Stabilization by Decreasing Initiation Rate

Some polyaromatic compounds [24] may be used in the case of radiochemical ageing to dissipate directly the incident ray energy by some photophysical processes (such as fluorescence). In the case of a hip, there is however no interest to prevent polymer from y ray effect since y-radiations improve the mechanical properties of the polymer. It is preferable to limit the side effect of the radiation induced radicals during the in vivo thermal ageing of polymer. 

Since alkyl radicals lead to hydroperoxides (see 3.2.1. Mechanism of oxidation [18]) being the main source of radicals during thermal oxidation [18], it can be first tried to decrease POOH concentration by reducing them into stable products using hydroperoxides reducers such as  

The sulfur yields to a sulfate, which could possibly have a further stabilizing role by successive reactions with POOH [29]  

Since hydroperoxide decomposition is catalyzed by metallic ions [30]  

Some stabilizers contain therefore a metal-coordinating functionality [31,32]  

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