ISO-22088-2-2006.pdf

Reference number ISO 22088-2:2006(E) © ISO 2006 INTERNATIONAL STANDARD ISO 22088-2 First edition 2006-08-15 Plastics Determination of resistance to environmental stress cracking (ESC) Part 2: Constant tensile load method Plastiques Détermination de la fissuration sous contrainte dans un environnement donné (ESC) Partie 2: Méthode sous contrainte de traction constante Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:45:20 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22088-2:2006(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. © ISO 2006 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISO's 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 copyrightiso.org Web www.iso.org Published in Switzerland ii © ISO 2006 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:45:20 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22088-2:2006(E) © ISO 2006 All rights reserved iii Contents Page Foreword iv 1 Scope . 1 2 Normative references. 1 3 Principle. 2 4 Apparatus 2 5 Conditioning and test conditions 3 5.1 Conditioning 3 5.2 Test temperature. 3 5.3 Test medium 3 6 Test stress. 4 6.1 Maximum permissible stress. 4 6.2 Method A 4 6.3 Method B 4 6.4 Method C 4 7 Test specimens. 4 7.1 General. 4 7.2 Shape and dimensions. 4 7.3 Number 5 7.4 Preparation 5 8 Procedure 6 9 Expression of results . 7 9.1 Method A 7 9.2 Method B 7 9.3 Method C 7 10 Precision 7 11 Test report . 8 Annex A (informative) Examples of stresses to be applied. 9 Bibliography. 10 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:45:20 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22088-2:2006(E) iv © ISO 2006 All rights reserved 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. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main 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. 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 or all such patent rights. ISO 22088-2 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 6, Ageing, chemical and environmental resistance. It cancels and replaces ISO 6252:1992, which has been technically revised. ISO 22088 consists of the following parts, under the general title Plastics Determination of resistance to environmental stress cracking (ESC): Part 1: General guidance Part 2: Constant tensile load method (replacement of ISO 6252:1992) Part 3: Bent strip method (replacement of ISO 4599:1986) Part 4: Ball or pin impression method (replacement of ISO 4600:1992) Part 5: Constant tensile deformation method (new test method) Part 6: Slow strain rate method (new test method) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:45:20 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 22088-2:2006(E) © ISO 2006 All rights reserved 1 Plastics Determination of resistance to environmental stress cracking (ESC) Part 2: Constant tensile load method 1 Scope This part of ISO 22088 specifies methods for the determination of environmental stress cracking (ESC) of thermoplastics when they are subjected to a constant tensile load in the presence of chemical agents. It is applicable to test specimens prepared by moulding and/or machining and can be used both for the assessment of ESC of plastic materials exposed to different environments, and for the determination of ESC of different plastic materials exposed to a specific environment. This is essentially a ranking test and is not intended to provide data to be used for design or performance prediction. NOTE Methods for the determination of environmental stress cracking by means of a constant-strain test are specified in ISO 22088-3, ISO 22088-4 and ISO 22088-5. 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 document (including any amendments) applies. ISO 293, Plastics Compression moulding of test specimens of thermoplastic materials ISO 294-1, Plastics Injection moulding of test specimens of thermoplastic materials Part 1: General principles, and moulding of multipurpose and bar test specimens ISO 527-2:1993, Plastics Determination of tensile properties Part 2: Test conditions for moulding and extrusion plastics ISO 2818, Plastics Preparation of test specimens by machining ISO 3167, Plastics Multipurpose test specimens ISO 22088-1:2006, Plastics Determination of resistance to environmental stress cracking (ESC) Part 1: General guidance Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:45:20 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22088-2:2006(E) 2 © ISO 2006 All rights reserved 3 Principle A test specimen is subjected to a constant tensile load, corresponding to a stress lower than that at yield, while immersed in a specified environment at the temperature selected for testing. The time and/or stress at which the specimen breaks is recorded. The environmental stress cracking of the test specimens is determined by one of the following methods (A, B or C), depending upon the time to rupture: Method A: Determination of the tensile stress leading to rupture at 100 h. This stress is obtained by interpolation of the graph of time to rupture versus applied tensile stress. Method B: Determination of the time to rupture under a specified tensile stress. This method is used when the time to rupture exceeds 100 h. Method C: Determination of the time to rupture for a series of applied stresses. The graph of time to rupture versus applied stress is then examined to determine if the rupture time for some agreed-upon applied stress is satisfactory. 4 Apparatus 4.1 Test device, allowing test specimens to be simultaneously subjected to a tensile load and exposed to a chemical environment. If the chemical is a liquid at the test temperature, the test specimen shall be completely immersed. If it is highly viscous at the test temperature, the specimen may be covered with a coating of the agent at least 2 mm thick (see Clause 5). Parts of the device that come into contact with the test medium shall be made of an inert material. The constant tensile load may be applied with weights (Figure 1 is a schematic diagram of a suitable apparatus). The force shall be accurate to ± 1 % of the specified force. It is important to ensure that there is no unintended contact between moving parts, and that all moving parts of the apparatus are properly maintained and lubricated as appropriate. If the test device has several test stations, means shall be provided to prevent the vibration occurring through failure at one station from being transmitted to the whole system. Unless otherwise specified, forces shall be applied parallel to the longitudinal axis. NOTE Bending or twisting forces will produce different stresses and may affect the results and increase test variability. 4.2 Temperature-controlled bath or room, allowing the containers to be maintained at (23 ± 2) °C or at a higher test temperature up to (105 ± 2) °C (see 5.2). 4.3 Automatic timer, as shown schematically in Figure 1, to measure the time to rupture of each specimen to within ± 1 % of the elapsed time. 4.4 Equipment for the preparation of test specimens by moulding (see ISO 293 and ISO 294-1), machining (see ISO 2818) or die cutting. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:45:20 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22088-2:2006(E) © ISO 2006 All rights reserved 3 Key 1 balance 2 frictionless bearing, or knife edge 3 wire attachment point 4 wire 5 circulation of temperature-controlled liquid 6 clamps 7 test specimen 8 chemical environment 9 weights 10 switch controlling timer 11 timer Figure 1 One type of apparatus for measuring fracture under constant load 5 Conditioning and test conditions 5.1 Conditioning Unless otherwise agreed between the interested parties, the test specimens shall be conditioned before testing for at least 24 h at (23 ± 2) °C and (50 ± 10) % relative humidity. 5.2 Test temperature The preferred test temperatures are (23 ± 2) °C and (55 ± 2) °C. If required, other temperatures may be used, preferably selected from the following: (40 ± 2) °C, (70 ± 2) °C, (85 ± 2) °C, (100 ± 2) °C or as agreed upon by the interested parties. 5.3 Test medium See ISO 22088-1:2006, 7.3. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:45:20 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22088-2:2006(E) 4 © ISO 2006 All rights reserved 6 Test stress 6.1 Maximum permissible stress The stress applied to the test specimen during the test shall be less than the tensile stress at yield of the material at the temperature of the test. NOTE As a general guide, the stress that produces an elongation of 2 % after 1 h can be taken as the maximum permissible stress. This stress can be determined by preliminary tests using several different stresses. 6.2 Method A Conduct tests at a series of applied stress levels to determine the applied stress that will cause failure in 100 h. Test a minimum of five specimens at each applied stress. The applied stress needed to produce failure in 100 h is calculated as described in 9.1. 6.3 Method B Determine the time to rupture under a single stress agreed between the interested parties, but not higher than the maximum permissible stress defined in 6.1. 6.4 Method C Determine the times to rupture for agreed-upon applied stresses. The series of stresses shall be chosen in accordance with 8.7. Test a minimum of two specimens at each applied stress. The result is reported as the time to rupture for a particular applied stress. Method A is a subset of method C. 7 Test specimens 7.1 General When moulding test specimens, or when machining and polishing test specimens cut from large sheets or products, it is important to minimize any residual stress. Use the mildest conditions possible during specimen preparation. Annealing specimens prior to testing is recommended. Report the exact conditions used for specimen preparation and the conditions used for any annealing of specimens prior to testing. 7.2 Shape and dimensions Wherever possible, use the type 1BA small test specimen specified in Annex A of ISO 527-2:1993, as shown in Figure 2. The preferred thickness is (2 ± 0,2) mm, but when the test specimens are prepared from finished products the thickness may be that of the product. Alternatively, a type 1BA specimen 3 mm to 4 mm thick may be used. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 07:45:20 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22088-2:2006(E) © ISO 2006 All rights reserved 5 Key l3 overall length: 75 mm b2 width at ends: (10 ± 0,5) mm l1 length of narrow, parallel-sided portion: (30 ± 0,5) mm b1 width of narrow, parallel-sided portion: (5 ± 0,5) mm r radius, minimum: 30 mm h thickness: preferably (2 ± 0,2) mm l0 distance between gauge marks: 25 mm l2 initial distance between grips: 57 mm Figure 2 ISO 527-2 type 1BA specimen (type 1B scaled down 2:1) 7.3 Number At least five specimens shall be tested at each tensile stress in the case of methods A and B, and at least two specimens for each stress in the case of method C. If the material is thought to be anisotropic, two sets of specimens s