1070-4272/02/7508-1339 $27.00 C 2002 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 75, No. 8, 2002, pp. 1339!1344. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 8, 2002,
Original Russian Text Copyright C 2002 by E. Nefed’ev, Rakhmatullin, Orlinskii, Petrov, S. Nefed’ev, Yagudin.
AND POLYMERIC MATERIALS
The Nature of Copper(II) Complexes in the Transition Layer
of Thiokol Sealant!Brass Adhesive Joint
E. S. Nefed’ev, R. M. Rakhmatullin, S. B. Orlinskii, O. V. Petrov,
S. E. Nefed’ev, and Sh. G. Yagudin
Kazan State Technological University, Kazan, Tatarstan, Russia
Kazan State University, Kazan, Tatarstan, Russia
Received November 5, 2001; in final form, April 2002
Abstract-Copper(II) complexes formed in the interphase area between Thiokol3epoxy adhesive and brass
support were studied using the method of the envelope of modulation of the electron spin echo.
Brass plating is a well-known and widely used
method of strengthening adhesive joints between
a metal and a rubber. High strength of rubber3brass
adhesive joints is due to the interaction of macromol-
ecules with a sulfide (Cu
S) film formed at
the brass surface owing to chemisorption of sulfur
added either as a vulcanizer or as an adhesive ad-
ditive. The nature of this interaction is not yet fully
understood. Some researches assume that the high
adhesive strength is mainly caused by chemical bonds
formed between rubber and surface sulfides, whereas
others assume adsorption bonding, facilitated by the
high specific surface of the sulfide film [1, 2]. In any
case, the necessary component of the rubber stock
is sulfur, since without sulfur the adhesion of rubber
to the brass surface is poor.
Here we consider one of the factors governing
the adhesion strength of such systems, namely, com-
plex formation at the interface of brass and sealant
based on polysulfide oligomer (liquid Thiokol). Pre-
vious studies have shown that, in contact of Thiokol
sealant with the brass surface, paramagnetic copper(II)
complexes are formed, and their concentration varies
in parallel with the content of free sulfur added as
an adhesive additive to the mixture [3, 4]. It has been
suggested  that the ligands are organic and are co-
ordinated via sulfur atom.
A more detailed study of the forming copper com-
plexes is required in view of the established relation-
ship between their concentration and the adhesion
(Fig. 1). Additional data on the structure of ligands
would give a possibility of directed control over adhe-
sion characteristics of a sealant by varying its formula.
In addition, these data are useful for development of
theoretical concepts of the adhesion mechanism.
The sealant composition was based on liquid
Thiokol of the LP-977 brand (100 wt parts)
where k + n + m =12314 and R is
3, and epoxy resin of E-40 brand
(20 wt parts).
Fig. 1. Adhesion A and relative intensity I/I
of the ESR
signal vs. sulfur content c.