EN ISO 7327:1997

SLOVENSKI STANDARD
01-maj-1999
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Plastics - Hardeners and accelerators for epoxide resins - Determination of free acid in
acid anhydride (ISO 7327:1994)
Kunststoffe - Härter und Beschleuniger für Epoxidharze - Bestimmung der freien Säure
in Säurenanhydrid (ISO 7327:1994)
Plastiques - Durcisseurs et accélérateurs pour résines époxydes - Détermination de
l'acide libre dans l'acide-anhydrique (ISO 7327:1994)
Ta slovenski standard je istoveten z: EN ISO 7327:1997
ICS:
83.080.10 Duromeri Thermosetting materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL
ISO
STANDARD 7327
First edition
1994-07-01
Plastics - Hardeners and accelerators for
epoxide resins - Determination of free
acid in acid anhydride
Plas tiques - Durcisseurs et acc6Mrateurs pour r&ines 6poxydes -
DAtermination de I ’acide libre dans I ’acide-anhydride
Reference number
ISO 7327: 1994(E)
ISO 7327:1994(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. Esch member body interested in a subject for
which a technical committee has been established has the right to be re-
presented 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 7327 was prepared by Technical Committee
lSO/TC 61, Plastics, Subcommittee SC 12, Thermosetting materials.
0 ISO 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronie or mechanical, including photocopying and
microfilm, without Permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-I 211 Geneve 20 l Switzerland
Printed in Switzerland
ii
INTERNATIONAL STANDARD 0 ISO ISO 7327:1994(E)
Plastics - Hardeners and accelerators for epoxide
resins - Determination of free acid in acid anhydride
1 Scope 4 Reagents
This International Standard specifies a method for the During the analysis, unless otherwise stated, use only
determination of free acid in acid anhydride hardeners reagents of recognized analytical grade and only dis-
tilled water or water of equivalent purity.
and accelerators for epoxide resins.
NOTE 1 This method is suitable for most anhydrides ex-
4.1 Butan-i-one (methyl ethyl ketone), dried us-
cept for Polyester and oligomeric anhydrides which may
give too wide a scatter of results. ing the following procedure:
Put 100 g of molecular sieve 4A into 1 litre of
butan-2-one. After allowing to settle for 24 h, decant
2 Normative reference
off the supernatant liquid, taking care that it does not
contain any molecular sieve 4A particles.
The following Standard contains provisions which,
through reference in this text, constitute provisions
Determine the water content of the dried butan-2-one
of this International Standard. At the time of publica-
by the Karl Fischer method (see ISO 760). Reject
tion, the edition indicated was valid. All Standards are
butan-2-one containing more than 20 ppm of water.
subject to revision, and Parties to agreements based
on this International Standard are encouraged to in-
4.2 Toluene, dried using the following procedure:
vestigate the possibility of applying the most recent
edition of the Standard indicated below. Members of
Put 100 g of molecular sieve 4A into 1 litre of toluene.
IEC and ISO maintain registers of currently valid
After allowing to settle for 24 h, decant off the
International Standards.
supernatant liquid, taking care that it does not contain
any molecular sieve 4A particles.
ISO 760: 1978, Determination of water - Karl Fischer
method (General method).
Determine the water content of the dried toluene us-
ing the Karl Fischer method (see ISO 760). Reject
toluene containing more than 20 ppm of water.
3 Principle
4.3 Rhodamine 6G solution.
The small amount of free acid present in a test portion
of acid anhydride hardener or accelerator is reacted
with rhodamine 6G to colour the test Solution pink.
4.3.1 Preparation
The absorbance of the coloured Solution is measured
at a wavelength of about 510 nm using a Disperse 20 mg of rhodamine 6G in IO ml of a buffer
spectrometer, and the free-acid content determined Solution [0,1 g of sodium Phosphate (Na,PO,) dis-
from a calibration curve. solved
...