ISO 16152:2005

INTERNATIONAL ISO
STANDARD 16152
First edition
2005-07-01


Plastics — Determination of xylene-
soluble matter in polypropylene
Plastiques — Détermination des matières présentes dans le
polypropylène solubles dans le xylène





Reference number
ISO 16152:2005(E)
©
ISO 2005

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ISO 16152:2005(E)
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ii © ISO 2005 – All rights reserved

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ISO 16152:2005(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Terms and definitions. 1
3 Apparatus . 1
4 Reagents. 2
5 Procedure . 2
5.1 Preparation of the xylene. 2
5.2 Determination of level of impurities in the xylene (solvent blank) . 2
5.3 Determination of percentage xylene-soluble matter in the polypropylene . 3
6 Calculations. 6
7 Precision and bias . 6
8 Test report . 7

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ISO 16152:2005(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 16152 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 9, Thermoplastic
materials.
It replaces ISO 6427:1992, Annex B, which has been technically revised. The revised method tightens the
physical parameters of the test to provide improved repeatability and reproducibility.
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ISO 16152:2005(E)
Introduction
This International Standard specifies a method for the quantitative determination of those components of
polypropylene that are soluble in xylene. This new method defines more precisely the factors that have the
greatest influence on the repeatability and reproducibility of the determination. The polypropylene is dissolved
in hot xylene, then cooled under controlled conditions down to 25 °C, which results in the precipitation of the
insoluble fraction. The soluble matter remains in the xylene. The xylene is then evaporated and the residue
weighed. The solubles content of polypropylene is important as it has a major influence on the properties of
the polypropylene.

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INTERNATIONAL STANDARD ISO 16152:2005(E)

Plastics — Determination of xylene-soluble matter
in polypropylene
1 Scope
1.1 This International Standard specifies a method for determining the mass fraction of a polypropylene
homopolymer or copolymer which is soluble in xylene at 25 °C.
1.2 A weighed amount of dried sample is dissolved in xylene under reflux conditions, then cooled under
controlled conditions and maintained at 25 °C to ensure controlled crystallization of the insoluble fraction.
1.3 The xylene-soluble fraction is then recovered by evaporation of the xylene and determined by weighing
the residue.
1.4 Other materials with solubilities similar to that of the xylene-soluble fraction, such as additives, may
interfere with the determination.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
xylene-soluble fraction
S
s
that percentage, by mass, of the polymer that does not precipitate out when a solution of the polymer in
xylene is cooled from reflux temperature to +25 °C and held at that temperature for a specified period of time
3 Apparatus
3.1 Reflux condenser, length 400 mm.
3.2 Flat-bottomed flask, capacity 400 ml, with one or two necks, or conical flask or cylindrical bottle of
similar capacity.
3.3 Insulating disc, made of fibreglass or mineral wool.
3.4 Magnetic stirrer, with temperature-controlled hotplate, thermostatted oil bath or heating block capable
of maintaining 140 °C to 150 °C.
3.5 Stirrer bar.
3.6 Pipette, class A, 200 ml or equivalent.
3.7 Pipette, class A, 100 ml or equivalent.
3.8 Glass-stoppered flask, 250 ml.
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ISO 16152:2005(E)
3.9 Thermostatically controlled water bath, with sufficient cooling capacity to maintain a constant bath
temperature of 25 °C ± 0,5 °C while cooling down the flask containing the xylene/polymer solution (see 5.3.8
and 5.3.9).
3.10 Filter paper, fluted, Whatman No. 4, No. 541 or equivalent, at least 125 mm in diameter.
3.11 Funnel, 60°, or equivalent, at least 125 mm in diameter.
3.12 Vacuum oven.
3.13 Disposable aluminium pans, 300 ml capacity, with smooth sides.
3.14 Temperature-controlled hotplate.
3.15 Analytical balance, with a minimum weighing sensitivity of 0,1 mg (a sensitivity of 0,01 mg is preferred).
3.16 Desiccator, containing an appropriate desiccant.
3.17 Timer, preferably with an alarm, reading in minutes.
3.18 Oven, conventional forced-air or gravity-convection type.
4 Reagents
4.1 Reagent-grade ortho-xylene (o-xylene), assay by gas chromatography (GC) 98 % min.; ethylbenzene
content as determined by GC less than 2 %; evaporation residue at 140 °C less than 0,002 g/100 ml; boiling
point 144 °C.
or
4.2 Reagent-grade para-xylene (p-xylene), assay by gas chromatography (GC) 98 % min.; ethylbenzene
content as determined by GC less than 2 %; evaporation residue at 140 °C less than 0,002 g/100 ml; boiling
point 138 °C.
Reagent-grade ortho-xylene (4.1) shall be used as the reference solvent whenever there is a dispute between
laboratories on test results, unless the laboratories agree otherwise.
5 Procedure
5.1 Preparation of the xylene
5.1.1 Although stabilization of the xylene is not required, antioxidants shall be added to prevent degradation
when testing unstabilized powders or beads.
Butylated hydroxytoluene (BHT), 4,4-thiobis(6-tert-butyl-m-cresol) and tetrakis[methylene(3,5-di-tert-butyl-
4-hydroxyhydrocinnamate)]methane at an approximate concentration of 0,02 g/l of xylene have been found to
be effective stabilizers. Agitate with a magnetic stirrer bar and heat for a minimum of one hour at 80 °C to
90 °C to ensure thorough mixing of the antioxidants and the xylene. This heating temperature has been
chosen as it is suitable for BHT, which is relatively volatile.
5.1.2 Degas the xylene every 24 h by purging with nitrogen gas for a minimum of 1 h.
5.2 Determination of level of impurities in the xylene (solvent blank)
5.2.1 The purpose of the solvent blank is to determine the evaporation residue, i.e. the amount of foreign
matter in the xylene.
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ISO 16152:2005(E)
A blank test should preferably be run on every ne
...