Influence of Metals, Fillers and Pigments on Stablity

Abstract

Metal ions catalyze the decomposition of peroxides forming reactive radicals and thus contribute to accelerated autoxidation (Eqs. 1.16 and 1.17). Deactivation of this process by suitable metal ion deactivators was proposed long ago by Downing and co-workers [224]. Hansen and co-workers [225] have shown the significant effect of copper on degradation of polypropylene and Hawkins and co-workers [226] arrived at similar results for polyethylene in contact with copper. Allara and Chan [227] were able to demonstrate that the oxidation state of the metal ion plays an important role in the degradation of polyethylene. Allara and co-workers [228, 229] have also shown that the catalytic reaction occurs at the interface between copper and the polyolefin. Later on, Sack and co-workers [230] and Wagner ~nd co-workers [231]found that the catalytic effect of copper ions also extends further into the polymer. Therefore, it can be assumed that in addition to heterogeneousreactions at the polymer/metal interface, there are also homogeneous reactions of migrating copper ions inside the polymer itself.