ISO 11358-1:2022

Overview

ISO 11358-1:2022 - Plastics - Thermogravimetry (TG) of polymers - Part 1: General principles - defines general principles and conditions for thermogravimetric analysis (TGA/TG) of polymers. It applies to liquids and solids (pellets, granules, powders or fabricated shapes reduced to test size) and establishes procedures to record mass change as a function of temperature or time. The standard supports both dynamic (temperature-scanning) and isothermal TG measurements, and covers testing in different atmospheres (inert, oxidizing or reactive) to separate decomposition from oxidative degradation.

Key topics and technical requirements

• Scope and purpose: methods for investigating physical effects and chemical reactions associated with mass changes; determination of decomposition temperatures and rates; measurement of volatiles, additives and fillers.
• Measurement modes: dynamic mass‑change determination (mass vs temperature at programmed heating rates) and isothermal mass‑change determination (mass vs time at constant temperature).
• Apparatus (thermobalance): capability for controlled heating/cooling, temperature stability (≤ ±0.3 K), mass measurement accuracy (≤ ±20 µg), temperature measurement accuracy (≈ ±1% of absolute K), and time measurement (±1 s). Instruments may provide differential TG (DTG) curves.
• Purge gas quality: dry air/oxygen for oxidizing conditions or inert gas with O2 ≤ 0.001% by volume for non‑oxidizing conditions; water content < 0.001% by mass.
• Sample preparation and conditioning: guidance for liquids and solids, specimen size/shape considerations, and conditioning in standard atmospheres (ISO 291) unless otherwise specified.
• Calibration:
  • Mass calibration using calibrated weights under static purge gas.
  • Temperature calibration (Curie‑point method) using calibration materials and the same crucible, gas and heating conditions as testing.
• Data treatment: graphical representation of TG curves, procedures for single- and multi‑stage mass loss analysis, residue determination, and buoyancy correction (included in this edition).

Applications and users

ISO 11358-1:2022 is used for:

• Evaluating thermal stability and decomposition behaviour of polymers
• Quantifying volatile content, additives and fillers
• Separating oxidative versus inert decomposition pathways
• Supporting process development, quality control and materials R&D

Typical users:

• Polymer testing laboratories and QA/QC teams
• Materials scientists and R&D engineers
• Thermoanalytical instrument manufacturers and service providers
• Regulatory and certification bodies assessing thermal properties

Related standards

• ISO 291 - Plastics: standard atmospheres for conditioning and testing (referenced)
• ISO 472 - Plastics vocabulary (referenced)
• Other parts of the ISO 11358 series (see ISO website for full listing)

Keywords: ISO 11358-1:2022, thermogravimetry, thermogravimetric analysis, TG of polymers, thermobalance, TGA, thermal stability, Curie-point calibration, buoyancy correction, dynamic mode, isothermal mode.