oSIST prEN ISO 1628-3:2026

SLOVENSKI STANDARD
01-september-2026
Polimerni materiali - Ugotavljanje viskoznosti polimernih materialov v razredčeni
raztopini z uporabo kapilarnega viskozimetra - 3. del: Polietileni in polipropileni
(ISO/DIS 1628-3:2026)
Plastics - Determination of the viscosity of polymers in dilute solution using capillary
viscometers - Part 3: Polyethylenes and polypropylenes (ISO/DIS 1628-3:2026)
Kunststoffe - Bestimmung der Viskosität von Polymeren in verdünnter Lösung durch ein
Kapillarviskosimeter - Teil 3: Polyethylen und Polypropylen (ISO/DIS 1628-3:2026)
Plastiques - Détermination de la viscosité des polymères en solution diluée à l'aide de
viscosimètres à capillaires - Partie 3: Polyéthylènes et polypropylènes (ISO/DIS 1628-
3:2026)
Ta slovenski standard je istoveten z: prEN ISO 1628-3
ICS:
83.080.20 Plastomeri Thermoplastic materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 1628-3
ISO/TC 61/SC 9
Plastics — Determination of
Secretariat: KATS
the viscosity of polymers in
Voting begins on:
dilute solution using capillary
2026-06-16
viscometers —
Voting terminates on:
2026-09-08
Part 3:
Polyethylenes and polypropylenes
Plastiques — Détermination de la viscosité des polymères en
solution diluée à l'aide de viscosimètres à capillaires —
Partie 3: Polyéthylènes et polypropylènes
ICS: 83.080.20
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
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Reference number
ISO/DIS 1628-3:2026(en)
DRAFT
ISO/DIS 1628-3:2026(en)
International
Standard
ISO/DIS 1628-3
ISO/TC 61/SC 9
Plastics — Determination of
Secretariat: KATS
the viscosity of polymers in
Voting begins on:
dilute solution using capillary
2026-06-16
viscometers —
Voting terminates on:
2026-09-08
Part 3:
Polyethylenes and polypropylenes
Plastiques — Détermination de la viscosité des polymères en
solution diluée à l'aide de viscosimètres à capillaires —
Partie 3: Polyéthylènes et polypropylènes
ICS: 83.080.20
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 2026
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
ISO/CEN PARALLEL PROCESSING
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BE CONSIDERED IN THE LIGHT OF THEIR
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Published in Switzerland Reference number
ISO/DIS 1628-3:2026(en)
ii
ISO/DIS 1628-3:2026(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
4.1 General .1
4.2 Method A – Efflux time method . .1
4.3 Method B – Differential pressure method.2
5 Solvent . 2
6 Apparatus . 2
6.1 Efflux time method .2
6.2 Differential pressure method .4
7 Test sample . 5
8 Procedure . 5
8.1 Efflux time method .5
8.1.1 Cleaning the viscometer .5
8.1.2 Measurement of efflux time of solvent .5
8.1.3 Choice of polymer solution concentration .5
8.1.4 Preparation of the solution .6
8.1.5 Measurement of efflux time of solution .7
8.2 Differential pressure method .7
8.2.1 Choice of polymer solution concentration .7
8.2.2 Viscosity ratio increment . . .7
8.2.3 Determination of the polymer solution concentration .7
9 Expression of results . 8
9.1 Reduced viscosity, I .8
9.2 Intrinsic viscosity, [η] .8
9.3 Precision . . .9
10 Test report . 9
Bibliography .10

iii
ISO/DIS 1628-3:2026(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 1628-3 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 9, Thermoplastic
materials.
This fourth edition cancels and replaces the third edition, which has been technically revised. The main
change is the incorporation of an alternative procedure, the differential pressure method (following same
change in ISO 1628-1:2024), based on comparing the differential pressure in capillary tubing due to the flow
of polymer solution and neat solvent simultaneously.
ISO 1628 consists of the following parts, under the general title Plastics — Determination of the viscosity of
polymers in dilute solution using capillary viscometers:
— Part 1: General principles
— Part 2: Poly(vinyl chloride) resins
— Part 3: Polyethylenes and polypropylenes
— Part 4: Polycarbonate (PC) moulding and extrusion materials
— Part 5: Thermoplastic polyester (TP) homopolymers and copolymers
— Part 6: Methyl methacrylate polymers

iv
DRAFT International Standard ISO/DIS 1628-3:2026(en)
Plastics — Determination of the viscosity of polymers in
dilute solution using capillary viscometers —
Part 3:
Polyethylenes and polypropylenes
1 Scope
This part of ISO 1628 defines particular conditions for determining the reduced viscosity (also known as
viscosity number) and intrinsic viscosity of polyethylenes and polypropylenes at elevated temperatures
(135 °C – 160 °C) in dilute solution.
The viscosity of polymer solutions can be affected by fillers or additives present in the sample. The value of
a reduced viscosity determined by this method can therefore be unreliable if the sample contains fillers or
other additives.
NOTE Reduced viscosity is also known as the Staudinger function (J ) and intrinsic viscosity as the Staudinger
v
index (J ).
g
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 1628-1:2024, Plastics — Determination of the viscosity of polymers in dilute solution using capillary
viscometers — Part 1: General principles
ISO 3105:1994, Glass capillary kinematic viscometers — Specifications and operating instructions
3 Terms and definitions
There are no terms and definitions in this document.
4 Principle
4.1 General
Ethylene polymers and isotactic polypropylenes are not soluble at room temperature in any known solvents.
Precautions shall therefore be taken during the test to avoid any precipitation of polymer, which would give
an incorrect solution concentration.
The dissolution and test temperatures shall be chosen with the above precautions.
4.2 Method A – Efflux time method
The times of flow of a solvent and a solution of polymer at a specified concentration in that solvent are
measured at elevated temperature. The reduced viscosity and intrinsic viscosity are calculated from
these measurements and from the known concentration of the solution, using an appropriate Ubbelohde
viscometer.
ISO/DIS 1628-3:2026(en)
4.3 Method B – Differential pressure method
The differential pressure across each of the 2 capillaries connected in series, one of them receiving the
solvent having the differential pressure ∆p , the other receiving the polymer solution having the differential
pressure ∆p, are measured at elevated temperature. The reduced viscosity and intrinsic viscosity are
calculated from these measurements and from the known concentration of the solution.
5 Solvent
5.1 The solution viscosity obtained by this method depends on the solvent used, although the solution
viscosities of polyolefin in different solvents are correlated. The reference solvent is decahydronaphtalene
which is primarily used in the manual efflux time method, while chlorinated solvents may be used and allow
the application of online concentration detectors in automated instruments.
5.2 Decahydronaphthalene, analytical-reagent grade, re-distilled at a temperature not higher than 65 °C
and a pressure of approximately 500 Pa; its per-oxidation shall be prevented by suitable means, for example
distilling in the presence
...