Plastics - Determination of the viscosity of polymers in dilute solution using capillary viscometers - Part 1: General principles (ISO 1628-1:2021)

This document defines the general conditions for the determination of the reduced viscosity, intrinsic viscosity and K‑value of organic polymers in dilute solution. It defines the standard parameters that are applied to viscosity measurement.
This document is used to develop standards for measuring the viscosities in solution of individual types of polymer. It is also used to measure and report the viscosities of polymers in solution for which no separate standards exist.

Kunststoffe - Bestimmung der Viskosität von Polymeren in verdünnter Lösung durch ein Kapillarviskosimeter - Teil 1: Allgemeine Grundlagen (ISO 1628-1:2021)

Dieses Dokument legt die allgemeinen Grundlagen für die Bestimmung der reduzierten Viskosität, der intrinsischen Viskosität und des K Wertes von organischen Polymeren in verdünnter Lösung fest. Es legt die bei Viskositätsmessungen angewendeten genormten Parameter fest.
Dieses Dokument wird für die Erarbeitung von Normen zur Messung der Viskositäten bestimmter Polymere in verdünnter Lösung herangezogen. Dieses Dokument wird auch zur Bestimmung der Viskositäten von Polymeren in verdünnter Lösung angewendet, für die es keine spezielle Norm gibt.

Plastiques - Détermination de la viscosité des polymères en solution diluée à l'aide de viscosimètres à capillaires - Partie 1: Principes généraux (ISO 1628-1:2021)

Le présent document définit les conditions générales nécessaires pour déterminer la viscosité réduite, la viscosité intrinsèque et la valeur K des polymères organiques en solution diluée. Il définit les paramètres normalisés qui sont appliqués au mesurage de la viscosité.
Le présent document est utilisé pour élaborer des normes concernant le mesurage de la viscosité de différents types de polymères en solution. Il est également utilisé pour mesurer et exprimer les viscosités des polymères en solution qui ne font l'objet d'aucune norme distincte.

Polimerni materiali - Določanje viskoznosti polimerov v razredčenih raztopinah s kapilarnimi viskozimetri - 1. del: Splošna načela (ISO 1628-1:2021)

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Published
Publication Date
16-Mar-2021
Withdrawal Date
29-Sep-2021
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Start Date
17-Mar-2021
Completion Date
17-Mar-2021

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SLOVENSKI STANDARD
SIST EN ISO 1628-1:2021
01-maj-2021
Nadomešča:
SIST EN ISO 1628-1:2009
SIST EN ISO 1628-1:2009/A1:2012
Polimerni materiali - Določanje viskoznosti polimerov v razredčenih raztopinah s
kapilarnimi viskozimetri - 1. del: Splošna načela (ISO 1628-1:2021)
Plastics - Determination of the viscosity of polymers in dilute solution using capillary
viscometers - Part 1: General principles (ISO 1628-1:2021)
Kunststoffe - Bestimmung der Viskosität von Polymeren in verdünnter Lösung durch ein
Kapillarviskosimeter - Teil 1: Allgemeine Grundlagen (ISO 1628-1:2021)
Plastiques - Détermination de la viscosité des polymères en solution diluée à l'aide de
viscosimètres à capillaires - Partie 1: Principes généraux (ISO 1628-1:2021)
Ta slovenski standard je istoveten z: EN ISO 1628-1:2021
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 1628-1:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 1628-1:2021

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SIST EN ISO 1628-1:2021


EN ISO 1628-1
EUROPEAN STANDARD

NORME EUROPÉENNE

March 2021
EUROPÄISCHE NORM
ICS 83.080.01 Supersedes EN ISO 1628-1:2009
English Version

Plastics - Determination of the viscosity of polymers in
dilute solution using capillary viscometers - Part 1:
General principles (ISO 1628-1:2021)
Plastiques - Détermination de la viscosité des Kunststoffe - Bestimmung der Viskosität von
polymères en solution diluée à l'aide de viscosimètres Polymeren in verdünnter Lösung durch ein
à capillaires - Partie 1: Principes généraux (ISO 1628- Kapillarviskosimeter - Teil 1: Allgemeine Grundlagen
1:2021) (ISO 1628-1:2021)
This European Standard was approved by CEN on 23 February 2021.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 1628-1:2021 E
worldwide for CEN national Members.

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SIST EN ISO 1628-1:2021
EN ISO 1628-1:2021 (E)
Contents Page
European foreword . 3

2

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SIST EN ISO 1628-1:2021
EN ISO 1628-1:2021 (E)
European foreword
This document (EN ISO 1628-1:2021) has been prepared by Technical Committee ISO/TC 61 "Plastics"
in collaboration with Technical Committee CEN/TC 249 “Plastics” the secretariat of which is held by
NBN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by September 2021, and conflicting national standards
shall be withdrawn at the latest by September 2021.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 1628-1:2009.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 1628-1:2021 has been approved by CEN as EN ISO 1628-1:2021 without any
modification.

3

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SIST EN ISO 1628-1:2021

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SIST EN ISO 1628-1:2021
INTERNATIONAL ISO
STANDARD 1628-1
Fourth edition
2021-02
Plastics — Determination of the
viscosity of polymers in dilute solution
using capillary viscometers —
Part 1:
General principles
Plastiques — Détermination de la viscosité des polymères en solution
diluée à l'aide de viscosimètres à capillaires —
Partie 1: Principes généraux
Reference number
ISO 1628-1:2021(E)
©
ISO 2021

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SIST EN ISO 1628-1:2021
ISO 1628-1:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

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SIST EN ISO 1628-1:2021
ISO 1628-1:2021(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Terms related to any liquid . 1
3.2 Terms related to polymer solutions . 2
4 Principle . 4
5 Apparatus . 5
6 Solutions . 8
6.1 Preparation . 8
6.2 Concentration. 9
7 Temperature of measurement . 9
8 Procedure. 9
8.1 General . 9
8.2 Preparing and charging the viscometer . 9
8.3 Efflux time measurement .10
9 Expression of results .10
9.1 Reduced viscosity and intrinsic viscosity .10
9.2 K-value .11
10 Test report .11
Annex A (normative) Cleaning of apparatus .12
Annex B (informative) Notes on sources of error .13
Bibliography .16
© ISO 2021 – All rights reserved iii

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SIST EN ISO 1628-1:2021
ISO 1628-1:2021(E)

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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
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 fourth edition cancels and replaces the third edition (ISO 1628-1:2009), which has been technically
revised. It also incorporates the Amendment 1 ISO 1628-1:2009/Amd 1:2012.
The main changes compared to the previous edition are as follows:
— ISO 3205 (withdrawn) has been deleted from Clause 2;
— the figure keys have been revised;
— nominal viscometer constant has been added to Table 1;
A list of all parts in the ISO 1628 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 © ISO 2021 – All rights reserved

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SIST EN ISO 1628-1:2021
INTERNATIONAL STANDARD ISO 1628-1:2021(E)
Plastics — Determination of the viscosity of polymers in
dilute solution using capillary viscometers —
Part 1:
General principles
1 Scope
This document defines the general conditions for the determination of the reduced viscosity, intrinsic
viscosity and K-value of organic polymers in dilute solution. It defines the standard parameters that are
applied to viscosity measurement.
This document is used to develop standards for measuring the viscosities in solution of individual types
of polymer. It is also used to measure and report the viscosities of polymers in solution for which no
separate standards exist.
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 3105, Glass capillary kinematic viscometers — Specifications and operating instructions
ISO 80000-1, Quantities and units — Part 1: General
ISO 80000-4, Quantities and units — Part 4: Mechanics
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 80000-1, ISO 80000-4 and the
following 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 http:// www .electropedia .org/
3.1 Terms related to any liquid
3.1.1
viscosity
property of a fluid sheared between two parallel plates, one of which moves relative to the other in
uniform rectilinear motion in its own plane, defined by the Newton formula

τη= γ
where
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SIST EN ISO 1628-1:2021
ISO 1628-1:2021(E)

τ is the shear stress;
η is the viscosity;

γ
dV
is the velocity gradient or rate of shear, given by where V is the velocity of one plane relative
dz
to the other and z the coordinate perpendicular to the two planes.
−1 −1
Note 1 to entry: The dimensions of viscosity are ML T .
Note 2 to entry: The units of viscosity are Pa·s.
−3
Note 3 to entry: For practical use, the sub-multiple 10 Pa·s is more convenient.
Note 4 to entry: Viscosity is usually taken to mean “Newtonian viscosity”, in which case the ratio of shearing
stress to velocity gradient is constant. In non-Newtonian behaviour, which is the usual case with high-
polymer solutions, the ratio varies with the shear rate. Such ratios are often called “apparent viscosities” at the
corresponding shear rate.
3.1.2
viscosity/density ratio
kinematic viscosity
v
ratio defined by the formula
η
v=
ρ
where ρ is the density of the fluid at the temperature at which the viscosity is measured
2 −1
Note 1 to entry: The dimensions of kinematic viscosity are L T .
2 −1
Note 2 to entry: The units of kinematic viscosity are m ·s .
−6 2 −1 2 −1
Note 3 to entry: For practical use, the sub-multiple 10 m ·s , i.e. mm ·s , is more convenient.
3.2 Terms related to polymer solutions
3.2.1
relative viscosity
viscosity ratio
η
r
ratio of the viscosity of the polymer solution (of stated concentration) η and the viscosity of the pure
solvent η , at the same temperature:
0
η
η =
r
η
0
Note 1 to entry: The ratio has no dimensions.
3.2.2
relative viscosity increment
viscosity ratio increment and specific viscosity
viscosity ratio minus one
ηη−
 
η
0
−=1
 
η η
 
0 0
Note 1 to entry: The increment has no dimensions.
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SIST EN ISO 1628-1:2021
ISO 1628-1:2021(E)

3.2.3
reduced viscosity
viscosity number
I
ratio of the relative viscosity increment to the polymer concentration c in the solution:
ηη−
0
Ι =
η c
0
3 −1
Note 1 to entry: The dimensions of reduced viscosity are L M .
3
Note 2 to entry: The units of reduced viscosity are m /kg.
−3 3 3
Note 3 to entry: For practical use, the sub-multiple 10 m /kg, i.e. cm /g, is more convenient and the commonly
quoted numerical values for reduced viscosity (viscosity number) use these practical units.
3
Note 4 to entry: The reduced viscosity is usually determined at low concentration (less than 5 kg/m , i.e. 0,005 g/
3
cm ), except in the case of polymers of low molar mass, for which higher concentrations is necessary.
3.2.4
inherent viscosity
logarithmic viscosity number
ratio of the natural logarithm of the viscosity ratio to the polymer concentration in the solution:
 
η
ln
 
η
 
0
c
Note 1 to entry: The dimensions and units are the same as those given in 3.2.3.
3
Note 2 to entry: The inherent viscosity is usually determined at low concentration (less than 5 kg/m , i.e. 0,005 g/
3
cm ), except in the case of polymers of low molar mass, for which higher concentrations is necessary.
3.2.5
intrinsic viscosity
limiting viscosity number
[η]
limiting value of the reduced viscosity or of the inherent viscosity (3.2.4) at infinite dilution:
ηη−
 
0
η = lim
[]
 
c→0 η c
 
0
η
 
ln
 
η
 
0
[]η = lim
c
c→0
Note 1 to entry: The dimensions and units are the same as those given in 3.2.3.
Note 2 to entry: The effect of the shear rate on the functions defined in 3.2.1 to 3.2.5 has been neglected, since
this effect is usually negligible for values of the reduced viscosity, inherent viscosity and intrinsic viscosity less
3 3
than 0,5 m /kg, i.e. 500 cm /g. Strictly speaking, all these functions can be defined at the limiting (preferably
infinitely small) value of the shear rate.
3.2.6
K-value
constant, independent of the concentration of the polymer solution and peculiar to the polymer sample,
which is a measure of the average degree of polymerization:
K-value=1 000 k
[1]
Note 1 to entry: According to H. Fikentscher , k is calculated as follows:
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SIST EN ISO 1628-1:2021
ISO 1628-1:2021(E)

2
 
75k
lgη = +kc100
 
r
1+150kc
 
and therefore
2
 
15,,lgηη−+11++21+ 51lg ,5lgη
 
rr r
c
 
k=
150+300c
where
η is the viscosity ratio (see 3.2.1);
η =
r
η
0
3 3 3
c is the concentration, in 10 kg/m , i.e. g/cm .
Note 2 to entry: A limiting viscosity number [η] can be calculated from k:
k
2
η =+230,375kk
[]
()
k
4 Principle
The data needed for the evaluation of the functions defined in 3.2 are obtained by means of a capillary-
tube viscometer. The efflux times of a given volume of solvent t and of solution t are measured at fixed
0
temperature and atmospheric-pressure conditions in the same viscometer. The efflux time of a liquid is
related to its viscosity by the Poiseuille-Hagenbach-Couette formula as shown in Formula (1):
η A
 
vC== t− (1)
 
2
ρ
t 
where
v is the viscosity/density ratio ;
C is a constant of the viscometer;
A is a parameter of the kinetic-energy correction;
ρ is the density of the liquid;
t is the efflux time.
A
 
For the purposes of this document, the kinetic energy correction shall be regarded as negligible
 
2
t 
when it is less than 3 % of the viscosity of the solvent. Hence, Formula (1) can be reduced to Formula (2):
η
vC== t (2)
ρ
Moreover, if the solution concentrations are limited so that the solvent density ρ and that of the
0
η
solution ρ differ by less than 0,5 %, the viscosity ratio will be given by the so-called “efflux time
η
0
t
ratio” .
t
0
The need for these constraints, and the consequences of not observing them, is described in Annex B.
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SIST EN ISO 1628-1:2021
ISO 1628-1:2021(E)

5 Apparatus
5.1 Capillary viscometer, of the suspended-level Ubbelohde type.
The use of a viscometer having the dimensions given in Figure 1 or Figure 2 is strongly recommended.
Furthermore, it is strongly recommended that the size of the viscometer be chosen from among those
listed in Table 1. The choice is determined by the viscosity/density ratio of the solvent at the temperature
of the measurement, as indicated in Table 1. The next-smaller viscometer may also be used.
Other types of viscometer listed in ISO 3105 may be used, provided they give results equivalent to those
given by the particular size of Ubbelohde viscometer chosen on the basis of the criteria specified in the
preceding paragraph. In cases of dispute, an Ubbelohde viscometer shall be used.
With automated apparatus, fitted with special timing devices, equivalent results with larger sizes of
capillary than those listed for the appropriate solvent viscosity/density ratio in Table 1 can be obtained.
5.2 Viscometer holder, suitable to hold the viscometer firmly in the thermostatic bath (5.3) in the
vertical position.
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SIST EN ISO 1628-1:2021
ISO 1628-1:2021(E)

Dimensions in millimetres
Key
A lower reservoir 26 mm internal diameter L mounting tube 11 mm internal diameter
B suspended level bulb M lower vent tube 6 mm internal diameter
C timing bulb N upper vent tube 7 mm internal diameter
D upper reservoir P connecting tube
E and F timing marks R working capillary
G and H filling marks
Figure 1 — Ubbelohde viscometer
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SIST EN ISO 1628-1:2021
ISO 1628-1:2021(E)

5.3 Thermostatic bath, transparent liquid or vapour bath of a size such that, during the measurement,
all sections containing test liquid are at least 20 mm below the surface of the bath medium and at least
20 mm away from all boundaries of the bath tank.
The temperature control shall be such that, within the range 25 °C to 100 °C, the temperature of the bath
does not vary from the specified temperature by more than 0,05 K over the length of the viscometer, or
between the viscometers if several determinations are carried out simultaneously.
At temperatures higher than 100 °C, the tolerance shall be ±0,2 °C.
Dimensions in millimetres
NOTE For key, see Figure 1.
Figure 2 — DIN Ubbelohde viscometer
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SIST EN ISO 1628-1:2021
ISO 1628-1:2021(E)

5.4 Temperature-measuring device, thermometer, reading to 0,02 °C in the range in which it will be
used and in a known state of calibration, is suitable.
5.5 Timing device. Any timing device may be used providing that it can be read to 0,1 s and that its
speed is constant to 0,1 % over 15 min.
Table 1 — Ubbelohde viscometers recommended for the determination of the dilute-solution
viscosity of polymers
Viscosity/density
Nominal
ratio of solvent at Ubbelohde conforming to DIN Ubbelohde conforming to
viscometer
temperature of ISO 3105 ISO 3105
constant
measurement
Inside Inside
diameter of diameter of
Size No. a Size No. a
tube R tube R
2 −1 2 −2
mm ·s mm ·s mm mm
0,15 to 0,30 0,001 0 0,24 0 0,36
0,31 to 0,50 0,003 0C 0,36 0c 0,47
0,51 to 0,75 0,005 0B 0,46 0a 0,53
0,76 to 1,50 0,01 1 0,58 I 0,63
1,51 to 2,50 0,03 1C 0,77 Ic 0,84
2,51 to 5,00 0,05 1B 0,88 Ia 0,95
5,01 to 15,00 0,1 2 1,03 II 1,13
a
The tolerance of the inside diameter of tube R is ±2 %.
6 Solutions
6.1 Preparation
The dissolution of the test sample of polymer in the solvent shall give a “true” solution, essentially free
of microgels and associated macromolecules. Polymer degradation shall also be minimized. For these
reasons, it is necessary for the dissolution procedure to be exactly defined and it is recommended that
the following factors be specified:
a) the solvent and its pretreatment, if any;
b) the apparatus and the method of agitation;
c) the temperature range within which the system is maintained during the preparation of the
solution;
d) the time interval necessary for the complete dissolution of the polymer without degradation, or at
constant degradation;
e) the stabilizer and/or the protective atmosphere used;
f) the conditions of filtration of the solution, if applicable;
g) visual homogeneity of the solution and expected nature/composition of the filter residue.
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SIST EN ISO 1628-1:2021
ISO 1628-1:2021(E)

6.2 Concentration
Where no standard exists, careful consideration shall be given to the choice of solvent and the solution
concentration. The solution concentration shall be chosen so that the ratio of the efflux time of the
solution to the efflux time of the solvent is at least 1,2 and less than 2,0.
NOTE A lower limit of 1,2 ensures sufficient precision of the measured difference in efflux times. The upper
limit of 2,0 prevents shear effects and non-linearity of the viscosity number in relation to concentration that can
occur at higher molecular masses.
More than one concentration can therefore be used for a given polymer/solvent system, depending on
the molecular mass of the polymer under test.
3 3 3 3
The concentration is preferably expressed in kg/m of solution or as the multiple 10 kg/m , i.e. g/cm .
7 Temperature of measurement
The temperature shall be chosen with due regard to sufficient solubility and other technical
requirements, but kept constant for any particular polymer/solvent system. The temperature tolerance
shall be specified. A temperature of 25 °C ± 0,05 °C shall be chosen whenever possible. If another
temperature is used, use the temperature that was agreed between the parties concerned and stated in
the test report.
8 Procedure
8.1 General
Measure the efflux times for the solution and the solvent successively in the same viscometer, using the
procedure described in 8.2 and 8.3.
8.2 Preparing and charging the viscometer
8.2.1 Maintain the bath at the specified test temperature.
8.2.2 Charge the dry, clean viscometer (the cleaning procedure is specified in Annex A) by tilting it
about 30° from the vertical and pouring sufficient liquid through tube L (see Figure 1 or Figure 2) so that,
when the viscometer is returned to the vertical, the meniscus is between the filling marks G and H. Avoid
trapping air bubbles in the viscometer. The initial filling may be carried out away from the bath.
8.2.3 Mount the viscometer in a holder in the bath, ensuring that tube N is vertical. Allow time for the
charged viscometer to reach the temperature of the bath. Usually, 15 min will suffice if the measurement
is to be made at 25 °C. At higher temperatures, longer times is necessary. Unnecessary delays should be
avoided as it is found that the most consistent results are obtained shortly after temperature equilibrium
is attained with a freshly charged viscometer.
8.2.4 This procedure shall also be followed when a measured amount of solvent is added to a
solution, already contained in the viscometer, in order to create a more dilute solution for additional
determinations. The additional solvent shall be maintained at the specified test temperature prior to use.
8.2.5 In automated equipment, the viscometer is fixed in the vertical position within a temperature-
controlled bath and the apparatus is designed to fill the viscometer with liquid in this position. The bath
shall be maintained at the specified test temperature and an equilibration time selected in accordance
with 8.2.3.
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SIST EN ISO 1628-1:2021
ISO
...

SLOVENSKI STANDARD
oSIST prEN ISO 1628-1:2020
01-junij-2020
Polimerni materiali - Določanje viskoznosti polimerov v razredčenih raztopinah s
kapilarnimi viskozimetri - 1. del: Splošna načela (ISO/DIS 1628-1:2020)
Plastics - Determination of the viscosity of polymers in dilute solution using capillary
viscometers - Part 1: General principles (ISO/DIS 1628-1:2020)
Kunststoffe - Bestimmung der Viskosität von Polymeren in verdünnter Lösung durch ein
Kapillarviskosimeter - Teil 1: Allgemeine Grundlagen (ISO/DIS 1628-1:2020)
Plastiques - Détermination de la viscosité des polymères en solution diluée à l'aide de
viscosimètres à capillaires - Partie 1: Principes généraux (ISO/DIS 1628-1:2020)
Ta slovenski standard je istoveten z: prEN ISO 1628-1
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
oSIST prEN ISO 1628-1:2020 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 1628-1:2020

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oSIST prEN ISO 1628-1:2020
DRAFT INTERNATIONAL STANDARD
ISO/DIS 1628-1
ISO/TC 61/SC 5 Secretariat: DIN
Voting begins on: Voting terminates on:
2020-04-09 2020-07-02
Plastics — Determination of the viscosity of polymers in
dilute solution using capillary viscometers —
Part 1:
General principles
Plastiques — Détermination de la viscosité des polymères en solution diluée à l'aide de viscosimètres à
capillaires —
Partie 1: Principes généraux
ICS: 83.080.01
THIS DOCUMENT IS A DRAFT CIRCULATED
This document is circulated as received from the committee secretariat.
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
ISO/CEN PARALLEL PROCESSING
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 1628-1:2020(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
©
PROVIDE SUPPORTING DOCUMENTATION. ISO 2020

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oSIST prEN ISO 1628-1:2020
ISO/DIS 1628-1:2020(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
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Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

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oSIST prEN ISO 1628-1:2020
ISO/DIS 1628-1:2020(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Dimensions and units . 1
3.2 Definitions applicable to any liquid . 1
3.3 Definitions applicable to polymer solutions . 2
4 Principle . 4
5 Apparatus . 5
6 Solutions . 8
6.1 Preparation . 8
6.2 Concentration. 9
7 Temperature of measurement . 9
8 Procedure. 9
8.1 General . 9
8.2 Preparing and charging the viscometer . 9
8.3 Efflux time measurement (refer to Figure 1 or Figure 2) . 9
9 Expression of results .10
9.1 Reduced viscosity and intrinsic viscosity .10
9.2 K-value.11
10 Test report .11
Annex A (normative) Cleaning of apparatus .12
Annex B (normative) Notes on sources of error .13
Bibliography .16
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oSIST prEN ISO 1628-1:2020
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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).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
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.
This fourth edition cancels and replaces the third edition (ISO 1628-1:2009) as well as the Amendment 1
(2012), which have been technically revised.
The main changes compared to the previous edition are as follows:
— ISO 3205 (withdrawn) was deleted in Clause 2;
— Figure keys were revised;
— nominal viscometer constant was added to Table 1;
— in Clause 7, the last sentence was replaced with the following sentence “if another temperature is
used, use the temperature that was agreed between the parties concerned and stated in the test
report";
— editorial changes.
A list of all parts in the ISO 1628 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 © ISO 2020 – All rights reserved

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oSIST prEN ISO 1628-1:2020
DRAFT INTERNATIONAL STANDARD ISO/DIS 1628-1:2020(E)
Plastics — Determination of the viscosity of polymers in
dilute solution using capillary viscometers —
Part 1:
General principles
1 Scope
This document defines the general conditions for the determination of the reduced viscosity, intrinsic
viscosity and K‑value of organic polymers in dilute solution. It defines the standard parameters that are
applied to viscosity measurement, and can be used to develop standards for measuring the viscosities
in solution of individual types of polymer. It can also be used to measure and report the viscosities of
polymers in solution for which no separate standards exist.
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 3105:1994, Glass capillary kinematic viscometers — Specifications and operating instructions
ISO 80000-1, Quantities and units — Part 1: General
ISO 80000-4, Quantities and units — Part 4: Mechanics
3 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 http:// www .electropedia .org/
3.1 Dimensions and units
The dimensions of properties defined in this document are expressed in terms of L for length, M for
mass and T for time in accordance with ISO 80000-1, while the units appropriate to the properties are
given in ISO 80000-1 and ISO 80000-4.
3.2 Definitions applicable to any liquid
3.2.1
viscosity
viscosity of a fluid sheared between two parallel plates, one of which moves relative to the other in
uniform rectilinear motion in its own plane, defined by the Newton equation

τη= γ (1)
where
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oSIST prEN ISO 1628-1:2020
ISO/DIS 1628-1:2020(E)

t is the shear stress;
η is the viscosity;

γ
dV
is the velocity gradient or rate of shear, given by where V is the velocity of one plane
dz
relative to the other and z the coordinate perpendicular to the two planes.
−1 −1
Note 1 to entry: The dimensions of viscosity are ML T .
Note 2 to entry: The units of viscosity are Pa·s.
−3
Note 3 to entry: For practical use, the sub‑multiple 10 Pa·s is more convenient.
Note 4 to entry: Viscosity is usually taken to mean “Newtonian viscosity”, in which case the ratio of shearing
stress to velocity gradient is constant. In non‑Newtonian behaviour, which is the usual case with high‑
polymer solutions, the ratio varies with the shear rate. Such ratios are often called “apparent viscosities” at the
corresponding shear rate.
3.2.2
viscosity/density ratio
kinematic viscosity
v
ratio defined by the equation
η
v= (2)
ρ
where ρ is the density of the fluid at the temperature at which the viscosity is measured
2 −1
Note 1 to entry: The dimensions of kinematic viscosity are L T .
2 −1
Note 2 to entry: The units of kinematic viscosity are m ·s .
−6 2 −1 2 −1
Note 3 to entry: For practical use, the sub‑multiple 10 m ·s , i.e. mm ·s , is more convenient.
3.3 Definitions applicable to polymer solutions
3.3.1
relative viscosity
h
r
ratio of the viscosity of the polymer solution (of stated concentration) η and the viscosity of the pure
solvent η , at the same temperature:
0
η
η = (3)
r
η
0
Note 1 to entry: Also known as viscosity ratio.
Note 2 to entry: The ratio has no dimensions.
3.3.2
relative viscosity increment
viscosity ratio minus one:
ηη−
 
η
0
−=1 (4)
 
η η
 0  0
Note 1 to entry: Also known as viscosity ratio increment and specific viscosity.
Note 2 to entry: The increment has no dimensions.
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oSIST prEN ISO 1628-1:2020
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3.3.3
reduced viscosity
I
ratio of the viscosity ratio increment to the polymer concentration c in the solution:
ηη−
0
Ι = (5)
η c
0
Note 1 to entry: Also known as viscosity number.
3 −1
Note 2 to entry: The dimensions of reduced viscosity are L M .
3
Note 3 to entry: The units of reduced viscosity are m /kg.
−3 3 3
Note 4 to entry: For practical use, the sub‑multiple 10 m /kg, i.e. cm /g, is more convenient and the commonly
quoted numerical values for reduced viscosity (viscosity number) use these practical units.
3
Note 5 to entry: The reduced viscosity is usually determined at low concentration (less than 5 kg/m , i.e. 0,005 g/
3
cm ), except in the case of polymers of low molar mass, for which higher concentrations may be necessary.
3.3.4
inherent viscosity
ratio of the natural logarithm of the viscosity ratio to the polymer concentration in the solution:
 
η
ln
 
η
 0 
(6)
c
Note 1 to entry: Also known as logarithmic viscosity number.
Note 2 to entry: The dimensions and units are the same as those given in 3.3.3.
3
Note 3 to entry: The inherent viscosity is usually determined at low concentration (less than 5 kg/m , i.e. 0,005 g/
3
cm ), except in the case of polymers of low molar mass, for which higher concentrations may be necessary.
3.3.5
intrinsic viscosity
[h]
limiting value of the reduced viscosity or of the inherent viscosity at infinite dilution:
ηη− 0
η =lim (7)
[]
 
c→0 η0c
 
 η 
ln
 
η0
 
η =lim
[]
c→0 c
Note 1 to entry: Also known as limiting viscosity number.
Note 2 to entry: The dimensions and units are the same as those given in 3.3.3.
Note 3 to entry: The effect of the shear rate on the functions defined in 3.3.1 to 3.3.5 has been neglected, since
this effect is usually negligible for values of the reduced viscosity, inherent viscosity and intrinsic viscosity less
3 3
than 0,5 m /kg, i.e. 500 cm /g. Strictly speaking, all these functions should be defined at the limiting (preferably
infinitely small) value of the shear rate.
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oSIST prEN ISO 1628-1:2020
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3.3.6
K-value
constant, independent of the concentration of the polymer solution and peculiar to the polymer sample,
which is a measure of the average degree of polymerization:
Kk-value=1000 (8)
[2]
Note 1 to entry: According to H. Fikentscher, k is calculated as follows:
2
 75k 
lgη = +kc100
 
r
1+150kc
 
and therefore
2
 
15,,lgηη−+11++21+ 51lg ,5lgη
 
rr r
c
 
k= (9)
150+300c
where
η is the viscosity ratio (see 3.3.1);
η =
r
η
0
3 3 3
c is the concentration, in 10 kg/m , i.e. g/cm .
Note 2 to entry: A limiting viscosity number [η] can be calculated from k:
k
2
    []η =+230,375kk
()
k
4 Principle
The data needed for the evaluation of the functions defined in 3.3 are obtained by means of a capillary‑
tube viscometer. The efflux times of a given volume of solvent t and of solution t are measured at fixed
0
temperature and atmospheric‑pressure conditions in the same viscometer. The efflux time of a liquid is
related to its viscosity by the Poiseuille‑Hagenbach‑Couette equation:
η A
 
vC== t− (10)
 
2
ρ
t 
where
v is the viscosity/density ratio (see 3.2.2);
C is a constant of the viscometer;
A is a parameter of the kinetic‑energy correction;
ρ is the density of the liquid;
t is the efflux time.
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A
 
For the purposes of this document, the kinetic energy correction shall be regarded as negligible
 
2
t 
when it is less than 3 % of the viscosity of the solvent. Hence Equation (10) can be reduced to
η
vC== t (11)
ρ
Moreover, if the solution concentrations are limited so that the solvent density ρ0 and that of the
η
solution ρ differ by less than 0,5 %, the viscosity ratio will be given by the so‑called “efflux time
η
0
t
ratio” .
t
0
The need for these constraints, and the consequences of not observing them, is developed in Annex B.
5 Apparatus
5.1 Capillary viscometer, of the suspended‑level Ubbelohde type.
The use of a viscometer having the dimensions given in Figure 1 or Figure 2 is strongly recommended.
Furthermore, it is strongly recommended that the size of the viscometer be chosen from among
those listed in Table 1. The choice is determined by the viscosity/density ratio of the solvent at the
temperature of the measurement, as indicated in Table 1. The next‑smaller viscometer can also be used.
Other types of viscometer listed in ISO 3105 can be used, provided they give results equivalent to those
given by the particular size of Ubbelohde viscometer chosen on the basis of the criteria specified in the
preceding paragraph. In cases of dispute, an Ubbelohde viscometer shall be used.
With automated apparatus, fitted with special timing devices, it may be possible to obtain equivalent
results with larger sizes of capillary than those listed for the appropriate solvent viscosity/density ratio
in Table 1.
5.2 Viscometer holder, suitable to hold the viscometer firmly in the thermostatic bath (5.3) in the
vertical position.
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oSIST prEN ISO 1628-1:2020
ISO/DIS 1628-1:2020(E)

Dimensions in millimetres
Key
A lower reservoir L mounting tube
B suspended level bulb M lower vent tube
C timing bulb N upper vent tube
D upper reservoir P connecting tube
E and F timing marks R working capillary
G and H filling marks
a
internal diameter
Figure 1 — Ubbelohde viscometer
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oSIST prEN ISO 1628-1:2020
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5.3 Thermostatic bath, holding a transparent liquid or vapour and of such depth that, during the
measurement, no portion of the test liquid will be less than 20 mm below the surface of the bath medium
or less than 20 mm above the bottom of the bath.
The temperature control shall be such that, within the range 25 °C to 100 °C, the temperature of the bath
does
...

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