Melt Shear History and Contaminant Catalyzed Scission in Post Consumer Polyolefin Silo Blends
Deactivate metal catalysts and neutralize acid traces with targeted additives to stabilize viscosity drift and optimize landed cost per good recycled part.
Metal Deactivators
Meaning
Specialty additives chelate metal ions to prevent them from catalyzing the thermal oxidation of polymers during processing and service. Incorporating metal deactivators into a resin compound protects the polymer from the harmful effects of transition metals like copper and iron. These additives are essential for plastic products that are in contact with metal parts or wire conductors.
They prevent the plastic from turning brittle and cracking over time.
Reaction Mechanism
Metal ions act as catalysts by lowering the activation energy of hydroperoxide decomposition. When metal deactivators are mixed into the polymer, they form stable coordination complexes with these ions.
Part Longevity
Molded parts used in automotive and electrical applications must survive harsh environments without losing their mechanical integrity. By using metal deactivators, manufacturers can extend the useful life of polyolefin wire insulation and under-hood components. These additives prevent the copper wire from degrading the surrounding plastic.
This protection is necessary to avoid electrical failures in vehicles and industrial machinery. Without these additives, the polymer sheathing would fail within a fraction of its intended lifespan.
Compounding Practice
Sourcing and mixing additives correctly is a key part of the compounder’s responsibility to ensure resin performance. To formulate effective compounds, metal deactivators are added alongside primary and secondary antioxidants during the extrusion step. This combination provides a synergistic effect that protects the resin during both high-temperature processing and long-term use.
The concentration of the deactivator must be carefully controlled to prevent migration to the surface. Accurate dosing ensures that the additives remain evenly distributed throughout the polymer matrix.