International Organization for Standardization

Plastics — Determination of flexural properties AMENDMENT 1: Precision statement - Fourth Edition
 N 178 AMD 1

Annotation

This International Standard specifies a method for determining the flexural properties of rigid (see 3.12) and semi-rigid plastics under defined conditions. A standard 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 for determining 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:

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

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

In agreement with ISO 10350-1 and ISO 10350-2, this International Standard applies to fibre-reinforced compounds with fibre lengths  7,3 mm prior to processing. For long-fibre-reinforced materials (laminates) with fibre lengths > 7,5 mm, see reference [2] in the bibliography.

The method is not normally suitable for use with rigid cellular materials and sandwich structures containing cellular material.

NOTE For certain types of textile-fibre-reinforced plastics, a four-point bending test is preferred. It is described in reference [2].