Rubber, vulcanized or thermoplastic - Accelerated ageing and heat resistance tests - Air-oven method
WARNING: Persons using this standard shall 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
This standard is applicable to the accelerated ageing with hot air and heat resistance test of vulcanized rubber or thermoplastic rubber under normal pressure.
2 Normative references
The following standards contain provisions which, through reference in this standard, constitute provisions of this standard. At time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.
GB/T 2941-1991 Rubber - Standard temperatures, humidities and times for the conditioning environmental and testing of test pieces (eqv ISO 471: 1983)
GB/T 9865.1-1996 Rubber, vulcanized or thermoplastic - Preparation of samples and test pieces - Part 1: Physical tests (idt ISO 4661-1: 1993)
GB/T 14838-1993 Rubber and rubber products - Determination of precision for test method standards (neq ISO/TR 9272: 1986)
3 Principle
The properties of test piece are measured after ageing in air at high temperature and atmospheric pressure, and compared with those of unaged test pieces.
The physical properties concerned in the service application shall be used to determine the degree of ageing, but in the absence of any indication of these properties, it is recommended to measure tensile strength, stress at intermediate elongation, elongation at break and hardness.
3.1 Accelerated ageing with hot air
In this test method, the oxygen concentration is low, and even if oxidation is rapid, oxygen may not diffuse into the rubber quickly enough to maintain uniform oxidation. This ageing method is therefore liable to give misleading results with poor-ageing rubbers when the normal thickness specified in the specified in the standard test method appropriate to the test method is used.
3.2 Heat resistance test
In this test method, the test pieces are subjected to the same temperature as they would experience in service, and after definite periods, appropriate properties are measured and compared with those of the unaged rubber.
Foreword
1 Scope
2 Normative references
3 Principle
4 Test apparatus
5 Test pieces
6 Time interval between vulcanization and test
7 Test conditions
8 Procedure
9 Expression of results
10 Precision
11 Test report
Annex A (Informative) Guidance for using precision results
