How is the cell structure of open-cell rubber and closed-cell rubber formed?

Due to the differences between the cell structure of open-cell rubber and closed-cell rubber, the basic properties and the application occasion of rubber compound will be also different. So actually how is the cell structure of open-cell and closed-cell rubber formed y during the production process? What are the factors related to the pore structure of foamed? How shall we choose the suitable ingredient in open-cell rubber and closed-cell rubber? Today I will tell you about the selection skills of the ingredient during the production process of open-cell and closed-cell rubber.

1. Effect of vulcanization system on cell structure
Under normal circumstances, the vulcanization process and foaming process of the rubber compound are carried out at the same time on the condition that the vulcanization rate and the foaming speed must be matched perfectly, otherwise it will directly affect the cell structure and even lead to foaming failure. Therefore, when designing the vulcanization system of sponge foam rubber, the vulcanization speed must be matched with the foaming speed (The foaming speed is difficult to adjust). Generally speaking, the delayed accelerator and the vulcanization accelerator that starts quickly should be combined together when using the sulfur vulcanization system ; the peroxide vulcanization system itself has a fast vulcanization start and a slow vulcanization speed, so it is more suitable for the production of sponge foam rubber.

2. Effect of foaming agent on cell structure

Foaming agent is a substance that can make the rubber compound form cells in the formula of sponge foam rubber products. There are many types of foaming agents. The cell structures of the compound are different because of different types of foaming agents and compound agents. The foaming agent AC among organic foaming agent has a slower foaming speed, a slightly higher decomposition temperature, and a small permeability of the decomposed gas, so it is suitable for the production of closed-cell rubber products. Relatively speaking, the thermal decomposition of the inorganic foaming agent (sodium bicarbonate) will generate a large amount of ammonia gas, carbon dioxide, and water vapor. These gases have greater permeability in the rubber compound, and are generally used in open-cell rubber with large cell pores.

The gas permeability formed in the rubber material will affect the cell structure of the sponge foam rubber when the blowing agent reacts . So the rubber product manufacturers should select the appropriate type of blowing agent according to the actual needs.
Two important factors that affect the cellular structure of foamed rubber are the vulcanization system and the foaming system. Also, fillers, softeners, and anti-aging agents in the formulation of rubber products affect the cellular structure of the rubber compound. Generally speaking, the compounding agent similar to vulcanized ointment can improve the stiffness of rubber compound and suit the preparation of open-cell rubber.