《BS-ISO-188-2007.pdf》由会员分享，可在线阅读，更多相关《BS-ISO-188-2007.pdf（26页珍藏版）》请在三一文库上搜索。
1、BRITISH STANDARD BS ISO 188:2007 Rubber, vulcanized or thermoplastic Accelerated ageing and heat resistance tests ICS 83.060 ? Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:50:07 GMT+00:00 2007, Uncontrolled Copy, (c) BSI BS ISO 188:2007 This British Standa
2、rd was published under the authority of the Standards Policy and Strategy Committee on 31 August 2007 BSI 2007 ISBN 978 0 580 55155 0 National foreword This British Standard is the UK implementation of ISO 188:2007. It supersedes BS ISO 188:1998 which is withdrawn. The UK participation in its prepar
3、ation 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. Users are responsible for its cor
4、rect application. Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:50:07 GMT+00:00 2007, Uncontrolled Copy, (c) BSI Refe
5、rence number ISO 188:2007(E) INTERNATIONAL STANDARD ISO 188 Fourth edition 2007-06-01 Rubber, vulcanized or thermoplastic Accelerated ageing and heat resistance tests Caoutchouc vulcanis ou thermoplastique Essais de rsistance au vieillissement acclr et la chaleur BS ISO 188:2007 Licensed Copy: Londo
6、n South Bank University, London South Bank University, Sat Aug 18 09:50:07 GMT+00:00 2007, Uncontrolled Copy, (c) BSI ii Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:50:07 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iii Contents Page Foreword iv Introductio
7、n v 1 Scope . 1 2 Normative references. 1 3 Principle. 1 4 Apparatus 2 5 Test pieces 4 6 Time interval between vulcanization and testing 5 7 Ageing conditions (duration and temperature) . 5 8 Procedure 6 9 Expression of results . 6 10 Precision 6 11 Test report . 6 Annex A (informative) Determinatio
8、n of the air speed in ovens with forced air circulation 8 Annex B (informative) Precision. 10 Annex C (informative) Guidance for using precision results 17 BS ISO 188:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:50:07 GMT+00:00 2007, Uncontrolled Copy
9、, (c) BSI iv 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
10、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) o
11、n 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
12、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
13、 responsible for identifying any or all such patent rights. ISO 188 was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 2, Testing and analysis. This fourth edition cancels and replaces the third edition (ISO 188:1998), which has been technically revised. It al
14、so incorporates the Technical Corrigendum ISO 188:1998/Cor.1:2003. The revision includes the deletion of method C (ageing under oxygen pressure) since it is a dangerous test and has no correlation with natural ageing. In addition, precision data from a second interlaboratory test programme (ITP) hav
15、e been added and some of the data from the first ITP corrected (affecting, in particular, certain of the absolute mean and relative precision values). BS ISO 188:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:50:07 GMT+00:00 2007, Uncontrolled Copy, (c)
16、 BSI v Introduction Accelerated ageing and heat resistance tests are designed to estimate the relative resistance of rubber to deterioration with the passage of time. For this purpose, the rubber is subjected to controlled deteriorating influences for definite periods, after which appropriate proper
17、ties are measured and compared with the corresponding properties of the unaged rubber. In accelerated ageing, the rubber is subjected to a test environment intended to produce the effect of natural ageing in a shorter time. In the case of heat resistance tests, the rubber is subjected to prolonged p
18、eriods at the same temperature as that which it will experience in service. Two types of method are given in this International Standard, namely an air-oven method using a low air speed and an air-oven method using forced air ventilation for a high air speed. The selection of the time, temperature a
19、nd atmosphere to which the test pieces are exposed and the type of oven to use will depend on the purpose of the test and the type of polymer. In air-oven methods, deterioration is accelerated by raising the temperature. The degree of acceleration thus produced varies from one rubber to another and
20、from one property to another. Degradation can also be accelerated by air speed. Consequently, ageing with different ovens can give different results. Consequences of these effects are: a) Accelerated ageing does not truly reproduce under all circumstances the changes produced by natural ageing. b) A
21、ccelerated ageing sometimes fails to indicate accurately the relative natural or service life of different rubbers; thus, ageing at temperatures greatly above ambient or service temperatures may tend to equalize the apparent lives of rubbers, which deteriorate at different rates in storage or servic
22、e. Ageing at one or more intermediate temperatures is useful in assessing the reliability of accelerated ageing at high temperatures. c) Accelerated ageing tests involving different properties may not give agreement in assessing the relative lives of different rubbers and may even arrange them in di
23、fferent orders of merit. Therefore, deterioration should be measured by the changes in property or properties which are of practical importance, provided that they can be measured reasonably accurately. Air-oven ageing should not be used to simulate natural ageing which occurs in the presence of eit
24、her light or ozone when the rubbers are stretched. To estimate lifetime or maximum temperature of use, tests can be performed at several temperatures and the results can be evaluated by using an Arrhenius plot or the Williams Landel Ferry (WLF) equation as described in ISO 11346, Rubber, vulcanized
25、or thermoplastic Estimation of life-time and maximum temperature of use. BS ISO 188:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:50:07 GMT+00:00 2007, Uncontrolled Copy, (c) BSI blank Licensed Copy: London South Bank University, London South Bank Univ
26、ersity, Sat Aug 18 09:50:07 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 1 Rubber, vulcanized or thermoplastic Accelerated ageing and heat resistance tests WARNING Persons using this International Standard should be familiar with normal laboratory practice. This standard does not purport to address al
27、l 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 This International Standard specifies accelerated ageing or heat resistance t
28、ests on vulcanized or thermoplastic rubbers. Two methods are given: Method A: air-oven method using a cell-type oven or cabinet oven with low air speed and a ventilation of 3 to 10 changes per hour; Method B: air-oven method using a cabinet oven with forced air circulation by means of a fan and a ve
29、ntilation of 3 to 10 changes per hour. 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 amendmen
30、ts) applies. ISO 37, Rubber, vulcanized or thermoplastic Determination of tensile stress-strain properties ISO 48, Rubber, vulcanized or thermoplastic Determination of hardness (hardness between 10 IRHD and 100 IRHD) ISO/TR 9272, Rubber and rubber products Determination of precision for test method
31、standards ISO 23529, Rubber General procedures for preparing and conditioning test pieces for physical test methods 3 Principle 3.1 General Test pieces are subjected to controlled deterioration by air at an elevated temperature and at atmospheric pressure, after which specified properties are measur
32、ed and compared with those of unaged test pieces. The physical properties concerned in the service application should be used to determine the degree of deterioration but, in the absence of any indication of these properties, it is recommended that tensile strength, stress at intermediate elongation
33、, elongation at break (in accordance with ISO 37) and hardness (in accordance with ISO 48) be measured. BS ISO 188:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:50:07 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 2 3.2 Accelerated ageing by heating in air
34、 In this method, the test pieces are subjected to a higher temperature than the rubber would experience in service in order to produce the effects of natural ageing in a shorter time. 3.3 Heat resistance test In this method, the test pieces are subjected to the same temperature as they would experie
35、nce in service. 4 Apparatus 4.1 Air oven 4.1.1 General The oven shall be of such a size that the total volume of the test pieces does not exceed 10 % of the free space in the oven. Provision shall be made for suspending test pieces so that they are at least 10 mm from each other and, in cabinet oven
36、s and ovens with forced air circulation, at least 50 mm from the sides of the oven. The temperature of the oven shall be controlled so that the temperature of the test pieces is kept within the specified tolerance for the specified ageing temperature (see Clause 7) for the whole ageing period. A tem
37、perature sensor shall be placed inside the heating chamber close to the samples to record the actual ageing temperature. No copper or copper alloys shall be used in the construction of the heating chamber. Provision shall be made for a slow flow of air through the oven of not less than three and not
38、 more than ten air changes per hour. Care shall be taken to ensure that the incoming air is heated to within 1 C of the temperature of the oven before coming in contact with the test pieces. The ventilation (or air change rate) can be determined by measuring the volume of the oven chamber and the fl
39、ow of air through the chamber. NOTE To ensure good precision when doing ageing and heat resistance tests, it is very important to keep the temperature uniform and stable during the test and to verify that the oven used is within the temperature limits with regard to time and space. Increasing the ai
40、r speed in the oven improves temperature homogeneity. However, air circulation in the oven and ventilation influence the ageing results. With a low air speed, accumulation of degradation products and evaporated ingredients, as well as oxygen depletion, can take place. A high air speed increases the
41、rate of deterioration, due to increased oxidation and volatilization of plasticizers and antioxidants. 4.1.2 Cell-type oven The oven shall consist of one or more vertical cylindrical cells having a minimum height of 300 mm. The cells shall be surrounded by a thermostatically controlled good-heat-tra
42、nsfer medium (aluminium block, liquid bath or saturated vapour). Air passing through one cell shall not enter other cells. Provision shall be made for a slow flow of air through the cell. The air speed shall depend on the air change rate only. 4.1.3 Cabinet oven This shall comprise a single chamber
43、without separating walls. Provision shall be made for a slow flow of air through the oven. The air speed shall depend on the air change rate only, and no fans are allowed inside the heating chamber. BS ISO 188:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18
44、 09:50:07 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 3 4.1.4 Oven with forced air circulation Either of the following two types shall be used: a) Type 1 oven with laminar air flow (see Figure 1). The air flow through the heating chamber shall be as uniform and laminar as possible. The test pieces sh
45、all be placed with the smallest surface facing towards the air flow to avoid disturbing the air flow. The air speed shall be between 0,5 m/s and 1,5 m/s. The air speed near the test pieces can be measured by means of an anemometer. Key 1 test pieces 2 laminar air flow 3 heating element 4 air inlet 5
46、 air blower 6 air outlet Figure 1 Type 1 oven with laminar air flow b) Type 2 oven with turbulent air flow (see Figure 2). The air entering from a side-wall air-inlet into the heating chamber is turbulent around the test pieces, which are suspended on a carrier rotating at a speed of five to ten rot
47、ations per minute so that they are exposed to the heating air as uniformly as possible. The average air speed shall be 0,5 m/s 0,25 m/s. The average air speed near the test pieces can be calculated from measurements made with an anemometer at nine different positions (see Figure A.1 in Annex A). A s
48、uitable method of measurement is described in Annex A. BS ISO 188:2007 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:50:07 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 4 Key 1 test piece carrier 2 test pieces 3 turbulent air flow 4 laminar air flow (inlet, ou
49、tlet and near to wall) 5 heating element 6 motor 7 air inlet 8 air blower 9 air outlet Figure 2 Type 2 oven with turbulent air flow 5 Test pieces It is recommended that the accelerated ageing or heat resistance test be carried out on test pieces prepared and conditioned as required for the appropriate property tests, and not on complete products or sample sheets, and that their form be such that no mechanical, chemical or heat treatment will be required after ageing. Only test piece