physical property:
1. Before vulcanization (curing), it is a "solid". The color depends on the color material added during mixing. If it is not added, it is white. The plasticity value is about 200~300
2. After vulcanization, the transparency of the colorless rubber is not as good as that of the liquid rubber, and the "light transmittance" is not higher than 70%. The "rebound value" of the compound with the same "hardness" is generally lower than that of the liquid rubber, but the "mechanical property" is generally higher than that of the liquid rubber. The "tensile strength" reaches 10~20MPa, the "tear resistance" reaches 40~60KN/m, and the "elongation" is generally better than that of the liquid rubber with the same hardness. The "curing temperature" is generally 140~180 ℃. “
Chemical properties/properties:
Raw rubber mixture is a mixture of siloxanes. Its molecule belongs to the chain helix structure, and its average molecular weight is about 400000-800000 mPa S, its viscosity is directly related to its molecular weight. The molecular weight can be measured with Ubbelohde viscometer, which is called viscosity average molecular weight. As for the reinforcement mechanism of the filler, the filler nanometer SiO2 powder (precipitation SiO2 powder) is evenly distributed in the raw rubber to form a crystal like structure. The hydroxyl group on the surface of the SiO2 particle forms a hydrogen bond with the Si-O bond of the raw rubber. Each SiO2 particle, as a core, extends hydrogen bonds in all directions to connect with the molecular chain of the raw rubber. Countless such structures, together with other additives, form a high viscosity and high performance rubber blend.
Silicone rubber has excellent heat resistance, cold resistance, dielectric property, ozone resistance, atmospheric aging resistance and other properties. The outstanding performance of silicone rubber is that it can be used at a wide range of temperatures from - 60 ℃ (or lower temperature) to+250 ℃ (or higher temperature) for a long time. As for which property (quality) is superior, it is determined by the type of raw rubber, filler and auxiliary agent used.
For silicone rubber, please check the details:
https://www.siliconerubbers.net/product-general-purpose-grade-htv-silicone-rubber.html 
