Overview
ISO 1209-2:2007 specifies a standardized laboratory method to determine the flexural strength and the apparent flexural modulus of elasticity of rigid cellular plastics using a three‑point bending arrangement. The standard describes the test principle, required apparatus, specimen preparation and conditioning, the test procedure, calculation of results, precision data and the mandatory contents of a test report. Keywords: ISO 1209-2:2007, rigid cellular plastics, flexural strength, apparent flexural modulus, three‑point bending, materials testing.
Key topics and technical requirements
- Test principle: A centrally applied load is imposed on a rectangular specimen supported at two parallel cylindrical edges; force–deformation is recorded and used to derive flexural strength and modulus.
- Apparatus: Universal testing machine with simultaneous force and deflection recording and load measurement accuracy of ±1%. Support and loading edges are cylindrical with an edge radius of (15 ± 1) mm; span is adjustable (200–450 mm) with a recommended span of 300 mm.
- Specimen geometry: Specimens are rectangular parallelepipeds. The standard prescribes relationships between specimen thickness, width and span (span generally selected in relation to specimen thickness). Specimens must be cut without deforming the cell structure; skins/facings, if present, must be recorded.
- Number of specimens: At least five specimens per sample. For anisotropic materials and single‑skin samples, duplicate sets (different orientations or skin in tension/compression) are required and reported separately.
- Conditioning and test environment: Condition specimens for a minimum of 6 hours under the chosen test conditions. Normal conditions cited include (23 ± 2) °C, (50 ± 10) % RH; the standard also lists alternative temperatures for end‑use simulation.
- Test procedure and speeds: Load applied at a constant head movement. Recommended speeds include (20 ± 1) mm/min for modulus determination and either (20 ± 1) mm/min or (100 ± 10) mm/min for other flexural properties. Tests are normally not continued beyond 5% flexural strain.
- Results: The standard gives formulae for calculating flexural strength and apparent flexural modulus from the recorded force‑deflection curve and specifies reporting and precision requirements.
Applications and users
ISO 1209-2:2007 is used for:
- Quality control and acceptance testing of rigid cellular plastics (e.g., insulation panels, foam structural components).
- Material specification, comparison and R&D for foam manufacturers and converters.
- Certification and performance verification by independent test laboratories.
Primary users: materials engineers, product developers, QA managers, independent testing laboratories and standards/specification writers.
Related standards
- ISO 1209-1 (Basic bending test) - part of the same series on flexural properties.
- ISO 1923 - for determination of linear dimensions of cellular plastics (referenced for specimen measurement).
- ISO 5725 - referenced historically for precision assessment (see standard for current precision guidance).
For full equations, detailed specimen dimensions and mandatory reporting items, consult the official ISO 1209-2:2007 document.
Open preview (PDF)Rigid cellular plastics — Determination of flexural properties — Part 2: Determination of flexural strength and apparent flexural modulus of elasticity