Hindered Phenol + Phosphite Composite Antioxidant AO-Blend

Thermal oxidative degradation of polymers proceeds in two stages: (1) Initiation/propagation—peroxy radicals abstract hydrogen from polymer chains (primary AO, hindered phenols, interrupt this by donating H to radicals); (2) Hydroperoxide decomposition—unstable hydroperoxides decompose into chain-breaking alkoxy radicals (secondary AO, phosphites, reduce hydroperoxides to alcohols before decomposition). Using both provides synergistic protection exceeding either alone at the same total dosage. The standard combination is Irganox 1010-type (hindered phenol) + Irgafos 168-type (phosphite) at 1:1 or 1:2 ratio, well-established across plastics and coatings industries.