Influence of Metallic Contaminations

In addition to the factors mentioned, such as temperature, oxygen content, and mechanicai ioad, other factors also play a large role, such as the presence of chromophores and metal ions. The catalytic effect of metal ions, e.g., created by wear in the processing machines, alone or in the presence of water, can be considerable. The effect of metals can be eliminated by complexing agents. On the other hand, appropriately protected processing equipment should be used with abrasive polymer grades [599] (s. Section 1.4.2.1.2). 

Accelerated polypropylene aging in a convection oven caused by the presence of clearly recognizable metallic contamination (caused during processing) in the center of the PP pest  

---

Kivevele, T., Huan, Z.J., 2015. Influence of metal contaminants and antioxidant additives on storage stability of biodiesel produced from non-edible oils of Eastern Africa origin Croton megalocarpus and Moringa oleifera oils). Fuel 158, 530—537. 

---