Evaluating Degradation Mechanisms in Post-Consumer Polyolefin Flake
Polyolefin degradation evaluation requires coupling multi-load melt flow testing and OIT analysis to quantify chain scission and restabilize flake lots.
Restabilization Additive Formulation
Meaning
A customized package of stabilizers is added to recycled or degraded polymers during compounding to replenish depleted additives and prevent thermal oxidation. This formulation, referred to as restabilization additive formulation, combines primary and secondary antioxidants with acid scavengers to ensure processing stability and extend part lifetime. It restores the performance of regrind to levels comparable to virgin resins.
Additive Composition
The additive package contains a blend of sterically hindered phenols for long-term thermal stability and phosphite compounds for melt processing protection. Acid scavengers are also included to neutralize any catalyst residues or acidic degradation products. The ratio of these components must be optimized based on the specific degradation state of the incoming recycled resin.
This optimization ensures that both immediate processing and long-term service life requirements are satisfied.
Compound Stabilization
During compounding of post-consumer flake, the restabilization formulation is added directly to the melt stream. The secondary antioxidants decompose hydroperoxides formed during the collection and sorting phases of the recycling loop. This decomposition prevents the rapid onset of auto-catalytic oxidation during the high temperatures of the extrusion process.
Economic Advantage
Utilizing restabilized regrind allows moulders to increase the percentage of recycled content in their products without sacrificing mechanical performance or part appearance. This ability reduces the consumption of expensive virgin resins and lowers the carbon footprint of the manufacturing run. Restabilization acts as a practical method to maintain profitability in high-volume injection moulding.