ISO 11358-2:2021 PDF

Overview

ISO 11358-2:2021 - "Plastics - Thermogravimetry (TG) of polymers - Part 2: Determination of activation energy" specifies a standardized thermogravimetric (TG) method to determine the activation energy (Ea) for polymer decomposition using thermogravimetric analysis (TGA). The method uses multiple dynamic heating-rate TG runs to derive Ea from the temperature dependence of decomposition according to the Arrhenius relationship. It applies only when the decomposition proceeds by a single mechanism or by clearly separated single-stage steps in a multistage reaction.

Key Topics

• Principle: heating specimens at several heating rates, measuring mass change vs temperature, selecting temperatures at given degrees of conversion (C), and calculating Ea from the slope of log(heating rate) vs 1/T plots using the Ozawa / Flynn–Wall approximation.
• Test conditions and apparatus: refers to ISO 11358-1 for general TG principles, apparatus requirements, and calibration (mass and temperature).
• Specimen preparation: powders, pellets, flakes, filaments or film; small particle size preferred (grinding in liquid-nitrogen mill acceptable).
• Experimental parameters:
  • Use three or more heating rates; lowest and highest heating rates must differ by a factor ≥ 5.
  • Preferred specimen mass