Viscosity
Technical Definition: The volumetric property of a liquid, quasi-liquid, or quasi-solid substance that resists flow; specifically, the internal friction or internal resistance to flow exhibited between molecules when the substance is subjected to external forces. Generally, viscosity is directly proportional to hardness.
Hardness
Hardness is defined as a material's ability to locally resist indentation by a harder object. Silicone rubber possesses a Shore hardness range of 10 to 80, providing designers with ample freedom to select the specific hardness required to optimally fulfill a particular function. By blending polymer bases, fillers, and additives in varying proportions, a wide spectrum of intermediate hardness values can be achieved.
Tensile Strength
Tensile strength refers to the force per unit area required to cause a sample of rubber material to rupture. The tensile strength range for heat-vulcanized solid silicone rubber lies between 4.0 and 12.5 MPa. Fluorosilicone rubber exhibits a tensile strength range of 8.7 to 12.1 MPa, while liquid silicone rubber ranges from 3.6 to 11.0 MPa.
Tear Strength
Tear strength is the resistance offered against the propagation of a cut or notch when force is applied to a notched sample. Even when cut and subjected to extremely high torsional stress, heat-vulcanized solid silicone rubber remains resistant to tearing. The tear strength range for heat-vulcanized solid silicone rubber falls between 9 and 55 kN/m.
Elongation
Typically referring to "ultimate elongation at break," this metric represents the percentage increase in length relative to the original length at the moment the sample fractures. The general elongation range for heat-vulcanized solid silicone rubber is between 90% and 1120%. Fluorosilicone rubber typically exhibits an elongation range of 159% to 699%.
