Meaning
A hydrolytically stable phosphite secondary antioxidant protects polymers from thermal degradation during the melt processing stage. Processing at high temperatures causes ao-168 to react with hydroperoxides, which stops the chain reaction of polymer breakdown before it can damage the physical properties of the resin. This additive works during the extrusion and injection phases to maintain the original melt flow rate and color of the material.
Secondary Protection
While primary antioxidants provide long term stability, ao-168 focuses on the heat history of the material during manufacturing. It prevents the rapid increase in viscosity or the thinning of the melt that occurs when a polymer is subjected to multiple heat cycles. Stabilizing the melt allows for more consistent part weights and reduced scrap rates in high volume production.
Hydrolytic Stability
Resistance to moisture ensures that the additive remains effective even after exposure to humid storage conditions. Some phosphites decompose into acidic byproducts when they encounter water, but ao-168 maintains its chemical integrity. Stable behavior prevents plate-out on the mould surface and avoids the formation of black specks in the finished product.
Processing Efficiency
Molders benefit from the use of this stabilizer when running high speed equipment or using complex hot runner systems. Presence of ao-168 ensures that the polymer does not crosslink or degrade in the barrel during unplanned machine stoppages. Because it protects the resin so effectively, the resulting parts exhibit better surface finish and more reliable mechanical performance over their entire lifespan.
Every pound of resin processed with this stabilizer retains a higher percentage of its original molecular weight, which is necessary for maintaining the impact strength of thin walled containers.
