ISO 34-1 - Rubber, Vulcanized or Thermoplastic – Determination of Tear Strength
ISO 34-1 is used to investigate the mechanical properties (in particular the tear strength) of rubber, either vulcanized or thermoplastic. Three alternative methods are specified allowing the use of trouser, angle, or crescent test pieces. In all cases, force is applied to the material in a tensile direction, and a value for tear strength is calculated.
Specimens are prepared from sheets, usually of 2 mm thickness, using a cutting press and die. The profile of the die must match the specimen dimensions identified in the standard for the relevant test piece. In the case of trouser and crescent test pieces, and optionally for angle test pieces, it is also necessary to produce a cut or a nick into the test specimen prior to the start of the test. Additionally, a method for checking the dimensions of the nick, such as an optical microscope, is required. In many cases, it is usual to prepare and test specimens from two different directions in the sheet in order to study the anisotropy of the material.
We suggest performing the test at a standard laboratory temperature since the results obtained are temperature dependent. The specimen thickness is measured close to where tearing is expected to occur, and the specimen is then mounted into the grips of a tensile testing machine, which is usually of single-column or dual-column table-top design. Force is applied at a constant rate of grip separation until the specimen breaks. In the case of crescent and angle test pieces, only the maximum force is required, while for trouser test pieces a record of the forces throughout the tearing process is necessary.
The tear strength, usually expressed in kilonewtons (kN) per meter of thickness, is calculated. A test report is prepared including details of the specimens, the tear strengths obtained for individual specimens, and the median and range of values reported. Testing software, such as Bluehill®, can automatically calculate the desired results and produce a report in accordance with the standard.
Due to the wide range of specimen types and materials included in this standard, we recommend you review the standard thoroughly before determining its suitability for your tests.
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