prEN ISO 3451-1

SLOVENSKI STANDARD
01-september-2025
Polimerni materiali - Določanje pepela - 1. del: Splošne metode (ISO/DIS 3451-
1:2025)
Plastics - Determination of ash - Part 1: General methods (ISO/DIS 3451-1:2025)
Kunststoffe - Bestimmung der Asche - Teil 1: Allgemeine Verfahren (ISO/DIS 3451-
1:2025)
Plastiques - Détermination du taux de cendres - Partie 1: Méthodes générales (ISO/DIS
3451-1:2025)
Ta slovenski standard je istoveten z: prEN ISO 3451-1
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 3451-1
ISO/TC 61/SC 5
Plastics — Determination of ash —
Secretariat: DIN
Part 1:
Voting begins on:
General methods 2025-07-03
Voting terminates on:
Plastiques — Détermination du taux de cendres —
2025-09-25
Partie 1: Méthodes générales
ICS: 83.080.01
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
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Reference number
ISO/DIS 3451-1:2025(en)
DRAFT
ISO/DIS 3451-1:2025(en)
International
Standard
ISO/DIS 3451-1
ISO/TC 61/SC 5
Plastics — Determination of ash —
Secretariat: DIN
Part 1:
Voting begins on:
General methods
Voting terminates on:
Plastiques — Détermination du taux de cendres —
Partie 1: Méthodes générales
ICS: 83.080.01
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
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Published in Switzerland Reference number
ISO/DIS 3451-1:2025(en)
ii
ISO/DIS 3451-1:2025(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents (for methods B and C only) . 2
6 Apparatus . 2
7 Procedure . 3
7.1 Test portion .3
7.1.1 General .3
7.1.2 Methods A, B, C or D .4
7.1.3 Method E .4
7.2 Test conditions .4
7.3 Method A — Direct calcination .5
7.4 Method B — Calcination following sulfuric acid treatment after burning .6
7.5 Method C — Calcination following sulfuric acid treatment before burning .6
7.6 Method D —Automated instrument method .6
7.7 Method E .7
8 Number of tests . 8
9 Expression of results . 8
10 Precision . 8
11 Test report . 9
Bibliography .10

iii
ISO/DIS 3451-1:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 5, Physical-
chemical properties, in collaboration with the European Committee for Standardization (CEN) Technical
Committee CEN/TC 249, Plastics, in accordance with the Agreement on technical cooperation between ISO
and CEN (Vienna Agreement).
This sixth edition cancels and replaces the fifth edition (ISO 3451-1:2019), which has been technically
revised.
The main changes are as follows:
— an additional test tempeature of 1 100 °C has been added;
— the thermogravimetry has been added as alternative test method.
A list of all parts in the ISO 3451 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
DRAFT International Standard ISO/DIS 3451-1:2025(en)
Plastics — Determination of ash —
Part 1:
General methods
WARNING — The use of this document may involve hazardous chemicals, materials, operations or
equipment. This document does not purport to address the safety problems associated with its use.
It is the responsibility of the user of this document to establish proper safety and health practices
and determine the application of regulatory limitations prior to use.
1 Scope
This document specifies general methods, with suitable test conditions, for the determination of the ash
of a range of plastics. The particular conditions chosen can be included in the specifications for the plastic
material in question.
Particular conditions applicable to poly(alkylene terephthalate) materials, unplasticized cellulose acetate,
polyamides and poly(vinyl chloride) plastics, including some specific filled, glass-fibre-reinforced and flame-
retarded materials, are specified in ISO 3451-2, ISO 3451-3, ISO 3451-4 and ISO 3451-5.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 472, Plastics — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 472 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
It is possible to determine the ash of an organic material by five main methods (methods A, B, C, D and E).
a) Direct calcination, i.e. by burning the organic matter and heating the residue at high temperature until
constant mass is reached, which may be carried out by two different procedures:
— burning with, for example, a Bunsen burner and one or more calcining steps in a muffle furnace
(method A);
— burning and calcining as one single step in a muffle furnace (method A — rapid ashing), if it can be
demonstrated that the rapid ashing yields the same results as method A.

ISO/DIS 3451-1:2025(en)
b) Calcination after sulfation, which may be carried out by two different procedures:
— with sulfuric acid treatment after burning, i.e. by burning the organic matter, transforming the
inorganic residue into sulfates with concentrated sulfuric acid and heating the residue at high
temperature until constant mass is reached. This is the common method of obtaining “sulfated ash”
(method B);
— with sulfuric acid treatment before burning, i.e. by heating the organic matter together with
concentrated sulfuric acid up to temperatures where fuming and subsequent burning of the organic
matter occur, and finally heating the residue at high temperature until constant mass is reached
(method C). This procedure may be used if volatile metal halides are liable to evaporate during
burning of the organic matter. It is not applicable to silicones or fluorine-containing polymers.
c) Automated instrument method (method D);
d) Thermogravimetric method (method E).
In each case, the final step of the procedure is calcination at a pre-defined temperature (see 7.2).
NOTE The mass of the ash can vary with the temperature of calcination. For example, higher temperatures such
as 850 °C convert calcium carbonate and other carbonates to their oxides and thus give lower values for the ash.
5 Reagents (for methods B and C only)
During the analysis, only reagents of analytical grade and only distilled water or water of equivalent purity
shall be used.
5.1 Ammonium carbonate, anhydrous.
5.2 Ammonium nitrate, approximately 10 % (by mass) solution.
5.3 Sulfuric acid, concentrated 98 % (by volume), ρ = 1,84 g/cm .
WARNING — Sulfuric acid is highly corrosive. It shall be handled with suitable skin and eye protection
in a fume cupboard. It reacts exothermically with water.
5.4 Sulfuric acid, 50 % (by volume) solution.
WARNING — Sulfuric acid shall be handled with care. The sulfuric acid shall be prepared by slowly
adding the concentrated acid to water.
6 Apparatus
Some of the listed items may not be necessary for each method.
6.1 Crucible, made of silica, porcelain, ceramics, fibres, quartz, glass or platinum, thereof, inert to the
material tested and suitable for the temperatures used. The use of a crucible lid/watch-glass may be
beneficial for samples producing a fine particulate ash.
6.2 Gas burner, or other appropriate heat source.
6.3 Muffle furnace, powered by electric resistance heating or by microwave heating, capable of being
maintained at (600 ± 25) °C, (750 ± 50) °C, (850 ± 50) °C, (950 ± 50) °C or (1 100 ± 50) °C, as appropriate,
capable of measuring of temperature signals with an accuracy of ±2 % or better.
6.4 Analytical balance, for methods A, B, C or D, capable of determination of masses of test portions
according to Table 1 with an accuracy of 0,1 mg.

ISO/DIS 3451-1:2025(en)
6.5 Thermobalance, for method E, operated in air atmosphere and capable of heating up to and being
maintained at (600 ± 5) °C, (750 ± 5) °C, (850 ± 5) °C, (950 ± 5) °C or (1 100 ± 5) °C, as appropriate, and
continuously monitoring test temperatures with an accuracy of ±1 % or better of the absolute temperature
measured in K and masses of test portions according to Table 1 with an accuracy of ±20 µg or better.
6.6 For automated instruments and thermobalances, the following requirements apply:
— fully automatic analysis instrument with integrated drying oven or drying purge gas, muffle furnace or
other built-in heating device, analytical balance and a sample turntable.
— loss of weight during the drying and ashing process is continuously monitored during the ashing process;
— the built-in analytical balance can weigh each sample in turn, and the results recorded by the software;
— instrument shall have a method to correct the mass difference caused by buoyancy, thus the weighing
can be taken at different temperature, samples do not need to be cooled down during test;
— having a furnace that operates at the prescribed temperature, capable of being maintained at (600 ± 25) °C,
(750 ± 50) °C, (850 ± 50) °C, (950 ± 50) °C or (1 100 °C ± 50) °C for automated instruments and (600 ± 5) °C,
(750 ± 5) °C, (850 ± 5) °C, (950 ± 5) °C or (1 100 °C ± 5) °C for thermobalances respectively, as appropriate;
— having a holder for one or more crucibles, e.g. by using a turntable, or an automatic way to introduce and
extract the crucibles consecutively into and from the furnace;
— recording device capable of automatically recording the
...