ISO 34-1 - Rubber, Vulcanized or Thermoplastic – Determination of Tear Strength

ISO 34-1 is used to investigate the tear strength of either vulcanized or thermoplastic rubber. Three alternative methods are specified in the standard for specimen shape: trouser, angle, and crescent. In all cases, force is applied to the material in a tensile direction and a value for tear strength is calculated.

Specimens are usually prepared with a cutting press and die from 2 mm thick sheets. 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, it is 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 that testing is performed at standard laboratory temperature as results obtained are temperature dependent. Specimen thickness should be measured close to where tearing is expected to occur. 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 trouser test pieces require that force is recorded throughout the tearing process as an average value.

The challenges of testing to this standard:

• Specimen slipping
• Reporting calculations in compliance with standard

Our solutions:

• Specimen slippage - Depending on the size of the specimen, we suggest two options for testing specimens under ISO 34-1:
  • Self-tightening roller grips - These are an optimal solution for rubber material. Grip capacity is available in 1kN, 2kN, and 5kN. Specimen insertion and removal is simple and fast.
  • Side-acting pneumatic grips - Constant air pressure, along with patented quick-change rubber, serrated, or flat grip faces will ensure specimens do not slip under test.
• Reporting calculations in compliance with the standard - Bluehill^® Universal testing software has advanced pre-built methods available with preconfigured plastic specific calculations helping to ensure compliance. Using features, such as an appropriate preload, is critical for achieving accurate, repeatable results. A preload eliminates the compressive forces on a specimen that often occur when initially placed into grips.

Due to the wide range of specimen types and materials included in this standard, it is recommended that this testing standard is reviewed thoroughly before determining its suitability for your tests.