Dicumyl peroxide thermal decomposition

Elastomers must be crosslinked to hold their final form. The crosslinking reaction takes place through generation of free radicals that promote bonding at sites of unsaturation. The most common crosslinking agents for this include reactive peroxides, such as dicumyl peroxide, diacetyl peroxide, di-tert butyl peroxide, and others. Since each has a different temperature at which thermal decomposition initiates, curing conditions vary with the peroxide type. 

Many organic peroxides can be employed, one of the more widely used ones being dicumyl peroxide. Dicumyl peroxide decomposes either thermally to yield free radicals or in acid media by an ionic cleavage mechanism without the production of free radicals. Since the free-radical mechanism is required for the polymer vulcanization reaction, the ionic cleavage decomposition has to be suppressed by the use of a non-acidic medium. The factor determines what type of filler can be used. 

The thermal decomposition of dicumyl peroxide in rubbers has been the subject of numerous studies these are beyond the scope of this review, since they have not been carried out in solution. A few references are included here to provide the reader access to some of the excellent kinetic data available in this area [64 Loa 1,68 Lai 1]. 

The effect of antioxidant on the reaction mechanism of chemical crosslinking of PE with dicumyl peroxide at high temperatures was investigated by ESR. The antioxidant reacted with the alkyl radicals in PE formed by the thermal decomposition of dicumyl peroxide above 120C and disturbed the crosslinking. 10 refs. 

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