SIST EN ISO 1628-1:2000

SLOVENSKI STANDARD
SIST EN ISO 1628-1:2000
01-maj-2000
3ROLPHUQLPDWHULDOL'RORþDQMHYLVNR]QRVWLSROLPHURYYUD]UHGþHQLKUD]WRSLQDKV
NDSLODUQLPLYLVNR]LPHWULGHO6SORãQDQDþHOD,62
Plastics - Determination of the viscosity of polymers in dilute solution using capillary
viscometers - Part 1: General principles (ISO 1628-1:1998)
Kunststoffe - Bestimmung der Viskosität von Polymeren in verdünnter Lösung durch ein
Kapillarviskosimeter - Teil 1: Allgemeine Grundlagen (ISO 1628-1:1998)
Plastiques - Détermination de la viscosité des polymeres en solution diluée a l'aide de
viscosimetres a capillaires - Partie 1: Principes généraux (ISO 1628-1:1998)
Ta slovenski standard je istoveten z: EN ISO 1628-1:1998
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST EN ISO 1628-1:2000 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 1628-1:2000

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SIST EN ISO 1628-1:2000

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SIST EN ISO 1628-1:2000

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SIST EN ISO 1628-1:2000
INTERNATIONAL ISO
STANDARD 1628-1
Second edition
1998-09-15
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
A
Reference number
ISO 1628-1:1998(E)

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SIST EN ISO 1628-1:2000
ISO 1628-1:1998(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 1628-1 was prepared by Technical Committee
ISO/TC 61, Plastics, Subcommittee SC 5, Physical-chemical properties.
This second edition cancels and replaces the first edition (ISO 1628-1:
1984), which has been revised to include
a) the determination of the K-value;
b) a procedure for the determination of the efflux times for several
solution concentrations by the addition of solvent to a given solution
held in the viscometer;
c) revised viscometer specifications.
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
©  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 iso@iso.ch
Printed in Switzerland
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SIST EN ISO 1628-1:2000
©
ISO ISO 1628-1:1998(E)
—  Part 4: Polycarbonate (PC) moulding and extrusion materials
—  Part 5: Thermoplastic polyester (TP) homopolymers and copolymers
—  Part 6: Methyl methacrylate polymers
Annexes A and B form an integral part of this part of ISO 1628. Annex C is
for information only.
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SIST EN ISO 1628-1:2000

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SIST EN ISO 1628-1:2000
©
INTERNATIONAL STANDARD  ISO ISO 1628-1:1998(E)
Plastics — Determination of the viscosity of polymers in dilute
solution using capillary viscometers —
Part 1:
General principles
1  Scope
This part of ISO 1628 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 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 31-0:1992, Quantities and units — Part 0: General principles.
ISO 31-3:1992, Quantities and units — Part 3: Mechanics.
ISO 3105:1994, Glass capillary kinematic viscometers — Specifications and operating instructions.
ISO 3205:1976, Preferred test temperatures.
3  Definitions
3.1  Dimensions and units
The dimensions of properties defined in this part of ISO 1628 are expressed in terms of L for length, M for mass and
T for time in accordance with ISO 31-0, while the units appropriate to the properties are given in ISO 31-0 and
ISO 31-3.
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ISO 1628-1:1998(E)
3.2  Definitions applicable to any liquid
3.2.1  viscosity: The 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, is defined by the Newton equation
•
th= g .(1)
where
is the shear stress;
t
is the viscosity;
η
dV
•
is the velocity gradient or rate of shear, given by where V is the velocity of one plane relative
g
dz
to the other and z the coordinate perpendicular to the two planes.
-1 -1
The dimensions of viscosity are: ML T .
.
The units of viscosity are: Pa s.
-3 .
For practical use, the sub-multiple 10 Pa s is more convenient.
NOTE —  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: This ratio is defined by the equation
h
v = .(2)
r
where r is the density of the fluid at the temperature at which the viscosity is measured.
2 -1
The dimensions of kinematic viscosity are: L T .
2.
-1
The units of kinematic viscosity are m s .
-6 2. -1 2. -1
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 (also known as viscosity ratio): The ratio of the viscosity of the polymer solution (of
r
stated concentration) h and the viscosity of the pure solvent h , at the same temperature:
0
h
h =
...(3)
r
h
0
The ratio has no dimensions.
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3.3.2  relative viscosity increment (also known as viscosity ratio increment and specific viscosity): The viscosity
ratio minus one:
 h hh−
0
−=1 .(4)
 
 h h
0
0
The increment has no dimensions.
3.3.3  reduced viscosity, I (also known as viscosity number): The ratio of the viscosity ratio increment to the
polymer concentration c in the solution:
hh−
0
I = .(5)
h c
0
3 -1
The dimensions of reduced viscosity are: L M .
3
The units of reduced viscosity are m /kg.
-3 3 3
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 3
The reduced viscosity is usually determined at low concentration (less than 5 kg/m , i.e. 0,005 g/cm ), except in the
case of polymers of low molar mass, for which higher concentrations may be necessary.
3.3.4  inherent viscosity (also known as logarithmic viscosity number): The ratio of the natural logarithm of the
viscosity ratio to the polymer concentration in the solution:
 
h
 
ln
 
h
 
0
...(6)
c
The dimensions and units are the same as those given in 3.3.3.
3 3
The inherent viscosity is usually determined at low concentration (less than 5 kg/m , i.e. 0,005 g/cm ), except in the
case of polymers of low molar mass, for which higher concentrations may be necessary.
3.3.5  intrinsic viscosity, [h] (also known as limiting viscosity number): The limiting value of the reduced viscosity
or of the inherent viscosity at infinite dilution:
hh− 
0
h= lim
[]
 
c→0h c
0
...(7)
h
ln
 
h
0
h=  lim
[]
→0 c
c
The dimensions and units are the same as those given in 3.3.3.
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NOTE —  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
3 3
negligible for values of the reduced viscosity, inherent viscosity and intrinsic viscosity less 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.
3.3.6  K-value: A constant independent of the concentration of the polymer solution and peculiar to the polymer
sample. It is a measure of the average degree of polymerization.
K-value = 1 000 k .(8)
[ ]
2
According to H. Fikentscher , k is calculated as follows:
2
 
75 k
 
lg h = +kc100
r
 
1+150 kc
 
and therefore
2
 
15,,lghh−+1 1+ +21+ 5 lg 1,5 lgh
rrr
 
c
k = .(9)
150+ 300 c
where
h
h = = the viscosity ratio (see 3.3.1);
r
h
0
3 3 3
c is the concentration, in 10 kg/m , i.e. g/cm .
A limiting viscosity number [η] can be calculated from k:
k
2
h=+230,3 75kk
[]
()
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 and of solution are measured at fixed temperature and
t t
0
atmospheric-pressure conditions in the same viscometer. The efflux time of a liquid is related to its viscosity by the
Poiseuille-Hagenbach-Couette equation:
h A
 
vk==t− .(10)
 
2
 
r
t
where
v is the viscosity/density ratio (see 3.2.2);
k 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 part of ISO 1628, the kinetic energy correction shall be regarded as negligible when it
 
2
 
t
is less than 3 % of the viscosity of the solvent. Hence equation (10) can be reduced to
h
vk==t .(11)
r
Moreover, if the solution concentrations are limited so that the solvent density r and that of the solution r differ by
0
h t
less than 0,5 %, the viscosity ratio will be given by the so-called “efflux time ratio” .
t
h
0
0
The need for these constraints, and the consequences of not observing them, is developed in annex B.
5 Apparatus
5.1  Capillary viscometer, suspended-level Ubbelohde type.
The use of a viscometer having the dimensions given in figure 1 or 2 is strongly recommended. Furthermore, it is
strongly recommended that the size of the viscometer is 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.
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 not
vary from the specified temperature by more than 0,05 °C 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.
5.4  Temperature-measuring device.
A liquid-in-glass, “total immersion” thermometer, reading to 0,05 °C in the range to be used and in a known state of
calibration, is suitable. Other thermometric devices of at least equal precision may be used.
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.
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Dimensions in millimetres
Graduation marks: E and F
Filling marks: G and H
Figure 1 — Ubbelohde viscometer
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Dimensions in millimetres
Graduation marks: E and F
Filling marks: G and H
Figure 2 — DIN Ubbelohde viscometer
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Table 1 — Ubbelohde viscometers recommended for the determination of
the dilute-solution viscosity of polymers
Viscosity/density Ubbelohde conforming to DIN Ubbelohde conforming to
ratio of solvent at ISO 3105:1994, table B.4 ISO 3105:1994, table B.9
temperature of
measurement
Diameter of Diameter of
Size No.
Size No.
capillary capillary
2. -1
mm s
mm (± 2 %) mm (± 2 %)
0,15 to  0,30 0 0,24 0 0,36
0,31 to  0,50 0C 0,36 0c 0,47
0,51 to  0,75 0B 0,46 0a 0,53
0,76 to  1,50 1 0,58 I 0,63
1,51 to  2,50 1C 0,77 Ic 0,84
2,51 to  5,00 1B 0,88 Ia 0,95
5,01 to 15,00 2 1,03 II 1,13
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.
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 is necessary to ensure sufficient precision of the measured difference in efflux times. The upper
limit of 2,0 is necessary because, at higher molecular masses, there can be shear effects and non-linearity of the viscosity
number in relation to concentration.
More than one concentration can therefore be used for a given polymer/solvent system, depending on the molecular
mass of the polymer under test.
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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, it shall be chosen from the
values recommended in ISO 3205 and state
...