ISO 178 – Determination of Flexural Properties of Plastics

ISO 178 specifies a method for determining the flexural properties of rigid and semi-rigid plastics under defined conditions.

A preferred test specimen is defined, but parameters are included for alternative specimen sizes for use where appropriate. A range of test speeds is included.

The method is used to investigate the flexural behaviour of the test specimens and to determine the flexural strength, flexural modulus and other aspects of the

flexural stress/strain relationship under the conditions defined.

It applies to a freely supported beam, loaded at midspan (three-point loading test).

The method is suitable for use with the following range of materials:

Thermoplastic moulding, extrusion and casting materials, including filled and reinforced compounds in addition to unfilled types; rigid thermoplastics sheets;

Thermosetting moulding materials, including filled and reinforced compounds; thermosetting sheets.

The method is not suitable for the determination of design parameters but can be used in materials testing and as a quality control test.

*** Before conducting ISO 178 ,  it is important to read the entire specification. Standards can be obtained from appropriate standard authorities.