Peroxidvulkanisierung

Peroxidvulkanisierung is a chemical process used to crosslink polymers, primarily elastomers, by employing organic peroxides as curing agents. This method is distinct from sulfur vulcanization, which is more common for diene rubbers like natural rubber and styrene-butadiene rubber. Peroxidvulkanisierung is particularly effective for polymers containing saturated carbon-carbon bonds, such as silicone rubber, ethylene-propylene-diene monomer (EPDM) rubber, and fluoroelastomers.

During the process, organic peroxides decompose at elevated temperatures, generating free radicals. These free radicals then abstract hydrogen atoms from the polymer chains, creating polymer radicals. Two such polymer radicals can then combine to form a stable carbon-carbon crosslink, effectively creating a three-dimensional network structure. This network is responsible for the improved mechanical properties of the rubber, including increased tensile strength, elasticity, and resistance to heat and chemicals.

Compared to sulfur vulcanization, peroxidvulkanisierung offers several advantages. It produces crosslinks that are more thermally stable, leading to better heat aging resistance. The crosslinks are also typically more resistant to ozone and certain chemicals. Furthermore, peroxidvulkanisierung does not generate byproducts like sulfur vulcanization, which can sometimes lead to blooming or staining. However, peroxidvulkanisierung can be more expensive and may require higher curing temperatures. It is also less effective for polymers with a high degree of unsaturation.