EN ISO 8988:1997

SLOVENSKI STANDARD
SIST EN ISO 8988:1999
01-maj-1999
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Plastics - Phenolic resins - Determination of hexamethylenetetramine content - Kjeldahl
method and perchloric acid method (ISO 8988:1995)
Kunststoffe - Phenolharze - Bestimmung des Hexamethylentetramingehaltes - Kjeldahl-
Methode und Perchlorsäuremethode (ISO 8988:1995)
Plastiques - Résines phénoliques - Détermination de la teneur en
hexaméthylenetétramine - Méthode Kjeldahl et méthode a l'acide perchlorique (ISO
8988:1995)
Ta slovenski standard je istoveten z: EN ISO 8988:1997
ICS:
83.080.10 Duromeri Thermosetting materials
SIST EN ISO 8988:1999 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 8988:1999

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SIST EN ISO 8988:1999

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SIST EN ISO 8988:1999

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SIST EN ISO 8988:1999
IS0
INTERNATIONAL
STANDARD 8988
Second edition
1995-05-01
- Phenolic resins -
Plastics
Determination of hexamethylenetetramine
content - Kjeldahl method and perchloric
acid method
P/as tiques - Rgsines ph&oliques - D&ermination de la teneur en
hexam&hyl6net&ramine - Mkthode Kjeldahl et m&hode a I’acide
perchlorique
Reference number
IS0 8988:1995(E)

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SIST EN ISO 8988:1999
IS0 8988:1995(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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. IS0
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 IS0 8988 was prepared by Technicai Committee
lSO/TC 61, Plastics, Subcommittee SC 12, Thermosetting materials.
edition cancels and the first
This second replaces edition
(IS0 8988:1989), of which it constitutes a minor revision.
0 IS0 1995
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 Standardiza tion
Case Postale 56 l CH-121 1 Geneve 20 l Switzerland
Printed in Switzerland
ii

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SIST EN ISO 8988:1999
INTERNATIONAL STANDARD 0 IS0 IS0 8988: 1995(E)
- Phenolic resins - Determination of
Plastics
hexamethylenetetramine content - Kjeldahl method
and perchloric acid method
The method is applicable to hexamethylenetetramine
1 Scope
contents of 3 0,5 % (m/m).
This International Standard specifies two methods for
the determination of the hexamethylenetetramine
3.2 Principle
(“hexa”) content of phenolic resins. The two methods
are equivalent. The Kjeldahl method described in
The hexamethylenetetramine in a test portion is con-
clause 3 is not applicable if there are other compo-
verted to ammonium bisulfate by decomposition in
nents containing nitrogen in the phenolic resin. The
hot concentrated sulfuric acid and in the presence of
perchloric acid method described in clause 4 is only
a catalytic mixture.
applicable if there are no other basic or acidic addi-
tives in the resin.
The ammonium bisulfate is converted to sodium sul-
fate and ammonia by reaction with sodium hydroxide.
2 Normative reference
The ammonia is distilled off and collected in hydro-
chloric acid.
The following standard contains provisions which,
through reference in this text, constitute provisions
The excess hydrochloric acid is titrated with a stan-
of this International Standard. At the time of publi-
dard volumetric solution of sodium hydroxide in the
cation, the edition indicated was valid. All standards
presence of an indicator.
are subject to revision, and parties to agreements
based on this International Standard are encouraged
to investigate the possibility of applying the most re-
3.3 Reagents
cent edition of the standard indicated below. Mem-
bers of IEC and IS0 maintain registers of currently
During the analysis, unless otherwise stated, use only
valid International Standards.
reagents of recognized analytical grade, free of nitro-
gen, and only distilled water or water of equivalent
IS0 385-l :I 984, Laboratory glassware - Burettes -
purity.
Part 7 : General requirements.
3.3.1 Sulfuric acid, concentrated.
3 Kjeldahl method
WARNING - For safety reasons, the Kjeldahl de-
3.32 Kjeldahl catalytic mixture, consisting of
termination must be carried out in a well venti-
97 g of sodium sulfate decahydrate (Na,SO,=lOH,O),
lated hood.
I,5 g of copper sulfate pentahydrate (CUSO,~~H,O)
and I,5 g of selenium (Se).
3.1 General
3.3.3 Sodium hydroxide, 30 % (m/m) solution.
This clause specifies a method for the determination
of total nitrogen, expressed as hexamethylene-
tetramine, in phenolic resins. 3.3.4 Hydrochloric acid, c(HCI) = 0,lO mol/l.
1

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SIST EN ISO 8988:1999
0 IS0
IS0 8988:1995(E)
the receiver and titrate the excess hydrochloric acid
3.3.5 Sodium hydroxide, standard volumetric sol-
ution, c(NaOH) = 0,lO mol/l. with sodium hydroxide solution (3.3.5) using the
burette (3.4.3).
3.3.6 Mixed indicator, solution.
3.6 Expression of results
Dissolve 60 mg of methyl red and 40 mg of
methylene blue in 100 ml of ethanol.
The hexamethylenetetramine content, expressed as
a percentage by mass, is given by the formula
3.4 Apparatus
0,35(&J - v,)
mO
Ordinary laboratory apparatus, plus the following:
Kjeldahl flask, capacity
...