Primary Antioxidants H Donors and Radical Interceptors

The effect of primary antioxidants is based on reactions with polymer radicals containing oxygen that are formed during auto-oxidative degradation of plastics. These very reactive radicals are transformed into inactive or less reactive compounds, thus causing the end of radical chain reaction. Fig. 1.13, Section 1.4.2. The antioxidants are consumed during this reaction. 

The major range of applications for primary antioxidants is stabilization for longterm use under thermal load. In part, their reactivity enables them to establish certain process stabilization at elevated processing temperatures. This describes an effect that can be observed during the entire stabilization process at several points different products fulfill the tasks of other stabilizers and are thus in part prevented from fulfilling their actual purpose. For instance, insufficient process stabilization can lead to a considerable reduction of antioxidative long-term stabilization, because the phenolic antioxidants assume the role of process stabilizers and are thereby partially consumed [510]. 

Detailed descriptions of the function of primary antioxidants can be found in [518] and [536]. 

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