Liquid Silicone Rubber (LSR) is often utilized for seals, valves and diaphragms due to its high elongation (between 400 and 700% at room temperature) and tensile strength over a wide temperature range

. The tensile properties of thermoset rubbers and thermoplastic elastomers need to be measured/tested in order to verify that the quality control standards are met as well as to determine whether or not the material is fit for its purpose. The test should be performed according to ASTM D412 which describes two test methods: A and B.
Method A is the most common testing approach. This method uses a dumbbell shaped specimen (see illustration below) and can be performed on a universal testing machine with standard clamps (tensile testing machine). Method B uses a ring specimen which requires special clamping equipment. Test data is recorded at 100% and 300% modulus values for tension set and set after break, peak and break load as well as elongation. Due to the extensibility, extensometers are also used to accurately measure the elongation or stretch of a sample.

[1] ASTM D 412: Standard Test Methods for Vulcanized Rubber and Thermoplastic Elastomers - Tension; ASTM International, 2008
[2] Campo, E.A.: Industrial Polymers; Hanser Gardner Publications, Cincinnati, 2007
At SIMTEC Silicone Parts, a leading company in manufacturing high precision parts and components, we are exclusively focused and specialized in the production of LSR and LSR/Thermoplastic (Two-Shot) components.

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