Foam and Rubber Testing

Tensile Properties (ASTM D412) and Durometer A Hardness (ASTM D2240) provide a good baseline measurement of the properties of a rubber. These two properties are the most common baseline measurements made on rubber samples. Durometer A Hardness (ASTM D2240) is also known as Shore hardness. Small samples cannot be measured using standard methods but micro-hardness measurements can be performed, such as Durometer M (ASTM D2240) or IRHD Hardness (ASTM D1415).

Various mechanical properties are of significant importance to the performance of foam materials. Such as Compression Set, Compressive Strength, Compression Deflection, Water Absorption, Indentation Force Deflection, Tensile Strength, Elongation, Tear Resistance, etc.

FTIR Analysis (ASTM E1252) can identify the major organic component and EDS Analysis identifies the major inorganic component of a foam or rubber. Basic identification using these two methods is often enough to tell if there is a major difference between two samples and requires only one gram of material. Unfortunately, many foams and rubbers contain a mixture of compounds so it can be very expensive to go beyond a basic identification and identify all of the ingredients. Industry standard is to specify the major material type along with several performance requirements which allows suppliers to improve formulations as long as the performance requirements are still met. Most suppliers consider their formulation to be a trade secret and will only release performance properties for their proprietary formulas.

Material specifications list specific performance requirements for different grades of rubber and foam. Material specifications differ from test methods because test methods only specify how to test for a property but do not include acceptable ranges for the test results. ASTM D2000 and SAE J200 are two of the most common material specifications for rubber. Both specifications must be followed by a string of numbers and letters known as a “line call out” which contains the actual test requirements.