Hello and welcome to a new blog post in which we discuss the influence of fillers on the efficiency of Antioxidans additives in Polypropylene (PP).
Fillers and Antioxidant Efficiency in Polypropylene
The Figure 1 highlights an important point about the long-term thermo-oxidative stability of polypropylene (PP): not all fillers are neutral in their effect on ageing performance.
Under oven ageing at 160°C, the results show a clear reduction in time to embrittlement for PP filled with talc and calcium carbonate (CaCO₃) compared with unfilled PP.
In other words, both fillers have a negative impact on long-term stability under these conditions, with talc showing the strongest reduction. The figure is a useful reminder that filler selection must be considered not only from a cost and stiffness perspective, but also from the standpoint of antioxidant efficiency and durability.
A note on testing for plastics embrittlement
The standards ASTM D5510 (Standard Practice for Heat Aging of Oxidatively Degradable Plastics) and ASTM D3045 (Standard Practice for Heat Aging of Plastics Without Load) were used with regular tensile testing during oven aging (ISO 527 / ASTM D882). Focus is not so much on tensile strength, but more on Elongation-at-break which is the most direct indicator of embrittlement.
A sharp drop (often to <50% of its original value) indicates the PP has become brittle. A brittle PP might maintain its tensile strength, it will snap almost immediately when bent or stretched.
Check out my other posts on additives here:
Thanks for reading & #findoutaboutplastics!
Greetings,
Herwig
Literature:
[2] M. Bonnet - Kunststoffe in der Ingenieuranwendung
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