National foreword

This British Standard is the UK implementation of ISO 188:2023. It supersedes BS ISO 188:2011, which is withdrawn.

The UK participation in its preparation was entrusted to Technical Committee PRI/22, Testing and analysis of rubber.

A list of organizations represented on this committee can be obtained on request to its committee manager.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 March 2023.

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.

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. 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 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 users and does not constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products, Subcommittee SC 2, Testing and analysis.

This sixth edition cancels and replaces the fifth edition (ISO 188:2011), which has been technically revised.

The main changes are as follows:

add oven type with a forced air circulation and high air speed/air exchange rate;
editorial changes for better understanding.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

Accelerated ageing and heat resistance tests are used to determine the change of defined properties of rubber and thermoplastic elastomers over a specified period. These properties are compared before and after the accelerated ageing and heat resistance tests.

In accelerated ageing, the rubber is exposed to an elevated temperature with the intention to simulate the effect of natural ageing in a shorter time. The degree of acceleration depends on the tested material as well as to the property being evaluated.

In the case of heat resistance tests, the rubber is exposed to prolonged periods at the operation temperature of the material.

Two types of ovens are specified in this document, cell ovens and cabinet ovens. Cabinet ovens can be of four types as described in Clause 5.

The duration, temperature, and atmosphere to which the test pieces are exposed and the type of oven to use depends on the purpose of the test and the type of polymer.

The change of properties not only depends on the temperature but can also depend on the air speed. Consequently, even tests at the same temperature but at different air speed (different ovens) may give different results.

Consequences of these effects are

accelerated ageing is only a simulation of the natural ageing and can therefore produce different results.
If different materials are compared, it is recommended to perform the accelerated ageing tests at more than one elevated temperature as different rubbers might show a different temperature behaviour (change of properties) at certain operation temperatures.
It is important to determine the properties of the rubber for the accelerated ageing test, which are used for the intended material application. Only these properties should be used for the evaluation of the test results. If these properties give a different ranking of the materials tested, it is recommended to agree on a lead property for evaluation. It is also recommended, that all evaluated properties are measured according to an international standard or an equivalent test procedure.

Air-oven ageing should not be used to simulate natural ageing under stress (bent or stretched test pieces) and the presence of light or ozone.

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.

1 Scope

This document specifies accelerated ageing or heat resistance tests on vulcanized or thermoplastic rubbers/thermoplastic elastomers. Four methods are possible, they are detailed in Clause 5.

2 Normative references

3 Terms and definitions

4 Principle

4.1 General

4.2 Accelerated ageing test

4.3 Heat resistance test

5 Apparatus

5.1 Air oven.

5.2 Method A cell oven.

5.3 Method A cabinet oven.

5.4 Method B, C and D cabinet oven with forced air circulation.

6 Calibration

7 Test pieces

8 Time interval between vulcanization and testing

9 Ageing conditions (duration and temperature)

9.1 General

9.2 Accelerated ageing test

9.3 Heat resistance test

10 Procedure

11 Expression of results

12 Precision

13 Test report

Bibliography

BS ISO 188:2023

Rubber, vulcanized or thermoplastic. Accelerated ageing and heat resistance tests

Current

Published:

31 Mar 2023