Condensed silicone and additive silicone are two different types of silicone rubber, which have some differences in chemical structure and properties.

The following are their main differences:
Chemical structure:
Condensed silica gel: Condensed silica gel is a silicone rubber with three-dimensional network structure formed by silicon oxygen chain (Si-O-Si) through Condensation reaction. In the preparation process, siloxane monomers containing hydroxyl (OH) and alcohol group (OR) functional groups are usually used, such as silane and silanols. In the Condensation reaction, hydroxyl and alcohol groups will combine with oxygen atoms to release water molecules and form a cross-linked structure.

Addition silica gel: addition silica gel is a silicone rubber that is formed by the silicon carbon chain (Si-C) through Addition reaction to form a three-dimensional cross-linking network. It is usually obtained by copolymerization reaction between organosilicon monomers containing double bond (C=C) functional groups and siloxane monomers. In the Addition reaction, the double bond will be added with the silicon oxygen bond (Si-O) in the siloxane monomer to form the silicon carbon bond (Si-C), so as to build the silicon carbon chain.

Hardness and elasticity:
Condensed silicone: Condensed silicone typically has higher hardness and lower elasticity. This makes it an excellent sealing and insulating material in many applications.
Additive silicone: Additive silicone has lower hardness and higher elasticity. It is used as a soft elastic material in many applications, suitable for manufacturing sealing rings, elastic parts, medical supplies, etc.

Thermal stability:
Condensed silica gel: Due to its structure of silicon oxygen bonds, condensed silica gel usually has good high-temperature resistance and can be used stably for a long time in high-temperature environments.
Additive silicone: The high-temperature resistance of additive silicone is usually not as good as that of condensed silicone, but its elasticity performance is better at low temperatures.

Compression deformation:
Condensed silica gel: Condensed silica gel usually has small compression deformation, which means it rebounds quickly after being subjected to a certain pressure.

Additive silicone: Additive silicone typically has significant compression deformation, which means that it rebounds slowly after being subjected to a certain amount of pressure.

According to different application requirements, manufacturers can choose condensation type silicone or addition type silicone to meet the performance requirements of specific products.