ISO 11357-6:2025

Overview

ISO 11357-6:2025 - Plastics - Differential scanning calorimetry (DSC) - Part 6 specifies standardized DSC methods for measuring oxidation induction time (isothermal OIT) and oxidation induction temperature (dynamic OIT / OOT) of polymeric materials. The fourth edition updates procedures (including an added isothermal stepwise temperature calibration) and is primarily applicable to polyolefin resins in fully stabilized or compounded forms (raw materials or finished products), with possible application to other plastics.

Key topics and technical requirements

• Principle: Measurement of the time or temperature at which exothermic oxidation begins when a specimen is exposed to oxygen or air using a DSC.
• Test methods:
  • Isothermal OIT: specimen heated under inert gas, held at specified temperature, atmosphere switched to oxygen/air; OIT = time from oxygen introduction to oxidation onset.
  • Dynamic OIT: specimen heated in oxygen/air at a constant rate; OIT/OOT = temperature at oxidation onset.
• Apparatus and materials: requirements for DSC instrument, crucibles, flowmeter, gas supplies (oxygen, air, nitrogen), gas-selector and regulators.
• Specimen preparation: guidance for specimens from compression-moulded plates, injection-moulded plates, melt flow extrudates, or finished parts.
• Calibration and performance:
  • Dynamic temperature calibration and the newly included isothermal stepwise temperature calibration for isothermal OIT.
  • Instrument setup, sensitivity adjustment and recommended gas flows.
• Results and reporting: how to express OIT/OOT results, precision and bias statements, and required information for test reports.
• Limitations and notes: OIT/OOT are relative measures of stabilization - they are indicative of antioxidant effectiveness but do not quantify antioxidant concentration. Results depend on test temperature, heating rate, specimen surface area and atmosphere (pure oxygen vs air).

Applications and users

ISO 11357-6:2025 is used for:

• Quality control of polyolefin resins and compounded plastics to verify oxidative stability.
• Formulation development and comparative screening of antioxidant packages in R&D labs.
• Incoming raw-material inspection by converters and compounders.
• Acceptance testing for finished products where thermal-oxidative resistance is relevant. Primary users include polymer manufacturers, compounders, testing laboratories, regulatory bodies and material specification engineers.

Related standards

• ISO 11357-1 (DSC - General principles)
• ISO 472 (Plastics - Vocabulary)
• Material-specific standards (e.g., ISO 17855-2, ISO 19069-2, ISO 21302-2) referenced for specimen preparation and property determination.

ISO 11357-6:2025 provides a reproducible DSC-based framework for assessing oxidation resistance, making it a practical tool for ensuring polymer performance and stability in manufacturing and product development.