Fluoroelastomer Specialists
The rubber materials selected by designers and technical buyers should meet all their application requirements. The inherent physical characteristics of elastomers can be modified through compounding. However, the knowledge of rubber’s physical properties and their measurement is critical for compound selection.
The following are the physical properties of rubber:
- Specific gravity
- Abrasion resistance
- Tear resistance
- Compression set
- Resilience
- Elongation
- Tensile modulus
- Tensile strength
- Hardness
- The article explains these properties of rubber in detail.
Hardness
The chemical structure of the elastomers provides them with an inherent hardness that can be altered. The modified hardness is then measured in terms of of durometer (duro) on a Shore scale. Shore A is used for a soft to medium-hard rubber. Solid rubber, with a consistency of pencil erasers, has a hardness of 40 duro. By contrast, harder rubber, like that used in hockey pucks, has 90 duro hardness. Figure 1 shows rubber with different hardness.
Tensile Strength
Tensile strength is the amount of force needed to tear apart a rubber specimen until it breaks. It is also known as ultimate tensile strength, and is measured in terms of megapascals or pounds per square inch (psi) according to ASTM D412. The tensile strength is a key factor for designers and buyers as it signifies the point of failure resulting from the stretching of rubber.
Tensile Modulus
Tensile modulus is the stress or force required for producing a strain or an elongation percentage in a rubber sample. Although it sounds similar to tensile strength, the properties are different. Harder rubber usually has a higher tensile modulus, making it more resilient. It is also more resistant to extrusion, which is a process for manufacturing stock materials used in custom fabrication.
Read more: Physical Properties of Rubber – a Buyer and Designer’s Guide
