Peroxide cure

The amount of peroxide has little influence on the rate of cure but will influence the final crosslink density. This allows the compounder to optimize such properties as:

• rebound resilience
• compression set
• modulus
• elongation at break.

Peroxides give heat-stable crosslinks. A fairly high ratio of ethylene/propylene in the polymer contributes to the crosslinking efficiency. When the free radicals formed by the peroxide attack a propylene unit, there is a much greater tendency to break the chain than to form crosslinks. Therefore more crosslinks per mole of peroxide are formed in an EPDM with high ethylene content than in an EPDM with low ethylene content.

 

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