Antidumping Duty Lines That Move a Polymer off the Shortlist
Antidumping duties reorder polymer shortlists when cash deposits, scope rulings, and customs reclassifications destroy the landed cost advantage of imported resin.
Oxidative Induction Time ISO 11357-6
Meaning
Standardized testing methods determine the resistance of polymers to oxidative degradation by measuring the time before the onset of oxidation. The protocol defined in Oxidative Induction Time ISO 11357-6 uses differential scanning calorimetry to measure the thermal stability of a material in a heated oxygen atmosphere. This measurement is critical for verifying the performance of antioxidant packages in resins that will be exposed to high temperatures.
Test Procedure
The test specimen is heated inside a calorimeter chamber under an inert nitrogen gas purge to a specified temperature, typically two hundred degrees Celsius. Once the temperature stabilizes, the purge gas is switched from nitrogen to oxygen, and the chamber is held at a constant temperature. The instrument monitors the heat flow from the sample until a sharp exothermic peak occurs.
This peak indicates the onset of polymer oxidation, and the elapsed time between the gas switch and the start of the reaction is recorded as the induction time.
Stabilization Analysis
Longer induction times indicate that the polymer has a robust antioxidant system that can resist thermal oxidation for a longer period. This measurement helps compounders evaluate different antioxidant formulations and determine the optimal dose of stabilizer needed to protect the resin during processing. A short induction time suggests that the resin is susceptible to thermal degradation during extrusion and molding.
Part Lifetime
Heat and shear during the molding process consume antioxidants, which reduces the residual induction time of the molded part. Recycled regrind exhibits significantly lower induction times than virgin resin because of the cumulative degradation from multiple processing steps. Measuring this depletion helps processors monitor the quality of recycled materials and ensure that the finished parts do not degrade prematurely.