ASTM Test Standards for Typical Physical Properties
Durometer per ASTM 2240
The ASTM D2240 standard is used to evaluate the hardness of a rubber sample with the use of a series of tests performed with a durometer gauge. Hardness is measured when a force is applied to the sample with an indentor under specific conditions.
Tensile Strength (psi) per ASTM D412
ASTM D412 is the most common standard for determining the tensile properties of vulcanized (thermoset) rubber.
ASTM D412 measures the elasticity of a material while under tensile strain, as well as its behavior after testing when the material is no longer being stressed. ASTM D412 is conducted on a universal testing machine (also called a tensile testing machine) at a rate of 500 ± 50 mm/min until the specimen fails.
Though ASTM D412 measures many different tensile properties, the following are the most common:
- Tensile strength – the maximum tensile stress applied in stretching a specimen to rupture.
- Tensile stress at a given elongation – the stress required to stretch the uniform cross-section of a test specimen to a given elongation.
- Ultimate elongation – the elongation at which rupture occurs in the application of continued tensile stress.
Tear Strength (ppi) per ASTM D624
ASTM D624 is a common test method used to determine the tear strength of vulcanized rubber and thermoplastic elastomers. Due to the specimen shapes often used, this test is sometimes called a trouser, angle, or crescent test.
Compression Set (%) per ASTM D395
ASTM D395 specifies two test methods for testing the compressive properties of rubber. Test Method A governs the compression set under constant force while Test Method B governs the compression set under a constant deflection. Method A uses a spring to push down on the sample and maintain constant force.