ISO/PRF 1183-2

2026-01
ISO/TC 61/SC 5
Secretariat: DIN
Date: 2026-02-05
Plastics — Methods for determining the density of non-cellular
plastics —
Part 2:
Density gradient column method
Plastiques — Méthodes de détermination de la masse volumique des plastiques —
non alvéolaires —
Partie 2: Méthode de la colonne à gradient de masse volumique
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PROOF
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Contents Page
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions . 1
3.2 Symbols . 2
4 Conditioning . 2
5 Method . 2
5.1 Apparatus . 2
5.2 Immersion liquids . 2
5.3 Specimens . 3
5.4 Procedure . 3
6 Test report . 5
Annex A (informative) Liquid systems suitable for density determinations . 6
Annex B (informative) Preparation of density gradient column . 7
Bibliography . 13

iv
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
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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 document 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).
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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 third edition cancels and replaces the second edition (ISO 1183-2:2019), which has been technically
revised. The main changes are as follows:
— — reference to this document, any deviations and any unusual features observed have been added to the
test report.
A list of all parts in the ISO 1183 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.
v
Introduction
Density is frequently used to follow variations in physical structure or composition of plastic materials.
Density can also be useful in assessing the uniformity of samples or specimens. The density of plastic materials
can depend upon the choice of specimen preparation method. When this is the case, precise details of the
specimen preparation method are intended to be included in the appropriate material specification.
vi
Plastics — Methods for determining the density of non-cellular
plastics —
Part 2:
Density gradient column method
WARNING — The use of this document may involve hazardous materials, operations or equipment.
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 of this document to establish appropriate health and safety practices.
1 Scope
This document specifies a gradient column method for the determination of the density of non-cellular
moulded or extruded plastics or pellets in void-free form.
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 291, Plastics — Standard atmospheres for conditioning and testing
ISO 1183--1, Plastics — Methods for determining the density of non-cellular plastics — Part 1: Immersion
method, liquid pycnometer method and titration method
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions 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/
3.1.1 3.1.1
density
ρ
3 3 3
ratio of the mass m of a sample to its volume V (at the temperature T) expressed in kg/m , kg/dm (g/cm ), or
kg/l (g/ml)
[ [1] ]
Note 1 to entry: The following terms, based upon ISO 80000-4, 1 , are given in 3.23.2 for clarification.
3.1.2 3.1.2
density gradient column
column containing a mixture of two liquids, the density in the column increasing uniformly from top to bottom
ISO/DIS PRF 1183-2:2025(E2026(en)
3.2 Symbols
Term Symbol Formulation Units
kg/m
3 3
Density ρ m/V kg/dm (g/cm )
kg/l (g/ml)
m /kg
3 3
Specific volume ν V/m (= 1/ρ) dm /kg (cm /g)
l/kg (ml/g)
4 Conditioning
Conditioning and testing shall be in accordance with ISO 291 or the appropriate material standard. In general,
conditioning specimens to constant temperature is not required, because the determination itself brings the
specimen to the constant temperature of the test.
Specimens which change in density during the test to such an extent that the change is greater than the
required accuracy of the density determination shall be conditioned prior to measurement in accordance with
the applicable material specification. When changes in density with time or atmospheric conditions are the
primary purpose of the measurements, the specimens shall be conditioned as specified in the material
specification and, if no material specification exists, then as agreed upon by the interested parties.
5 Method
5.1 Apparatus
5.1.1 5.1.1 Density gradient column, consisting of a suitable graduated column, not less than 40 mm in
diameter, with a cover. The height of the column shall be compatible with the accuracy required. A
graduation interval of 1 mm for the scale on the column is normal.
5.1.2 5.1.2 Liquid bath, capable of being thermostatically controlled to within ±0,1 K or ±0,5 K, depending
on the sensitivity required (see Annex BAnnex B).).
5.1.3 5.1.3 Calibrated glass floats, covering the density range in which measurements are to be made
and approximately evenly distributed throughout this range.
These can be purchased from an accredited source or prepared as specified in 5.4.15.4.1.
5.1.4 5.1.4 Balance, accurate to ±0,1 mg.
5.1.5 5.1.5 Siphon or capillary filling tube, for filling the gradient column (5.1.1(5.1.1),), as shown in
Figure B.1Figure B.1 or Figure B.2Figure B.2,, or any other suitable device.
5.2 Immersion liquids
Required are two miscible liquids of different densities, freshly distilled in the case of pure liquids. The
densities of various liquids are given in Annex AAnnex A as a guide.
ii
The liquid with which the specimen comes into contact during the measurement shall have no effect on the
specimen.
Prepare the mixture of liquids as specified in 5.4.1.25.4.1.2.
5.3 Specimens
Specimens shall consist of pieces of the material cut to any convenient shape for ease of identification. The
dimensions of each piece shall be chosen to permit accurate measurement of the position of the centre of the
piece.
When cutting specimens from larger samples, care shall be taken to ensure that the characteristics of the
material are not changed due to excessive heat generation. The surface of the specimen shall be smooth and
free from cavities to minimize the entrapment of air bubbles upon immersion in the liquid, otherwise errors
will be introduced.
NOTE Specimens of less than 5 mm in diameter are normally suitable.
5.4 Procedure
5.4.1 Preparation and calibration of glass floats
5.4.1.1 5.4.1.1 The glass floats (5.1.3(5.1.3)) may be produced by any convenient method.
They shall be approximately spherical, of diameter not greater than 5 mm and fully annealed.
5.4.1.2 5.4.1.2 To prepare the glass floats for use, prepare a series of mixtures of about 500 ml
of the two immersion liquids (5.2(
...