First, the viscosity. Technical terminology: The volumetric property of a liquid, pseudo-liquid or pseudo-solid material against flow, that is, the internal friction or internal flow resistance exhibited by molecules when flowing by an external force. Usually the viscosity is proportional to the hardness.
Second, the hardness. The ability of a material to partially resist the pressing of a hard object into its surface is called hardness. Silicone rubber has a Shore hardness range of 10 to 80, which gives the designer the freedom to choose the hardness required to best achieve a particular function. Various intermediate hardness values can be achieved by mixing the polymer substrates, fillers, and auxiliaries in different ratios. Similarly, the time and temperature of heat curing can also change the hardness without damaging other physical characteristics.
Third, the tensile strength. Tensile strength is the force required to cause each range of units when a piece of rubber material is torn. The hot vulcanized solid silicone rubber has a tensile strength ranging from 4.0 to 12.5 MPa. The tensile strength of fluorosilicone rubber ranges from 8.7 to 12.1 MPa. The tensile strength of the liquid silicone rubber ranges from 3.6 to 11.0 MPa.
Fourth, the tear strength. Resistance to enlargement of the incision or score when force is applied to the sample with the incision. The hot-sulphurized solid silicone rubber can be not torn even after being cut and placed under extremely high torsional stress. The hot vulcanized solid silicone rubber has a tear strength ranging from 9 to 55 kN/m. The fluorosilicone tear strength range is between 17.5 and 46.4 kN/m. Liquid silicone rubber tear strength ranges from 11.5 to 52 kN/m.