BS-EN-ISO-1421-1998.pdf

BRITISH STANDARD BS EN ISO 1421:1998 Rubber- or plastics-coated fabrics Determination of tensile strength and elongation at break The European Standard EN ISO 1421:1998 has the status of a British Standard ICS 59.080.40 BS EN ISO 1421:1998 This British Standard, having been prepared under the direction of the Sector Board for Materials and Chemicals, was published under the authority of the Standards Board and comes into effect on 15 August 1998 © BSI 05-1999 ISBN 0 580 30085 4 National foreword This British Standard is the English language version of EN ISO 1421:1998. It is identical with ISO 1421:1998. It supersedes BS 3424-4:1982 which is withdrawn. The UK participation in its preparation was entrusted to Technical Committee TCI/78, Coated fabrics, which has the responsibility to: 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; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references Attention is drawn to the fact that CEN and CENELEC Standards normally include an annex which lists normative references to international publications with their corresponding European publications. The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN ISO title page, page 2, the ISO title page, page ii, pages 1 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.DateComments BS EN ISO 1421:1998 © BSI 05-1999i Contents Page National forewordInside front cover Foreword2 Forewordii Text of ISO 14211 ii blank EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM EN ISO 1421 June 1998 ICS Descriptors: See ISO document English version Rubber- or plastics-coated fabrics Determination of tensile strength and elongation at break (ISO 1421:1998) Supports textiles revêtus de caoutchouc ou de plastique Détermination de la force de rupture et de lallongement à la rupture (ISO 1421:1998) Mit Kautschuk oder Kunststoffe beschichtete Textilien Bestimmung der Zugfestigkeit und der Bruchdehnung (ISO 1421:1998) This European Standard was approved by CEN on 9 April 1998. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels © 1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 1421:1998 E EN ISO 1421:1998 © BSI 05-1999 2 Foreword The text of the International Standard ISO 1421:1998 has been prepared by Technical Committee ISO/TC 45 “Rubber and rubber products” in collaboration with Technical Committee CEN/TC 248 “Textiles and textile products”, the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by December 1998, and conflicting national standards shall be withdrawn at the latest by December 1998. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice The text of the International Standard ISO 1421:1998 was approved by CEN as a European Standard without any modification. NOTENormative references to International Standards are listed in Annex ZA (normative). Contents Page Foreword2 1Scope1 2Normative references1 3Definitions1 4Principle2 5Apparatus2 6Atmosphere for conditioning and testing2 7Method 1: strip test method2 8Method 2: garb test method4 Annex ZA (normative) Normative references to international publications with their relevant European publicationsInside back cover Figure 1 Maximum force at break5 Figure 2 Tensile force at break6 Figure 3 Rupture of one element of a coated fabric6 Figure 4 Example showing how test pieces may be cut out7 Figure 5 Test piece for grab test method8 EN ISO 1421:1998 ii © BSI 05-1999 Foreword 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 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-governmental, 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. 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. International Standard ISO 1421 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products. This second edition cancels and replaces the first edition (ISO 1421:1977), which has been technically revised. Descriptors: Fabrics, woven fabrics, coated fabrics, fabrics coated with rubber, fabrics coated with plastics, tests, tension tests, determination, tensile strength, elongation at break. EN ISO 1421:1998 © BSI 05-19991 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 safety and health practices and to ensure compliance with any national regulatory conditions. 1 Scope 1.1 This International Standard describes two methods for the determination of the tensile strength of fabrics coated with rubber or plastics: Method 1 the strip test method, which is a method for the determination of tensile strength and elongation at break; Method 2 the grab test method, which is a method for the determination of tensile strength only. 1.2 The methods apply to test pieces in equilibrium with specific standard atmospheres for testing, and to wet test pieces. 1.3 Both methods require the use of a constant rate of extension (CRE) tensile-testing machine. 2 Normative references The following standards contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 2231:1989, Rubber- or plastics-coated fabrics Standard atmospheres for conditioning and testing. ISO 2286-2:1998, Rubber- or plastics-coated fabrics Determination of roll characteristics Part 2: Methods for determination of total mass per unit area, mass per unit area of coating and mass per unit area of substrate. ISO 7500-1:1986, Metallic materials Verification of static uniaxial testing machines Part 1: Tensile testing machines. 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 maximum force the maximum force recorded in extending the test piece to breaking point (see Figure 1) 3.2 elongation; extension (E) the increase in length of a test piece, expressed in units of length, e.g. cm or mm 3.3 percentage elongation the elongation expressed as a percentage of the nominal gauge length 3.4 force at break the tensile force recorded at the moment of break (see Figure 2) NOTEFigure 3 corresponds to the rupture of one of the elements constituting the coated fabric. Typical examples are: a) a “rigid” polymer layer on an extensible fabric: rupture of the polymer layer; b) a very extensible, thick polymer layer on a weak, less extensible fabric or nonwoven: rupture of the woven fabric or of the nonwoven. 3.5 elongation at break the elongation of a test piece corresponding to the force at the breaking point (see Figure 2), usually expressed as a percentage of the nominal gauge length 3.6 nominal gauge length the length of a test piece under a specified pre-tension, measured from nip to nip of the jaws of the holding clamps with the clamps in their starting position NOTEThe nominal gauge length is also referred to as the initial gauge length. 3.7 elongation at maximum force the elongation of a test piece produced by the maximum force (see Figure 1) 3.8 constant rate of extension (CRE) a means of conducting a tensile test in which the rate of increase in the length of the test piece is uniform with time NOTEThe rate of increase of the force is dependent upon the extension characteristics of the test piece. EN ISO 1421:1998 2 © BSI 05-1999 3.9 strip test a tensile strength test in which the full width of the test piece is gripped in the jaws 3.10 grab test a tensile strength test in which only the central part of the width of the test piece is gripped in the jaws 4 Principle A test piece is extended at a constant rate of extension until it breaks. For method 1 (clause 7), the maximum force and the elongation at maximum force and, if required, the force at break and the elongation at break are determined. For method 2 (clause 8), the maximum force only is determined. 5 Apparatus 5.1 Constant rate of extension (CRE) tensile testing machine, having the following general characteristics: The machine shall be provided with means for reading and recording both the force applied to the test piece in stretching it to the breaking point and the corresponding extension of the test piece. It shall be provided with a strength indicator having several scales in order to ensure that the rupture of each test piece is obtained with a strength of 15 % to 85 % of the maximum of the scale used. Under conditions of use, the accuracy of the apparatus shall be class 1 as defined in ISO 7500-1. The error of the indicated or recorded maximum force at any point in the range in which the machine is used shall not exceed ± 1 %, and the error of the indicated or recorded jaw separation shall not exceed 1 mm. After the first 2 s of the test, the rate of increase in the distance between the clamps shall be uniform to within 5 %. If the force and elongation are recorded by means of data acquisition boards and software, the frequency of data collection shall be at least 8 s1. 5.2 Clamping device, with the central point of the two jaws of the machine in the line of pull, the front edges at right angles to the line of pull and their clamping faces in the same plane. The jaws shall be capable of holding the test piece without allowing it to slip. They shall be designed so that they do not damage the test piece or reduce its strength. Smooth, flat or engraved corrugated jaws can be used for clamping. Using suitable packing materials in the jaws, e.g. paper, leather, plastics or rubber, avoids difficulties in clamping in many cases. When tests are carried out and the test pieces either break at the jaws or tend to slip, the results may often be discarded. In order to obtain legitimate results by avoiding jaw breaks and the effect of slippage, the use of capstan jaws or any other self-locking device can be a suitable alternative to ordinary flat jaws. When information on strain is required, elongation measurements are made by means of an extensometer which follows the movements of two reference points on the test piece. The use of such jaws and an extensometer shall be reported in the test report (see 7.4, item k). For the strip test method, the jaws shall be not less than the width of the test piece and should preferably have a width of at least 60 mm. For the grab test method, the dimensions of one of the jaws of each clamp shall be 25 mm ± 0,5 mm by 25 mm ± 0,5 mm. The other jaw of each clamp shall be at least as wide as the one to which it is attached and should preferably be 50 mm wide. 5.3 Equipment for cutting test pieces and fraying them down to the required width. 5.4 Equipment in which the test pieces can be immersed in water prior to wet testing. 5.5 Distilled or deionized water, for wetting out the test pieces. 5.6 Wetting agent or surfactant. 6 Atmosphere for conditioning and testing The atmosphere used for conditioning and testing shall be one of those specified in ISO 2231. The sample shall be conditioned for not less than 24 h. NOTEIf the test results are to be representative of the properties of the coated fabric at the time of manufacturing and distribution, the tests must be carried out no longer than 3 months after the date of manufacture. 7 Method 1: strip test method 7.1 Sampling and preparation of test pieces From each sample, cut two sets of test pieces, one set in the longitudinal direction and the other in the transverse direction. Each set shall consis