What are the mechanical properties of plastics?

The mechanical properties of plastic affect how it responds to different types of loads and conditions. Tensile strength at yield and elongation at break are two commonly used indicators of material properties. But choosing a material for your product goes beyond that, as deformation is not the result you want.

Material data sheets are the starting point for selecting the appropriate plastic - they should not be used to determine your polymer or product design. These tables are provided by polymer suppliers and describe the properties of a particular material grade. However, relying solely on datasheets may not give you the results you expect. Performance results are based on accepted industry standard testing conducted under specific conditions (e.g. temperature, humidity, machine, speed, preconditioning) which may vary significantly from those your product will experience. You also have to consider material compatibility and how they will react with other materials used. For example, certain adhesives may cause some plastics to become brittle. There may also be some regulations that should be considered for materials acceptable for food or medical devices.

Knowing that choosing a plastic is more important than looking at a datasheet, we'll look at some of the mechanical properties that can be found on it. While there is no standard for data sheets, tensile strength, elastic modulus, and elongation are important mechanical properties to consider when designing a product.