EFFECT OF FILLERS ON DEGRADATIVE PROCESSES

However, fillers and additives may also delay degradation processes. The use of CaCOa in weathered filled and unfilled PE-HD illustrates how fillers can influence degradation reactions and thus delay the formation of carbonyl and hydrogen peroxide groups. They can also act as a protective layer against UV light [80], [81]. The effects of fillers and additives on degradation depend on the type of additives and on their pre-treatment [82]. 

If the degradation process is set off by one of these effects, even storage at normal (ambient) temperature leads to a continuation also, processes follow an Arrhenius behavior and are accelerated by higher temperatures. The process may be catalyzed by metal ions present in the polymer (through impurities, fillers etc.) especially critical are copper and iron. Apart from the aforementioned effect on the molar weight distribution (MWD), the phase structure of impact copolymers may also be changed. 

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