Meaning
Chemical compounds formed when stabilizer additives in polymers react with heat or oxygen constitute a distinct category of process byproducts. During extrusion and injection moulding, antioxidants degradation products arise as the primary stabilizers like hindered phenols or phosphites scavenge free radicals or decompose peroxides. These byproducts can alter the colour of the resin or reduce its processing stability.
Stabilizer Exhaustion
Stabilizer molecules decompose to protect the polymer chain during heating. The generation of antioxidants degradation products depends directly on melt temperature and residence time in the heating barrel. High shear in the screw increases the concentration of these substances as the polymer flows through narrow gates.
When these molecules accumulate, they can migrate to the surface of the moulded part during cooling, causing cosmetic yellowing or a dusty surface bloom on the finished component.
Mold Deposition
Accumulation of residue on the polished steel of the mould cavity causes plating. This phenomenon occurs when antioxidants degradation products migrate from the hot melt during injection. Regular tool cleaning reduces the impact of these residues but increases cycle costs.
Material Assessment
Recycled resins often carry a higher burden of oxidized additives than virgin materials. Analysing antioxidants degradation products assists in determining if further restabilization is necessary to maintain performance.
