This International Standard specifies a method for the
determination of the pH of polymer dispersions and
rubber latices (natural and synthetic) by means of a
pH-meter equipped with a combined glass and silver
reference electrode.
The method is also suitable for prevulcanized latex
and compounds containing polymer dispersions or
rubber latices, including adhesives.
NOTE 1 The accuracy of the method decreases at pH
values above 11.
Users should note that this edition of ISO 976 not only
represents a revision of the previous edition, but also
supersedes ISO 1148:1980, Plastics -- Aqueous
dispersions of polymers and copolymers -- Determi-
nation of pH. This edition represents a harmonized
version of the two standards.
One of the major changes in this new edition of
ISO 976 is the use of a combined electrode rather
than the separate electrodes used in the previous
edition, the combined electrode being considered
superior to the separate electrodes since the latter
are prone to latex deposits blocking the electro-
lyte iunction, thus adversely affecting repeatability.
Although older-type twin electrodes are capable of
giving accurate results, they should be progressively
replaced because of this problem of cleaning and
repeatability.