Reinforced plastics based on unsaturated-polyester resins -- Determination of the residual styrene monomer content, as well as the content of other volatile aromatic hydrocarbons, by gas chromatography

ISO 4901:2011 specifies a method for the determination, by gas chromatography, of the residual styrene monomer in reinforced plastics based on unsaturated polyester (UP) resins in the polymerized state. The residual styrene monomer content is an important criterion in evaluating the degree of cure of UP resins in the polymerized state. The method can also be used for the simultaneous determination of other volatile aromatic hydrocarbons in UP resins. The method is not applicable to UP resins of high chemical resistance.

Plastiques renforcés à base de résines de polyesters non saturés -- Détermination du styrène monomère résiduel, ainsi que d'autres hydrocarbures aromatiques volatils, par chromatographie en phase gazeuse

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Status
Published
Publication Date
08-Aug-2011
Current Stage
6060 - International Standard published
Start Date
29-Jul-2011
Completion Date
09-Aug-2011
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ISO 4901:2011 - Reinforced plastics based on unsaturated-polyester resins -- Determination of the residual styrene monomer content, as well as the content of other volatile aromatic hydrocarbons, by gas chromatography
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INTERNATIONAL ISO
STANDARD 4901
Second edition
2011-08-15
Reinforced plastics based on
unsaturated-polyester resins —
Determination of the residual styrene
monomer content, as well as the content
of other volatile aromatic hydrocarbons,
by gas chromatography
Plastiques renforcés à base de résines de polyesters non saturés —
Détermination du styrène monomère résiduel, ainsi que d'autres
hydrocarbures aromatiques volatils, par chromatographie en phase
gazeuse
Reference number
ISO 4901:2011(E)
ISO 2011
---------------------- Page: 1 ----------------------
ISO 4901:2011(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2011

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 either ISO at the address below or

ISO's member body in the country of the requester.
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Published in Switzerland
ii © ISO 2011 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 4901:2011(E)
Contents Page

Foreword ............................................................................................................................................................ iv

Introduction ......................................................................................................................................................... v

1  Scope ...................................................................................................................................................... 1

2  Normative references ............................................................................................................................ 1

3  Terms and definitions ........................................................................................................................... 1

4  Principle ................................................................................................................................................. 1

5  Materials ................................................................................................................................................. 2

6  Apparatus ............................................................................................................................................... 2

7  Preparation of sample ........................................................................................................................... 3

8  Procedure ............................................................................................................................................... 3

8.1  General ................................................................................................................................................... 3

8.2  Preparation of extraction solvent ........................................................................................................ 3

8.3  Preparation of test solution .................................................................................................................. 3

8.4  Determination of glass and mineral content ...................................................................................... 3

8.5  Preparation of calibration solutions .................................................................................................... 4

8.6  Gas-chromatographic procedure ........................................................................................................ 4

9  Expression of results ............................................................................................................................ 6

9.1  Calculation of results from a calibration graph ................................................................................. 6

9.2  Calculation of the content of styrene (or another aromatic hydrocarbon) in the original UP

resin sample ........................................................................................................................................... 7

9.3  Calculation of the content of styrene (or another aromatic hydrocarbon) in the pure UP

resin ........................................................................................................................................................ 8

10  Test report .............................................................................................................................................. 8

Annex A (informative) Typical operating conditions ....................................................................................... 9

© ISO 2011 – All rights reserved iii
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ISO 4901:2011(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 4901 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 12, Thermosetting

materials.

This second edition cancels and replaces the first edition (ISO 4901:1985), which has been technically revised

(for details, see the Introduction).
iv © ISO 2011 – All rights reserved
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ISO 4901:2011(E)
Introduction

During the 25 years since publication of the first edition of this International Standard, ISO 4901:1985,

significant advances have been made in analytical techniques such as gas chromatography. The standard

has therefore been completely revised. The following are the main changes which have been made:

a) In addition to a gas-chromatographic method, the first edition of ISO 4901 included, as an alternative, a

classical method, Wijs' method, based on an iodometric titration. This method had been included in the

first edition for laboratories in which gas chromatography was not available. As, nowadays,

chromatography is considered to be a routine analytical tool, Wijs' method has been removed from the

standard.

b) Packed gas-chromatography columns have generally been replaced by open, tubular columns which

operate under completely different conditions. In the revised test method, therefore, only an open, tubular

column is used.

c) In addition, the gas-chromatographic method has been extended to cover not only styrene but also other

aromatic hydrocarbons which might have been used as solvents or starting materials in producing the

unsaturated polyester resin.
© ISO 2011 – All rights reserved v
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INTERNATIONAL STANDARD ISO 4901:2011(E)
Reinforced plastics based on unsaturated-polyester resins —
Determination of the residual styrene monomer content, as well
as the content of other volatile aromatic hydrocarbons, by gas
chromatography

WARNING — Persons using this document should be familiar with normal laboratory practice, if

applicable. This document does not purport to address all of the safety concerns, if any, associated

with its use. It is the responsibility of the user to establish appropriate safety and health practices and

to ensure compliance with any regulatory requirements.
1 Scope

This International Standard specifies a method for the determination, by gas chromatography, of the residual

styrene monomer in reinforced plastics based on unsaturated polyester (UP) resins in the polymerized state.

The residual styrene monomer content is an important criterion in evaluating the degree of cure of UP resins

in the polymerized state. The method can also be used for the simultaneous determination of other volatile

aromatic hydrocarbons in UP resins.
The method is not applicable to UP resins of high chemical resistance.
2 Normative references

The following referenced documents are indispensable for the application 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 472, Plastics — Vocabulary

ISO 1172, Textile-glass-reinforced plastics — Prepregs, moulding compounds and laminates — Determination

of the textile-glass and mineral-filler content — Calcination methods
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 472 apply.

4 Principle

Styrene is extracted from the UP resin in the polymerized state using dichloromethane. The styrene in the

extract is determined by gas chromatography, using an internal standard and a calibration curve.

© ISO 2011 – All rights reserved 1
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ISO 4901:2011(E)
5 Materials
5.1 n-Butylbenzene, analytical grade, for use as an internal standard.
5.2 Dichloromethane, analytical grade, for use as the extraction solvent.

WARNING — Dichloromethane is harmful when swallowed, inhaled or absorbed through the skin. It

affects the central nervous system, the liver, the cardiovascular system and the blood. It causes

irritation of the skin, eyes and respiratory tract. It is also a suspected cancer hazard, the risk of cancer

depending on the level and duration of exposure.

NOTE In view of the toxicity and suspected carcinogenic characterics of dichloromethane, acetone and ethyl acetate

are being tested as replacements. If the results of this work demonstrate conclusively that either one or both of these

solvents are suitable, this International Standard will be revised accordingly.

5.3 Styrene, analytical grade, and, if relevant, other aromatic hydrocarbons, such as toluene,

ethylbenzene and α-methylstyrene, also analytical grade.

NOTE An aromatic hydrocarbon is considered to be relevant if it is used as a solvent or starting material in the UP

resin production process.
5.4 Carrier gas and FID fuel gases:
 carrier gas: helium or nitrogen;
 FID fuel gases: hydrogen and air.
6 Apparatus
Normal laboratory equipment and the following apparatus are required:

6.1 Cutting device, equipped with a water-cooled diamond blade, for cutting the UP resin into strips of

width 1 mm to 2 mm.
6.2 Gas chromatograph, including the following components:
6.2.1 Injection port, equipped with a splitter, for use with liquid samples.
6.2.2 Open, tubular column, e.g. meeting the specifications given in Annex A.
6.2.3 Flame ionization detector (FID).

A typical instrument setup and typical operating conditions are given in Annex A. Other setups and operating

conditions may be used provided that the chromatograms obtained comply with the requirements given in

8.6.1.

6.3 Data processor, e.g. a computer (or the equivalent), to record the signals from the detector.

6.4 Sample injection syringe, i.e. a 1 µl microsyringe, either as a separate item of apparatus or

incorporated in the auto-injector of the gas chromatograph.
6.5 Analytical balance, accurate to 0,1 mg.
2 © ISO 2011 – All rights reserved
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ISO 4901:2011(E)
7 Preparation of sample

Polymerized UP resin pieces of any shape that will permit the production of strips of width 1 mm to 2 mm may

be used. Cut the polymerized pieces into strips of width 1 mm to 2 mm. Dry the strips and break them into

pieces of length approximately 10 mm. During cutting and drying, avoid any operation that could affect the

styrene and/or volatile-hydrocarbon content.
8 Procedure
8.1 General
Three test portions of the sample (see Clause 7) shall be analysed.

During the preparation, dilution and extraction processes described below, the temperature of all solutions

shall remain 25 °C.
8.2 Preparation of extraction solvent

Weigh, to the nearest 0,1 mg, (250  50) mg of n-butylbenzene (5.1) into a 1 000 ml volumetric flask

containing approximately 500 ml of dichloromethane (5.2). Make up to the mark with dichloromethane (see,

however, next paragraph) and mix.

Alternatively, acetone (see Note to 5.2) may be used instead of dichloromethane, provided that the results can

be demonstrated to
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