What is hardness (thermoplastics)?

The hardness describes the resistance of the sample to penetration by a body. The Shore D hardness test is often used for thermoplastics (comparable to Shore A). However, ball indentation hardness is also increasingly being tested. With ball indentation hardness, a ball with a diameter of 5 mm is pressed onto the surface over a certain period of time and the surface of the indentation is determined using the penetration depth. Unlike elastomers, the hardness of thermoplastics is not related to the mechanical properties. It is largely determined by the material type and can only be changed by plasticizers or in the case of thermoplastic elastomers.