Secondary vulcanization is also called post-vulcanization or two-stage vulcanization, which refers to the process in which rubber products reach a certain degree of vulcanization, and the heat source is removed to continue heating and vulcanization.
In a broad sense, a rubber product is vulcanized to a certain extent, even if it is not heated, it can still continue to deepen the vulcanization process under the action of waste heat, or during the storage process of the product, or continue to cross-link under dynamic action. Of course, it also includes the processing technology of continuous heating for secondary vulcanization; the purpose of secondary vulcanization is to further crosslink rubber products, improve the mechanical properties and compression set properties of rubber products, etc. The method of secondary vulcanization is oven hot air vulcanization or vulcanization Tank hot air post vulcanization.
At present, many rubber seals or rubber product production units use secondary vulcanization technology to make rubber seal products, and the technology is constantly updated and optimized with the changes of the times.
The role of silica gel secondary vulcanization:
When the silicone rubber is vulcanized by peroxide, after the decomposition of the peroxide triggers the polymer reaction, low molecular compounds (such as benzene and benzoic acid) are formed in the rubber, which will affect the mechanical properties of the rubber. Moreover, after the silicone rubber is heated and formed in the first stage, its cross-linking density is not enough, and further vulcanization reaction can increase the density, tensile strength, resilience, hardness, swelling degree, density, and thermal stability of the silicone rubber. Vulcanization has greatly improved. If the secondary vulcanization is not carried out, the performance of the produced silica gel may be affected to a certain extent, and a product with better performance cannot be obtained.

Room termperature curing polysilazane, pls check IOTA 9150, IOTA 9150A. 
High termperature curing polysilazane, pls check IOTA 9108, IOTA 9118.