Hydroperoxide groups are widely believed to be critical intermediates in the oxidative degradation of many polymers, especially commodity polyolefins [34, 5 1-53]. Trace amounts of hydroperoxides in polyolefins such as polyethylene (PE) may be formed inadvertently during polymerization and processing. It is found that hydroperoxides are formed almost quantitatively from the oxygen absorbed by the polymer during its induction period [26,27,44]. Moreover, it has baeen suggested that the stability of articles made from polyolefins depends largely on the concentration of hydroperoxides formed during storage of the nascent polymer before any stabilizer is added 1701.