1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 3781:2011Paper and board Determination of tensilestrength after immersion inwaterBS ISO 3781:2011 BRITISH STANDARDNational forewordThis British Standard is the UK implemen
2、tation of ISO 3781:2011. Itsupersedes BS 2922-2:1984 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee PAI/11, Methods of test for paper, board and pulps.A list of organizations represented on this committee can beobtained on request to its secretary.This
3、 publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2011ISBN 978 0 580 70771 1ICS 85.060Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the
4、authority of theStandards Policy and Strategy Committee on 30 September 2011.Amendments issued since publicationDate Text affectedBS ISO 3781:2011Reference numberISO 3781:2011(E)ISO 2011INTERNATIONAL STANDARD ISO3781Third edition2011-09-01Paper and board Determination of tensile strength after immer
5、sion in water Papier et carton Dtermination de la rsistance la traction aprs immersion dans leau BS ISO 3781:2011ISO 3781:2011(E) COPYRIGHT PROTECTED DOCUMENT ISO 2011 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any mea
6、ns, 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. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyr
7、ightiso.org Web www.iso.org Published in Switzerland ii ISO 2011 All rights reservedBS ISO 3781:2011ISO 3781:2011(E) ISO 2011 All rights reserved iiiForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work
8、of preparing 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-government
9、al, in liaison 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 mai
10、n task of 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. Att
11、ention 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 or all such patent rights. ISO 3781 was prepared by Technical Committee ISO/TC 6, Paper, board and pulps, Subcommittee SC 2, Test m
12、ethods and quality specifications for paper and board. This third edition cancels and replaces the second edition (ISO 3781:1983), of which it constitutes a minor revision. It is no longer applicable to tissue paper or tissue products, which are covered by ISO 12625-5. In addition, precision data ha
13、ve been added. BS ISO 3781:2011BS ISO 3781:2011INTERNATIONAL STANDARD ISO 3781:2011(E) ISO 2011 All rights reserved 1Paper and board Determination of tensile strength after immersion in water 1 Scope This International Standard specifies a test method for the determination of the wet tensile strengt
14、h of paper or board after its immersion in water for a specified period. In principle, the method is applicable to both paper and board, provided an appropriate soaking time is agreed between the interested parties. This International Standard is not applicable to tissue paper and tissue products or
15、 other lightweight, highly absorbent paper which is difficult to handle or of low strength when wet (see ISO 12625-51). NOTE The tensile strength testing is performed using an apparatus operating at a constant rate of elongation of 20 mm/min, as per ISO 1924-2, or 100 mm/min, as per ISO 1924-3. Ther
16、efore, depending on which method is chosen, only one or the other of those International Standards is needed for performing the test. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies
17、. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 186, Paper and board Sampling to determine average quality ISO 187, Paper, board and pulps Standard atmosphere for conditioning and testing and procedure for monitoring the atmosphere and
18、conditioning of samples ISO 1924-2, Paper and board Determination of tensile properties Part 2: Constant rate of elongation method (20 mm/min) ISO 1924-3, Paper and board Determination of tensile properties Part 3: Constant rate of elongation method (100 mm/min) ISO 14487, Pulps Standard water for p
19、hysical testing 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 wet tensile strength maximum tensile force per unit width that a test piece soaked with water will withstand before breaking in a tensile test ISO 12625-5:2005, definition 3.1 BS
20、 ISO 3781:2011ISO 3781:2011(E) 2 ISO 2011 All rights reservedNOTE It is expressed in kilonewtons per metre. 3.2 wet tensile strength retention ratio of the tensile strength of a wet test piece to that of another test piece from the same sample in the dry, conditioned state NOTE 1 It is expressed as
21、a percentage. NOTE 2 Adapted from ISO 12625-5:2005, definition 3.2. 4 Principle Immersion in water, for an appropriate period of time, of a test piece of the paper or board being tested, and determination of its wet tensile strength. From the wet tensile strength and the tensile strength in the dry,
22、 conditioned state, the wet tensile strength retention is calculated. 5 Apparatus 5.1 Tensile strength testing apparatus, complying with ISO 1924-2 or ISO 1924-3 for dry tensile strength testing. 5.2 Water for soaking: distilled or deionized water as specified in ISO 14487, having the temperature sp
23、ecified for conditioning in ISO 187. 6 Sampling If the tests are made to evaluate a lot, select the sample in accordance with ISO 186. If the tests are made on another type of sample, ensure that the test pieces taken are representative of the sample received. 7 Conditioning For testing of dry tensi
24、le strength and for tests which involve soaking for less than 1 h, the specimen and the test pieces shall be conditioned in accordance with ISO 187. Conditioning is not necessary for tests involving soaking for 1 h or longer. If the material has been specially treated (for example, with urea-formald
25、ehyde), care shall be taken to ensure that sufficient time has elapsed after treatment to allow the wet strength to be fully developed before soaking the test pieces. 8 Preparation of test pieces Depending on the method chosen, using an apparatus operating at a constant rate of elongation of 20 mm/m
26、in or 100 mm/min, prepare test pieces in accordance with ISO 1924-2 or ISO 1924-3 respectively. Prepare a sufficient number of test pieces to enable ten valid wet tensile strength readings in the machine direction (MD) and ten valid readings in the cross direction (CD). If the wet tensile strength r
27、etention is also to be calculated, then ten additional test pieces for determination of the dry tensile strength in the MD and another ten for the CD are required. BS ISO 3781:2011ISO 3781:2011(E) ISO 2011 All rights reserved 39 Procedure In the absence of any agreement to the contrary, soak the tes
28、t pieces until saturated; normally, this means a soaking time of 1 h. Use water (5.2) and a suitable shallow dish. Boards and other hard-sized papers may require a soaking time of 24 h or longer to attain a satisfactory degree of saturation. The appropriate soaking time may be selected to simulate p
29、articular conditions of use, by agreement between the interested parties. For very absorbent papers, it is recommended that only the centre portion of the test piece be wetted, while the portion held by the clamps remains dry (see ISO 12625-51). After soaking, remove the test pieces from the dish. L
30、ightly blot the first test piece in order to remove surplus water and immediately test it by the method specified in ISO 1924-2 or ISO 1924-3. Repeat for the remaining test pieces. Carry out ten tests in the MD and ten in the CD of the immersed test pieces. If the wet tensile strength retention is a
31、lso to be calculated, carry out ten additional tests in the MD and another ten in the CD of the dry, conditioned test pieces. 10 Calculation and expression of results 10.1 General Calculate and report the wet tensile strength and, if required, the wet tensile strength retention separately for the MD
32、 and CD, as follows. 10.2 Wet tensile strength Calculate the wet tensile strength, wet, using Equation (1): wetwetFb (1) where wetF is the mean maximum tensile force, in kilonewtons; b is the width of the dry test piece (15 mm), in metres. Report the wet tensile strength, in kilonewtons per metre, t
33、o three significant figures. 10.3 Wet tensile strength retention If required, calculate the wet tensile strength retention, R, as a percentage of the corresponding value in the dry state using Equation (2): wetRdry100 (2) where wetis the wet tensile strength, in kilonewtons per metre; BS ISO 3781:20
34、11ISO 3781:2011(E) 4 ISO 2011 All rights reserveddryis the tensile strength in the dry, conditioned state, in kilonewtons per metre. NOTE The calculations for dry tensile strength are given in ISO 1924-2 or ISO 1924-3. 11 Test report The test report shall include the following information: a) refere
35、nce to this International Standard, i.e. ISO 3781; b) the date and place of testing; c) the complete identification of the sample; d) the soaking time and, if the sample has been conditioned, the conditioning atmosphere used; e) the International Standard used for tensile strength testing, i.e. ISO
36、1924-2 or ISO 1924-3; f) the wet tensile strength calculated in accordance with 10.2; g) if required, the wet tensile strength retention in accordance with 10.3; h) any deviation from this International Standard or any other circumstance that might have influenced the results. BS ISO 3781:2011ISO 37
37、81:2011(E) ISO 2011 All rights reserved 5Annex A (informative) Precision data The estimates of repeatability and reproducibility are based on data from the CEPI-CTS (Confederation of European Paper Industries Comparative Testing Service) round 2 in 2010. The calculations have been made according to
38、ISO/TR 24498 2and TAPPI Test method T 1200 sp-07 3. The repeatability limit, r, can be calculated from within lab1, 9 6 2rs . The reproducibility limit, R, can be calculated as 22within lab between lab1, 9 6 2Rss . The repeatability standard deviation reported in Table A.1 is the “pooled” repeatabil
39、ity standard deviation, i.e. the standard deviation is calculated as the root-mean-square of the standard deviations of the participating laboratories. This differs from the conventional definition of repeatability in ISO 5725-14. The repeatability and reproducibility (see Table A.2) limits reported
40、 are estimates of the maximum difference which should be expected in 19 of 20 instances, when comparing two test results for material similar to those described under similar test conditions. These estimates may not be valid for different materials or different test conditions. Repeatability and rep
41、roducibility limits are calculated by multiplying the repeatability and reproducibility standard deviations by 2,77. NOTE 2,77 1,96 2 , provided that the test results have a normal distribution and that the standard deviation, s, is based on a large number of tests. Table A.1 Estimation of repeatabi
42、lity of the test method from CEPI-CTS Material Number of laboratories Mean value N/m Standard deviation, srN/m Coefficient of variation, CoVr% Repeatability limit, r N/m Sample level 1 10 531 26,6 5,0 73,7 Sample level 2 10 1 777 67,0 3,8 185,7Table A.2 Estimation of reproducibility of the test meth
43、od from CEPI-CTS Material Number of laboratories Mean value, N/m Standard deviation, sRN/m Coefficient of variation, CoVR% Reproducibility limit, R N/m Sample level 1 10 531 37,3 7,0 103,5Sample level 2 10 1 777 81,3 4,6 225,3 BS ISO 3781:2011ISO 3781:2011(E) 6 ISO 2011 All rights reservedBibliograp
44、hy 1 ISO 12625-5, Tissue paper and tissue products Part 5: Determination of wet tensile strength 2 ISO/TR 24498:2006, Paper, board and pulps Estimation of uncertainty for test methods 3 TAPPI Test method T 1200 sp-07, Interlaboratory evaluation of test methods to determine TAPPI repeatability and re
45、producibility 4 ISO 5725-1:1994, Accuracy (trueness and precision) of measurement methods and results Part 1: General principles and definitions BS ISO 3781:2011BS ISO 3781:2011ISO 3781:2011(E) ICS 85.060 Price based on 6 pages ISO 2011 All rights reserved This page deliberately left blankBSI is the
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