SIST EN ISO 1628-2:2020

SLOVENSKI STANDARD
01-oktober-2020
Nadomešča:
SIST EN ISO 1628-2:2000
Polimerni materiali - Določanje viskoznosti polimerov v razredčenih raztopinah s
kapilarnimi viskozimetri - 2. del: Polivinilklorid (ISO 1628-2:2020)
Plastics - Determination of the viscosity of polymers in dilute solution using capillary
viscometers - Part 2: Poly(vinyl chloride) resins (ISO 1628-2:2020)
Kunststoffe - Bestimmung der Viskosität von Polymeren in verdünnter Lösung unter
Verwendung von Kapillarviskosimetern - Teil 2: Vinylchlorid-Polymere (ISO 1628-2:2020)
Plastiques - Détermination de la viscosité des polymères en solution diluée à l'aide de
viscosimètres à capillaires - Partie 2: Résines de poly (chlorure de vinyle) (ISO 1628-
2:2020)
Ta slovenski standard je istoveten z: EN ISO 1628-2:2020
ICS:
83.080.20 Plastomeri Thermoplastic materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 1628-2
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2020
EUROPÄISCHE NORM
ICS 83.080.20 Supersedes EN ISO 1628-2:1998
English Version
Plastics - Determination of the viscosity of polymers in
dilute solution using capillary viscometers - Part 2:
Poly(vinyl chloride) resins (ISO 1628-2:2020)
Plastiques - Détermination de la viscosité des Kunststoffe - Bestimmung der Viskosität von
polymères en solution diluée à l'aide de viscosimètres Polymeren in verdünnter Lösung unter Verwendung
à capillaires - Partie 2: Résines de poly(chlorure de von Kapillarviskosimetern - Teil 2: Vinylchlorid-
vinyle) (ISO 1628-2:2020) Polymere (ISO 1628-2:2020)
This European Standard was approved by CEN on 9 June 2020.

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
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 1628-2:2020 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 1628-2:2020) 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 January 2021, and conflicting national standards shall
be withdrawn at the latest by January 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 1628-2:1998.
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 1628-2:2020 has been approved by CEN as EN ISO 1628-2:2020 without any
modification.
INTERNATIONAL ISO
STANDARD 1628-2
Third edition
2020-06
Plastics — Determination of the
viscosity of polymers in dilute solution
using capillary viscometers —
Part 2:
Poly(vinyl chloride) resins
Plastiques — Détermination de la viscosité des polymères en solution
diluée à l'aide de viscosimètres à capillaires —
Partie 2: Résines de poly(chlorure de vinyle)
Reference number
ISO 1628-2:2020(E)
©
ISO 2020
ISO 1628-2:2020(E)
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO 2020 – All rights reserved

ISO 1628-2:2020(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Principle . 2
5 Materials . 2
6 Apparatus . 2
7 Sampling . 3
8 Number of determinations . 3
9 Procedure. 3
9.1 Preparation of solution . 3
9.2 Determination of efflux times . 3
10 Expression of results . 4
10.1 Reduced viscosity . 4
10.2 K-value. 4
11 Precision . 5
12 Test report . 5
Annex A (informative) Conversion of viscosity ratio (VR) to reduced viscosity (I) and K-value .6
Bibliography .15
ISO 1628-2:2020(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 9,
Thermoplastic materials, 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 ISO 1628-2:1998, of which it constitutes a minor revision.
The change compared to the previous edition is as follows:
— Clause 2 has been updated;
— the former Table 1 has been moved to the new informative Annex A.
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

INTERNATIONAL STANDARD ISO 1628-2:2020(E)
Plastics — Determination of the viscosity of polymers in
dilute solution using capillary viscometers —
Part 2:
Poly(vinyl chloride) resins
1 Scope
1.1 This document specifies conditions for the determination of the reduced viscosity (also known
as viscosity number) and K-value of PVC resins. It is applicable to resins in powder form which consist
of homopolymers of the monomer vinyl chloride and copolymers, terpolymers, etc., of vinyl chloride
with one or more other monomers, but where vinyl chloride is the main constituent. The resins may
contain small amounts of unpolymerized substances (e.g. emulsifying or suspending agents, catalyst
residues, etc.) and other substances added during the course of the polymerization. This document
is not applicable, however, to resins having a volatile-matter content in excess of 0,5 % ± 0,1 %, when
determined in accordance with ISO 1269. In addition to this, it is not applicable to resins which are not
entirely soluble in cyclohexanone.
1.2 The reduced viscosity and K-value of a particular resin are related to its molecular mass, but the
relationship varies depending on the concentration and type(s) of other monomer(s) present. Hence,
homopolymers and copolymers having the same reduced viscosity or K-value might not have the same
molecular mass.
1.3 The values determined for reduced viscosity and K-value, for a particular sample of PVC resin, are
influenced differently by the concentration of the solution chosen for the determination. Hence the use
of the procedures described in this document only gives values for reduced viscosity and K-value that are
comparable when the concentrations of the solutions used are identical.
1.4 Limiting viscosity number is not used for PVC resins.
1.5 The experimental procedures described in this document can also be used to characterize the
polymeric fraction obtained during the chemical analysis of a PVC composition. However, the values
calculated for the reduced viscosity and K-value in these circumstances might not indicate the actual
values for the resin used to produce the composition because of the impure nature of the recovered
polymer fraction.
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 1042, Laboratory glassware — One-mark volumetric flasks
ISO 1628-1:2009, 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
ISO 1628-2:2020(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 1628-1 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/
4 Principle
4.1 A test portion is dissolved in a solvent. The reduced viscosity and the K-value are calculated from
the efflux times for the solvent and the solution in a capillary tube viscometer.
5 Materials
−6 2 –1
5.1 Cyclohexanone, having a viscosity/density ratio (kinematic viscosity) between 2,06 × 10 m s
−6 2 –1 2 –1 2 –1
and 2,33 × 10 m s (2,06 mm s and 2,33 mm s ) at 25 °C. The specified boiling point shall be
155 °C. Store the solvent in the dark in a dark-coloured bottle fitted with a ground-glass stopper. Check
the kinematic viscosity before use.
6 Apparatus
6.1 The apparatus required to carry out viscosity measurements on polymers in dilute solution are in
accordance with ISO 1628-1:2009, Clause 5. In addition, the following particular items are required for
the procedures described in this document.
6.2 Viscometer. From the viscometers described in ISO 1628-1:2009, 5.1, model 1C, with a capillary
diameter of 0,77 (1 ± 2 %) mm, from ISO 3105:1994, Table B.4, shall be used as the reference viscometer.
Other viscometers described in ISO 1628-1 may be used provided the correlation between the chosen
viscometer and the reference viscometer has been established over the range of reduced viscosities and
K-values to be measured, and the results are corrected accordingly.
6.3 Graduated flask (one-mark volumetric flask), class A, as specified in ISO 1042, with a volume
of 50 ml.
NOTE The use of a flask calibrated at a temperature of 20 °C, as specified in ISO 1042, causes a systematic
error which can, however, be neglected.
6.4 Filter funnel, with fritted-glass filter disc of medium porosity (pore size 40 µm to 50 µm), or glass
funnel with paper filter.
6.5 Mechanical agitator, equipped with a heating device to keep the flask (6.3) and its contents at a
temperature between 80 °C and 85 °C.
As an alternative, a rotary agitator or shaker may be placed in an oven at a temperature between 80 °C
and 85 °C.
6.6 Analytical balance, accurate to 0,1 mg.
6.7 Temperature-regulated bath, capable of being set at 25,0 °C ± 0,5 °C in steps of 0,1 °C and
maintaining a stability of ± 0,05 °C around the set temperature.
2 © ISO 2020 – All rights reserved

ISO 1628-2:2020(E)
6.8 Thermometer, with a sensitivity of 0,05 °C.
6.9 Time-measuring device, with a sensitivity of 0,1 s.
7 Sampling
Take a sample which is representative of the resin whose properties are to be determined and large
enough for at least two determinations.
8 Number of determinations
Carry out two complete determinations, starting each with a fresh test portion.
9 Procedure
9.1 Preparation of solution
General requirements for the dissolution of polymer in solvent are given in ISO 1628-1:2009, Clause 6.
3 3
Prepare a solution with a concentration of 5 kg/m ± 0,1 kg/ m at 25 °C ± 1 °C, as follows.
Weigh, to the nearest 0,2 mg, 0,250 g ± 0,005 g of resin and transfer it quantitatively to the 50 ml
flask (6.3). Add about 40 ml of cyclohexanone (5.1) to the flask, swirling the flask by hand to prevent
coagulation or the formation of lumps. Continue dissolution by agitating for 1 h between 80 °C and
85 °C using the agitator (6.5). Check visually that dissolution is complete. If gelatinized particles are
still visible, start again with a new portion of the resin. Cool the solution to 25 °C ± 1 °C and make up to
the mark with cyclohexanone at the same temperature. Mix the solution thoroughly by shaking.
Determine the actual concentration of the solution to an accuracy of ± 0,1 %.
If a mass of 0,250 g ± 0,000 25 g is taken and made up to 50 ml of solution as described above, Table A.1
in Annex A can be used to read off the reduced viscosity and K-value from the ratio of the efflux time of
the solution to that of the solvent (the so-called viscosity ratio).
Alternative methods for the preparation of the solution may be used, for example the addition of a
measured volume of solvent to a measured mass of test portion, provided that the values obtained for
the reduced viscosity and K-value can be shown to be equivalent to those obtained with the method
of solution preparation described above. Such alternative methods of solution preparation requires
the amounts of solvent and test portion taken to be determined by experiment, and can also require
compensation for loss of solvent by evaporation during the dissolution process.
With resins having K-values greater than 85, the ratio of the efflux time of the solution to that of
the solvent will exceed the maximum value of 2,0, which is contrary to the requirement specified in
ISO 1628-1:2009, 6.2. In order to ensure uniformity of testing for PVC, this non-conformity shall be
ignored, and all currently available resins tested using the same test-portion mass.
9.2 Determination of efflux times
The procedure is described in ISO 1628-1:2009, Clause 8.
The temperature of the thermostat (6.7) shall be set such that the actual temperature which is measured
by the thermometer (6.8) lies in the range 25 °C ± 0,5 °C. The measured temperature shall be stable to
±0,05 °C around the temperature at which the thermostat has been set.
When filling the viscometer, filter the solvent and the solution using a filter funnel or a glass funnel and
paper filter (see 6.4).
ISO 1628-2:2020(E)
Particular care shall be taken over viscometer cleaning, which shall be based on the procedure described
in ISO 1628-1:2009, Annex A. Efflux times with the control solvent cyclohexanone shall remain constant
to within 0,2 s for a given viscometer. With the solution, repeat the measurement of the efflux time until
two successive measurements differ by less than 0,25 %. Always discard the first efflux time reading.
NOTE This is a manual procedure. Proprietary equipment is available which will organize the charging of
the viscometer with solution and solvent and measure the respective efflux times automatically. The use of such
equipment is included in the scope of this document provided that all the procedures and verification checks
described above are followed by the automated procedure.
10 Expression of results
10.1 Reduced viscosity
Calculate the reduced viscosity, I, for each test portion as specified in ISO 1628-1:2009, Clause 9, using
Formula (1):
tt−
I= (1)
tc
where
t and t are the efflux times, in seconds, of the solution and solvent, respectively;
3 3 3
c is the concentration of the solution, in 10 kg/m , i.e. g/cm .
Calculate the reduced viscosity I for the sample as the mean value of the two individual values obtained
in the two determinations, expressing the result to the nearest whole number. If the I values obtained
in the two determinations deviate by more than ± 0,4 % from the mean value, these results shall be
rejected and further determinations carried out with fresh test portions.
3 3
If the solution concentration is 5 kg/m ± 0,005 kg/m , it is more convenient to read off the values of I
3 −3 3
from Table A.1, expressing I in (m /kg) · 10 , i.e. cm /g, rounded to the first place of decimals.
10.2 K-value
For each test portion, calculate the K-value as specified in ISO 1628-1:2009, Clause 9, using Formula (2):
 
15,lg,ηη−+11++21+ 51lg ,l5 gη
 
rr r
c
 
K = ×1000 (2)
150+300c
where
η t
is the ratio of the viscosities (efflux times) of the solution and solvent;
η ==
r
η t
t and t are the efflux times, in seconds, of the solution and solvent, respectively;
3 3 3
c is the concentration of the solution, in 10 kg/m , i.e. g/cm .
Calculate the K-value for the sample as the mean value of the two individual K-values obtained in the
two determinations, expressing the result to the first place of decimals. If the K-values obtained in the
two determinations deviate by more than ± 0,4 % from the mean value, these results shall be rejected
and further determinations carried out with fresh test portions.
3 3
If the solution concentration is 5 kg/m ± 0,005 kg/m , it is more convenient to read off the K-value
from Table A.1, rounding to the second place of decimals.
4 © ISO 2020 – All rights reserved

ISO 1628-2:2020(E)
11 Precision
Interlaboratory trials were conducted on three resins in 11 laboratories on four different dates. These
interlaboratory trials gave the following results for the repeatability standard deviation s (within the
r
same laboratory) and the reproducibility standard deviation s (among different laboratories).
R
See Table 1.
Table 1 — Results for s , s of K-value and reduced viscosity
r R
K-value Reduced viscosity
Approximately Approximately Approximately Approximately Approximately Approximately
50 70 90 61 124 227
s 0,132 0,115 0,120 0,313 0,458 0,742
r
s 0,420 0,291 0,495 0,984 1,202 3,042
R
12 Test report
The test report shall include the following information:
a) a reference to this document, i.e. ISO 1628-2:2020;
b) all details necessary for complete identification of the material under test;
c) the reduced viscosity and/or K-value of the resin sample;
d) any difference
...