Originally, rubbers are independent macromolecular chains with poor characteristics and it's essential to incorporate numerous additives into them, currently 10 up to 15, during a mixing process to subsequently promote crosslinking, reinforcement, ageing protection... Sometimes the molecular weight of the elastomer, specially the natural rubber, is so high that too difficult and expensive is the incorporation of additives. The only solution is to masticate the rubber in presence of the oxygen of air by mechanical breaking and oxidative scission of the macromolecular chains. The process is time, energy and money consuming. To speed it, it is possible to use chemical additives or peptizers, which promotes the reduction of the elastomer molecular weight by chemical means thus increasing the efficiency of rubber mastication.
The following figure 'Mechanical-Mastication-versus-Chemical-Peptizing' compares the dump times and temperatures, the energy consumption for the same reduction of the consistency of the same rubber.