EN ISO 1628-2:1998

Plastics - Determination of the viscosity of polymers in dilute solution using capillary viscometers - Part 2: Poly(vinyl chloride) resins (ISO 1628-2:1998)

Kunststoffe - Bestimmung der Viskosität von Polymeren in verdünnter Lösung unter Verwendung von Kapillarviskosimetern - Teil 2: Vinylchlorid-Polymere (ISO 1628-2:1998)

Dieser Teil von ISO 1628 definiert Bedingungen zur Bestimmung der reduzierten Viskosität (auch bekannt unter dem Begriff Viskositätszahl) und des K-Wertes von VC-Polymeren. Er findet Anwendung für Polymere in pulvriger Form, die aus Homopolymeren des Monomers Vinylchlorid und Co- oder Terpolymeren etc. von Vinylchlorid mit einem oder mehreren anderen Monomeren bestehen, wobei aber Vinylchlorid den Hauptbestandteil darstellt. Die Polymere können kleine Mengen nicht polymerisierter Substanzen (z.B. Emulgatoren oder Suspensionshilfsmittel, Katalysatorreste etc.) sowie anderer Substanzen enthalten.

Polimerni materiali - Določanje viskoznosti polimerov v razredčenih raztopinah s kapilarnimi viskozimetri - 2. del: Polivinilklorid (ISO 1628-2:1998)

General Information

• Status: Withdrawn
• Publication Date: 30-Nov-1998
• Withdrawal Date: 14-Jul-2020
• ICS: 83.080 - Plastics
• Technical Committee: CEN/TC 249 - Plastics
• Drafting Committee: CEN/TC 249/SC 1/WG 8 - Polyvinyls
• Current Stage: 9960 - Withdrawal effective - Withdrawal
• Completion Date: 15-Jul-2020
• Ref Project: SIST EN ISO 1628-2:2000 - Plastics - Determination of the viscosity of polymers in dilute solution using capillary viscometers - Part 2: Poly(vinyl chloride) resins (ISO 1628-2:1998)

Relations

• Replaced By: EN 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)
• Effective Date: 21-Jan-2020

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2000
3ROLPHUQLPDWHULDOL'RORþDQMHYLVNR]QRVWLSROLPHURYYUD]UHGþHQLKUD]WRSLQDKV
NDSLODUQLPLYLVNR]LPHWULGHO3ROLYLQLONORULG,62
Plastics - Determination of the viscosity of polymers in dilute solution using capillary
viscometers - Part 2: Poly(vinyl chloride) resins (ISO 1628-2:1998)
Kunststoffe - Bestimmung der Viskosität von Polymeren in verdünnter Lösung unter
Verwendung von Kapillarviskosimetern - Teil 2: Vinylchlorid-Polymere (ISO 1628-2:1998)
Ta slovenski standard je istoveten z: EN ISO 1628-2:1998
ICS:
83.080.20 Plastomeri Thermoplastic materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL ISO
STANDARD 1628-2
Second edition
1998-12-01
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)
A
Reference number
ISO 1628-2:1998(E)
ISO 1628-2:1998(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.
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.
International Standard ISO 1628-2 was prepared by Technical Committee
ISO/TC 61, Plastics, Subcommittee 9, Thermoplastic materials.
This second edition cancels and replaces the first edition
(ISO 1628-2:1988) which has been modified to include:
— the determination of the K-value;
— a limit on the volatile-matter content of resins that can be tested using
this part of ISO 1628;
— revised viscometer specifications;
— a reference viscometer;
— a precision statement.
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
©  ISO 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet  [e-mail]
Printed in Switzerland
ii
©
ISO ISO 1628-2:1998(E)
— 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
iii
©
INTERNATIONAL STANDARD  ISO ISO 1628-2:1998(E)
Determination of the viscosity of polymers in dilute solution using
capillary viscometers —
Part 2:
Poly(vinyl chloride) resins
1  Scope
This part of ISO 1628 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 part of ISO 1628 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.
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 may not have the same molecular mass.
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 part of ISO 1628 will only give values for reduced viscosity and K-value that are comparable when the
concentrations of the solutions used are identical.
Limiting viscosity number is not used for PVC resins.
The experimental procedures described in this part of ISO 1628 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 may 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 standards contain provisions which, through reference in this text, constitute provisions of this part of
ISO 1628. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties
to agreements based on this part of ISO 1628 are encouraged to investigate the possibility of applying the most recent
editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International
Standards.
ISO 1042:1998, Laboratory glassware — One-mark volumetric flasks.
©
ISO 1628-2:1998(E) ISO
ISO 1269:1980, Plastics — Homopolymer and copolymer resins of vinyl chloride — Determination of volatile matter
(including water).
ISO 1628-1:1998, Plastics — Determination of the viscosity of polymers in dilute solution using capillary viscom-
eters — Part 1: General principles.
ISO 3105:1994, Glass capillary kinematic viscometers — Specifications and operating instructions.
3  Definitions
The terms used in this part of ISO 1628 are defined in ISO 1628-1:1998, clause 3, and, in particular, definitions 3.3.3
(reduced viscosity) and 3.3.6 (K-value).
4  Principle
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 and
–6 2 –1 2 –1 2 –1
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
The apparatus required to carry out viscosity measurements on polymers in dilute solution is described in
ISO 1628-1:1998, clause 5. In addition, the following particular items are required for the procedures described in
this part of ISO 1628:
6.1 Viscometer: From the viscometers described in subclause 5.1 of ISO 1628-1:1998, model 1C, with a capillary
diameter of 0,77 mm – 2 %, from table B.4 of ISO 3105:1994, 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.
6.2 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.
6.3 Filter funnel, with fritted-glass filter disc of medium porosity (pore size 40 μm to 50 μm), or glass funnel with
paper filter.
6.4 Mechanical agitator, equipped with a heating device to keep the flask (6.2) 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.
6.5 Analytical balance, accurate to 0,1 mg.
©
ISO ISO 1628-2:1998(E)
6.6 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.
6.7 Thermometer, with a sensitivity of 0,05 °C.
6.8 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 1628-1:1998, clause 6.
Prepare a solution with a concentration of 5 g/l – 0,1 g/l 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 (6.2). 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 (6.4). 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 1 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 will require the amounts of solvent and test portion taken to be
determined by experiment, and may 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 subclause 6.2 of
ISO 1628-1:1998. 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.
©
ISO 1628-2:1998(E) ISO
9.2  Determination of efflux times
The procedure is described in ISO 1628-1:1998, clause 8.
The temperature of the thermostat (see 6.6) shall be set such that the actual temperature which is measured by the
thermometer (6.7) 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 6.3).
Particular care shall be taken over viscometer cleaning, which shall be based on the procedure described in
ISO 1628-1:1998, 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 part of ISO 1628 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 for each test portion as specified in ISO 1628-1:1998, clause 9, using the equation
I
tt−
I=
tc
where
t and t are the efflux times, in seconds, of the solution and solvent, respectively;
c is the concentration of the solution, in grams per millilitre.
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.
If the solution concentration is 5 g/l – 0,005 g/l, it is more convenient to read off the values of I from table 1,
3 –3
expressing I in (m /kg) · 10 , i.e. ml/g, rounded to the first place of decimals.
10.2  K-value
For each test portion, calculate the K-value as specified in ISO 1628-1:1998, clause 9, using the equation
 
15,loghh−+1 1+  +21+ ,l5og 1,l5ogh
rrr
 
c
K = × 1000
150+ 300 c
where
SIST EN ISO 1628-
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