on the thickness of the test piece and the width of the rubber torn, and the result is therefore expressed as the force necessary to tear a test piece of standard width and thickness. This val
46、ue, the tear strength F0,in newtons, is given in Formula (2):FFbd038= (2)where8 is the product of the nominal values of b3(4 mm) and d (2 mm);F is the force, in newtons, required to tear the test piece;b3is the actual width, in millimetres, of the rubber torn in the test piece (see 6.2);d is the act
47、ual thickness, in millimetres, of the test piece.Arrange the results in order of increasing value and take as the result the average of the two median values if the number of test pieces is even, or the median value if the number of test pieces is odd. If only three test pieces are tested, give the
48、individual results.10 PrecisionSee Annex A.6 ISO 2015 All rights reservedBS ISO 34-2:2015ISO 34-2:2015(E)11 Test reportThe test report shall include at least the following information:a) full description of the sample and its origin;b) a reference number of this part of ISO 34, i.e. ISO 34-2:2015;c)
49、 test details:1) number of test pieces tested,2) median thickness of each test piece, calculated in accordance with 6.2.1,3) total width of each test piece outside the slit,4) method of measurement of the total width outside the slit,5) time and temperature of conditioning prior to the test,6) temperature at which the test was carried out,7) direction of the grain in the test pieces relative to that of the applied force,8) any special tearing behaviour of the test pieces noted during the test
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