ASTM D638 tests the tensile properties of plastics. ASTM D638 measures plastics tensile properties including ultimate tensile strength, yield strength, elongation and Poisson’s ratio. The samples are cut in the form of a standard dumbbell shape providing the sample a reduced section where the break will occur upon testing. The samples are tested in specific conditions of pre-treatment, sample orientation, temperature, humidity, and testing machine speed.
ASTM D638 can be used for testing materials up to 14 mm (0.55 in.) in thickness. However, thin sheeting materials, including film less than 1.0 mm (0.04 in.) in thickness, should be tested using the ASTM D882 test. Micom offers ASTM D638 testing services as part of its Plastics and Polymers testing.
ASTM D638 Typical Experimental Parameters
Number of specimens per product: 5. In some cases, the tensile properties need to be measured both in the machine and perpendicular to the machine direction as they can vary substantially from one orientation to the other. This behavior is called anisotropy.
Crosshead speed: Between 5 mm per min and 500 mm per min. It varies as a function of the material’s rigidity, shape and thickness. Typically, the softer the material, the faster it will get pulled. Please refer to table 1 of the test method for specific details or contact our experts for assistance.
Dumbbell type: The dumbbell dimensions are modulated as a function of the material’s thickness. Sample cutting is of paramount importance for obtaining accurate and reproducible results.
Conditioning and testing temperature: Usually 23 ± 2 °C (unless otherwise specified). However, it is not uncommon to test at lower temperatures as plastics get more brittle at colder temperatures. Micom can test at temperatures as low as -78 °C.
Conditioning and testing relative humidity: 50 ± 5%
Other Test Methods Related to ASTM D638 Testing
If you have any questions about ASTM D638 or other plastic and polymer tests, we invite you to contact us today. It will be our pleasure to answer your questions and help you with your custom testing requirements.
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