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Definition of shape and dimensions of specimen to be used as per ISO

Specimen shapes for tests on molding materials

The overriding objective when testing molding materials is a high degree of reproducibility. This requires restricting the number of specimen types.

Specimens are usually produced by injection molding. Type 1A specimens as defined in ISO 527-2 are used; in ISO 3167 these are designated Specimen Type A and are additionally restricted to a specified thickness of 4mm. These specimens are also designated Type A1 in ISO 20753.

Specimen shapes for tensile test plastic molding materials

Injection-molded specimens display decreasing orientation as the distance from the feed-point increases, leading to non-constant mechanical-property curves along the length of the specimen and therefore frequently resulting in specimen break on the side remote from the gate.

The preferred gage-length for the specimen is 75mm, or alternatively 50mm.

As an alternative the use of specimens of Type 1B is permitted; these are designated Type B in ISO 3167 and Type A2 in ISO 20753.

These specimens are generally machined from pressed or injection-molded sheets; the orientations of the polymer normally differ significantly from those in injection-molded specimens. Comparability of results obtained using different specimen shapes is not guaranteed.

A gage length of 50mm is specified for Type 1B specimens due to the larger radius resulting in a shorter parallel area.

Specimens taken from components or semi-finished products

There is often insufficient room on components or semi-finished products to remove the preferred Type 1B specimens. ISO 527-2 therefore offers various reduced-size versions of this specimen with shapes 1BA and 1BB. Specimen shapes 5A and 5B are identical in shape and size to Shapes 2 and 3 of ISO 37 (tensile test on rubber).

To achieve good comparability of results, specimens are removed from the semi-finished product at exactly defined positions and alignments.

Specimen shapes for tensile test ISO 527-2 on thermoplastics and thermoset plastics

Aging tests, media aging test, weathering test

A small cross-section is advantageous for all aging procedures which progress from the surface of the specimen. Often only the maximum tensile stress is used for assessment of this behavior. The use of extensometers is accordingly not necessary and thin, waisted specimens can be used. ISO 527 offers Types CP and CW for this purpose; these are borrowed from impact tensile standard ISO 8256.

Specimen shape aging test to ISO 527 Types CP and CW

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