1070-4272/02/7511-1736$27.00C2002 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 75, No. 11, 2002, pp. 1736!1739. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 11,
2002, pp. 1772!1775.
Original Russian Text Copyright + 2002 by Obraztsova, Simenyuk, Eremenko.
AND INDUSTRIAL INORGANIC CHEMISTRY
Effect of Chemical Modification of Ultradispersed Copper
Powders on Electrical Conductivity of Formulations
on Their Base
I. I. Obraztsova, G. Yu. Simenyuk, and N. K. Eremenko
Institute of Coal and Coal Chemistry, Siberian Division, Russian Academy of Sciences, Kemerovo, Russia
Received March 13, 2002
Abstract-Ultradispersed powders of copper were obtained by reducing various copper salts with glycerol,
and formulations on their base were prepared. The effect of various modifiers on the dispersity, stability, and
electrical conductivity of copper powders was examined.
Synthesis and study of ultradispersed powders
(UDPs) of metals and development of electrically
conducting materials on their base is a topical direc-
tion of research in modern science. Recently, increas-
ing attention has been given to copper [1, 2], which is
virtually as good as noble metals as regards its elec-
trical conductivity  and much less expensive.
However, copper powders exhibit rather high activity
and are oxidized in the course of time, which inevita-
bly impairs the conductivity. This problem can be
solved by optimizing the preparation process, modify-
ing the surface of copper UDPs, and creating formula-
tions on their base, whose electrically conducting
properties are preserved for a long time. Data on the
longevity of electrically conducting formulations are
virtually lacking from the literature.
Previously, two methods for obtaining copper
UDPs have been developed [6, 7]. These methods are
based on reduction of copper sulfate with glycerol.
The optimal temperature, time, and reagent concentra-
tions were determined. Also, the influence exerted
by organic acids with reducing properties (ascorbic,
citric, etc.) on the reaction of copper sulfate with
glycerol and on the properties of the copper powders
obtained was examined. It was established that addi-
tions of these acids accelerate the reaction by a factor
of 536, allow the process temperature to be decreased
by 20340oC, and ensure enhanced stability and elec-
trical conductivity of the resulting copper UDPs.
It was also found that, upon an appropriate treat-
ment with solutions of hydroquinone and stearic acid
in ethanol or pentane, copper UDPs possess increased
dispersity (average particle size 20330 nm), stability,
and electrical conductivity. Furthermore, powders
treated with pentane can be stored for a long time not
only in solution, but also in air.
In this work, we prepared UDPs from various
copper(II) salts and examined the influence exerted by
chemical modification of copper UDPs on the elec-
trical conductivity and stability of formulations on
their base. The data obtained in the study are com-
pared with those published previously [8, 9]. New
data on the formulation longevity are presented.
Copper UDPs were prepared by reducing various
copper salts with glycerol by the method described in
. However, it was found that complete reduction of
readily decomposing salts (acetate, basic carbonate,
and tartrate) requires smaller amount of glycerol,
lower temperature T
, and shorter reaction time t
results obtained at different copper salt to glycerol
mass ratios A are presented in Table 1. It can be seen
that the reduction of copper basic carbonate, acetate,
and tartrate is the most effective, and their formula-
tions with novolac show high electrical conductivity
and are stable for a long time (more than 5 years)
without addition of any stabilizers. Here, copper UDP
is presumably stabilized in the course of the reaction
by glycerol itself.
It also follows from Table 1 that, in reduction of
copper(II) sulfate, the electrical conductivity of the
resulting formulations falls dramatically when no ad-
ditional stabilizers are introduced into the resin (ex-
periment no. 1). When, however, modifiers are intro-
duced (experiment no. 2), the formulations obtained