High Temperature Non Aqueous Volatile Acid Titration in Recycled Polyethylene
High temperature non-aqueous titration strips volatile carboxylic acids from hot PE melt into organic media to quantify corrosion risks and thermal stability.
Peroxide Interference
Meaning
Inhibiting the predictable behavior of additives and resins occurs when residual cross-linking agents trigger unintended chemical interactions. Peroxide interference is a common issue in the production of cross-linked polyethylene where unreacted peroxide molecules can consume antioxidants or pigments.
Reaction Mechanism
Free radicals generated by the decomposition of peroxides attack the molecular structure of stabilizers intended to protect the polymer from UV light or heat. This type of peroxide interference leads to a premature loss of physical properties and can cause unexpected color shifts in the final part.
Masterbatch formulations are
sensitive to oxidation because many organic dyes react poorly with oxygen species. When peroxide interference occurs, the resulting part may show spotting or a faded appearance that does not match the original specification.
Secondary Effect
Uncontrolled reactions during the melt phase can lead to localized gel formation or an unintended increase in viscosity. Managing peroxide interference requires precise control over the loading levels and the half-life of the initiator relative to the residence time in the extruder. Monitoring the torque on the screw provides a real time indication of how these internal reactions are progressing.
These observations allow for adjustments to the cooling rate or screw speed to neutralize the reactive residues.