SIST EN ISO 8975:1999

SLOVENSKI STANDARD
01-maj-1999
3ROLPHUQLPDWHULDOL±)HQROQHVPROH±'RORþHYDQMHS+,62
Plastics - Phenolic resins - Determination of pH (ISO 8975:1989)
Kunststoffe - Phenolharze - Messung des pH-Wertes (ISO 8975:1989)
Plastiques - Résines phénoliques - Détermination du pH (ISO 8975:1989)
Ta slovenski standard je istoveten z: EN ISO 8975:1995
ICS:
83.080.10 Duromeri Thermosetting materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL
STANDARD
First edition
1989-10-01
Plastics - Phenolic resins - Determination of pH
Plastiques - Rhines phhobques - DcStermination du pH
Reference number
IS0 8975: 1989(E)
IS0 8975:1989(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, govern-
mental 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 approval before their acceptance
as International Standards by the IS0 Council. They are approved in
accordance with IS0 procedures requiring at least 75 % approval by the
member bodies voting.
International Standard IS0 8975 was prepared by Technical Committee
ISO/TC 61, Plastics.
Annex A of this International Standard is for information only.
0 IS0 1989
All rights reserved. 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.
lnternationa I Orga nization for Standardiz ation
Switzerland
Case Postal e 56 l CH-121 1 Geneve 20 @
Printed in Switzerland
ii
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IS0 8975:1989(E)
INTERNATIQNAL STANDARD
Plastics - Phenolic resins - Determination of pH
3.2 Hydrogen phosphate buffer solution, containing
1 Scope
approximately 0,025 mol of potassium dihydrogen
phosphate (KH,PO,) per litre and approximately
This International Standard specifies a method for
0,025 mol of sodium hydrogen phosphate (Na,HPO,)
the determination of the pH of liquid phenolic resins
per litre, pH = 6,88 at 23 “C.
at the manufacturing stage or on the market.
Dissolve 3,39 g of potassium dihydrogen phosphate
NOTE 1 A variant of this method, applicable to solid
(KH,PO,) and 3,53 g of sodium hydrogen phosphate
phenolic resins, is described in annex A. With liquid resins
(Na,HPO,), previously dried by heating at 110 “C to
having a viscosity greater than 2 Pas, it may be neces-
130 “C for 2 h, in water and make up to 1000 ml.
sary to use this variant, which calls for a magnetic stirrer.
This solution may be kept longer by adding a crystal
of thymol.
2 Principle
3.3 Sodium tetraborate (Borax), standard solution,
c(Na,B,O,.lOH,O) = 0,Ol mol/l, pH = 9,22 at 23 “C.
The potential difference between a glass electrode
and a reference electrode immersed in the same
Dissolve 3,80 g of sodium tetraborate deca-
solution is used to determine the pH.
hydrate (Na,B,O,.lOH,O) in water and dilute to
1000 ml.
4 Apparatus
3 Reagents
4.1 pH-meter, accurate to 0,l pH-units.
During the analysis, use only reagents of recognized
analytical grade and only distilled water or water of
4.2 Electrodes
equivalent purity.
Standard solutions, with acid pH (E 4), neutral pH
4.2.1 Measuring electrode: glass electrode.
(Z 7) or alkaline pH (z 9), or buffer solutions.
4.2.2 Reference electrode: calomel electrode.
The following standard or buffer solutions are speci-
fied:
4.2.3 Maintenance of the electrodes
3.1 Potassium hydrogen phthalate, standard sol- For all types of electrode, follow the manufacturer ’s
ution, c(KCOOC,H,COOH) = 0,05 mol/l, pH = 4,00 instructions specifying the maintenance procedures
at 23 “C. necessary to keep the electrodes in the correct
condition.
Dissolve IO,21 g of potassium hydrogen phthalate,
previously dried by heating at 100 “C to 130 “C for In particular, clean the glass electrode at regular
2 h, in water and make up to 1000 ml. intervals as directed by the manufacturer.
This solution shall be stored in a glass vessel and
NOTE 2 When not in use over a long period, glass
kept away from any traces of acid or base; it may
electrodes and certain calomel electrodes may be stored
in the dry condition if permitted by the manufacturer.
be kept longer by adding a crystal of thymol. Slight
cloudiness in the solution indicates microbial con-
For reconditioning, soak the glass electrode in
tamination. The thymol is no longer effective and
acidified distilled water (pH 4 to 5) for several hours
such a solution shall be discarded.
IS0 8975:1989(E)
and the calomel electrode in saturated potassium the standard or buffer solution, taking into ac-
count its temperature, the apparatus is in oper-
chloride solution.
ating condition and is suitably calibrated.
Before each determination, wash the electrodes
with water and leave them to soak in water for at
- If this is not the case, determine the cause (such
least 2 min before making any measurements.
as operating error, defective electrode, incorrect
temperature correction) and remedy the defect.
5 Procedure
...