ISO 247-2:2018

Rubber - Determination of ash - Part 2: Thermogravimetric analysis (TGA)

This document specifies two methods for the determination of ash from raw rubbers, compounded rubbers and vulcanizates using a thermogravimetric analyser (TGA). The methods are applicable to raw, compounded or vulcanized rubbers of the M, O, R and U families described in ISO 1629: - Method A is applicable for the determination of the ash from raw rubbers. - Method B is applicable for the determination of the ash from compounded or vulcanized rubbers. The methods are not applicable for the determination of the ash from raw rubbers, compounded or vulcanized rubbers containing chlorine, bromine or iodine. This document does not cover the interpretation of the ash results from the inorganic chemical contents of compounded or vulcanized rubbers.

Caoutchouc — Détermination du taux de cendres — Partie 2: Analyse thermogravimétrique (TGA)

General Information

• Status: Published
• Publication Date: 24-Jul-2018
• ICS: 83.060 - Rubber
• Technical Committee: ISO/TC 45/SC 2 - Testing and analysis
• Drafting Committee: ISO/TC 45/SC 2/WG 5 - Chemical tests
• Current Stage: 9093 - International Standard confirmed
• Start Date: 05-Jan-2024
• Completion Date: 13-Dec-2025

Relations

• Consolidated By: ISO 11607-1:2019/Amd 1:2023 - Packaging for terminally sterilized medical devices - Part 1: Requirements for materials, sterile barrier systems and packaging systems - Amendment 1: Application of risk management
• Effective Date: 06-Jun-2022

Overview

ISO 247-2:2018 - "Rubber - Determination of ash - Part 2: Thermogravimetric analysis (TGA)" specifies two TGA-based methods for measuring ash content in raw rubbers, compounded rubbers and vulcanizates. The standard applies to rubbers of the M, O, R and U families (ISO 1629 nomenclature). It describes sample preparation, instrument settings, calibration, test procedures (Method A for raw rubber; Method B for compounded/vulcanized rubber) and expression of results. Note: the methods are not applicable to rubbers containing chlorine, bromine or iodine, and the standard does not interpret ash in terms of inorganic chemistry.

Key topics and technical requirements

• Test principle: Thermogravimetric analysis - the sample is heated under nitrogen to decompose polymeric material, then switched to oxygen/air to burn carbonaceous residue; the remaining mass is reported as ash.
• Methods:
  • Method A - for raw rubbers. Typical TGA program: heat to 500 °C in N2, then to 550 °C in O2/air until constant mass.
  • Method B - for compounded or vulcanized rubbers. Typical program: heat to 550 °C in N2, then to 650 °C (or up to 850 °C for inorganic fillers like CaCO3) in O2/air until constant mass.
• Sample size & prep: Test portions typically 10–20 mg taken from homogenized or milled material per ISO 1795 and ISO 248-1 guidance.
• Apparatus & gases:
  • Thermogravimetric analyser with thermo-balance, furnace, temperature programmer and gas flow control.
  • Sample pans (platinum or alumina); analytical balance capable of 0.1 mg.
  • Dry nitrogen and oxygen (or dry air) with ≥ 99.99% purity.
• Calibration & precision: Temperature and mass calibration per manufacturer; recommended periodic mass calibration (e.g., monthly). The standard includes precision data from an interlaboratory study.
• Reporting: Include reference to ISO 247-2:2018, method used, heating rates, final temperatures, apparatus type, results and any deviations.

Applications and who uses it

• Quality control laboratories performing routine rubber testing and incoming inspection.
• Rubber manufacturers and compounders verifying ash (inorganic residue) levels in raw materials, compounds and finished vulcanizates.
• R&D and formulation teams assessing filler and inorganic content effects on performance (note: ISO 247-2 does not provide chemical interpretation of ash).
• Third‑party testing and certification bodies requiring standardized, reproducible ash determinations using TGA.

Related standards

• ISO 1629 - Rubber nomenclature (M, O, R, U families)
• ISO 248-1 - Determination of volatile-matter content (hot‑mill/oven)
• ISO 1795 - Sampling and preparative procedures
• ISO 19983 - Precision of rubber test methods

Keywords: ISO 247-2:2018, thermogravimetric analysis, TGA, ash determination, rubber testing, compounded rubbers, vulcanizates, rubber quality control, TGA calibration.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 247-2
First edition
2018-07
Rubber — Determination of ash —
Part 2:
Thermogravimetric analysis (TGA)
Caoutchouc — Détermination du taux de cendres —
Partie 2: Analyse thermogravimétrique (TGA)
Reference number
©
ISO 2018
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents . 2
6 Apparatus . 2
7 Preparation of the test sample . 2
8 Calibration . 2
9 Procedure. 3
9.1 Method A . 3
9.2 Method B . 3
10 Expression of results . 3
11 Precision . 4
12 Test report . 4
Annex A (informative) Precision . 5
Bibliography . 7
Foreword
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URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 45, Rubber and rubber products,
Subcommittee SC 2, Testing and analysis.
A list of all parts in the ISO 247 series can be found on the ISO website.
iv © ISO 2018 – All rights reserved

INTERNATIONAL STANDARD ISO 247-2:2018(E)
Rubber — Determination of ash —
Part 2:
Thermogravimetric analysis (TGA)
WARNING 1 — Persons using this document should be familiar with normal laboratory practice.
This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to
determine the applicability of any other restrictions.
WARNING 2 — Certain procedures specified in this document might involve the use or generation
of substances, or the generation of waste, that could constitute a local environmental hazard.
Reference should be made to appropriate documentation on safe handling and disposal after use.
1 Scope
This document specifies two methods for the determination of ash from raw rubbers, compounded
rubbers and vulcanizates using a thermogravimetric analyser (TGA).
The methods are applicable to raw, compounded or vulcanized rubbers of the M, O, R and U families
described in ISO 1629:
— Method A is applicable for the determination of the ash from raw rubbers.
— Method B is applicable for the determination of the ash from compounded or vulcanized rubbers.
The methods are not applicable for the determination of the ash from raw rubbers, compounded or
vulcanized rubbers containing chlorine, bromine or iodine.
This document does not cover the interpretation of the ash results from the inorganic chemical contents
of compounded or vulcanized rubbers.
2 Normative references
The following documents are referred to in the text in such a way that some or all of the
...