1.1 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. 1.2 The method is used to investigate the flexural behaviour [1] 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). 1.3 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 <=7,5 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 [3, 4] . NOTE For certain types of textile-fibre-reinforced plastics, a four-point bending test is preferred. It is described in reference [2]. 1.4 The method is performed using specimens which may be moulded to the specified dimensions, machined from the central portion of a standard multipurpose test specimen (see ISO 3167) or machined from finished or semi-finished products such as mouldings, or extruded or cast sheet.