Meaning
Materials aging analysis processes monitor the chemical degradation of polymers exposed to elevated temperatures in the presence of oxygen. Quality control laboratories employ thermal oxidative degradation tracking to evaluate the long-term stability of compounded plastic resins during storage and processing. This monitoring is confined to reactions involving molecular oxygen and does not measure degradation caused by purely thermal or mechanical stress.
Analytical Measurement
Carbonyl index measurements are calculated from the infrared spectra of the aged samples to quantify the level of oxidation. The thermal oxidative degradation tracking records the growth of these oxidation products over time to determine the degradation rate of the polymer. This chemical change is correlated with the decline in the mechanical properties of the material, such as elongation at break.
Stabilizer Evaluation
Compounders use this tracking method to evaluate the performance of different antioxidant packages in the polymer formulation. The thermal oxidative degradation tracking allows for the optimization of stabilizer concentrations to meet the specific requirements of the downstream application. This screening helps to identify cost-effective formulations that maintain the required lifetime of the molded part under operating conditions.
Process Control
Extruders must be purged with inert gas or operated at lower temperatures when the tracking results show high susceptibility to oxidation. Thermal oxidative degradation tracking provides the necessary data to establish the maximum safe operating window for the polymer during compounding and molding. This information helps to prevent the production of brittle parts that would fail prematurely in service, ensuring that the processed resin maintains its structural integrity throughout the intended life of the product.
