1. Tensile properties
Tensile properties are properties that should be considered first for all compounds, including tensile strength, tensile stress, elongation, elongation at break, and permanent set at break, as well as stress-strain curves. Tensile strength is the maximum tensile stress at which a specimen is stretched to break. The constant elongation stress (modulus at constant elongation) is the stress (modulus) attained at a specified elongation. Elongation is the deformation of the specimen caused by tensile stress, expressed as a percentage of the ratio of the elongation increment to the original length. The elongation at break is the elongation of the specimen at break. The tear set is the residual deformation of the gauge length portion after tensile fracture.

2. Hardness
Indicates the ability of rubber to resist external pressure, and is also the basic performance of all rubber compounds. The hardness of rubber is related to some other properties to some extent. For example, the higher the hardness of the rubber compound, the higher the strength, the lower the elongation, the better the wear resistance, and the poorer the low temperature resistance. High hardness rubber can resist extrusion damage under high pressure. Therefore, the appropriate hardness should be selected according to the working characteristics of the parts. At present, Shore A (HS A) type hardness tester is generally used in China to measure the hardness of rubber, which is close to the international rubber hardness value.

3. Compression performance
Compression Properties Rubber seals are normally in compression. Due to the viscoelasticity of rubber, after the rubber is compressed, the compressive stress will decrease with time, which is manifested as compressive stress relaxation; after the pressure is removed, the original shape cannot be restored, which is manifested as compression permanent deformation. In the high temperature oil medium, these phenomena are more significant. They will affect the sealing performance of the seal and are one of the important properties of the rubber compound for the seal.