AND POLYMERIC MATERIALS
Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 3, pp. 432−436.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © A.R. Kurbangaleeva, A.I. Kurkin, Yu.N. Khakimullin, 2012, published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 3, pp. 460−464.
Structure and Properties of Thiokol Sealants
Modiﬁ ed with Organosilanes
A. R. Kurbangaleeva, A. I. Kurkin, and Yu. N. Khakimullin
Kazan National Research University of Technology, Kazan, Tatarstan, Russia
Received September 15, 2011
Abstract—The effect of functionalized organosilanes on the properties of sealants based on liquid Thiokol NVB-
2 was examined. The role of these agents in formation of the vulcanization network and of chemical bonds with
the substrates was analyzed.
It is known that sealants based on polysulﬁ de
oligomers (PSOs) without adhesion reactive additives
do not have satisfactory adhesion [1, 2]. The adhesion
properties of such sealants are improved by adding
epoxy–4,4'-isopropylidenediphenol and alkylphenol–
formaldehyde resins, acrylates, and functionalized
silanes, which are capable of chemical interaction both
with Thiokol itself and with various substrates [2–4].
Today the main ﬁ eld of using Thiokol sealants, thanks
to their high impermeability to gases, is sealing of glass
units. Such sealants should have high adhesion to glass
and duralumin. High adhesion to these structures is
ensured by organosilanes that can efﬁ ciently interact
with terminal SH groups of liquid Thiokol and with
hydroxy groups and glass and duralumin. Introduc-
tion of such silanes in small amounts (0.2 to 1.5 wt %
relative to Thiokol) allows substantial improvement of
not only adhesion, but also the whole set of properties
of the sealants.
In this study we examined the curing, structure,
and properties of sealants based on liquid Thiokol and
modiﬁ ed with organosilanes.
We took NVB-2 liquid Thiokol containing
3.52 wt % SH groups. As a filler we used M5G
hydrophobic chalk taken in an amount of 100 wt
parts per 100 wt parts of liquid Thiokol. The liquid
Thiokol was cured with manganese dioxide taken in the
form of curing paste no. 9. As vulcanization accelerator
we used diphenylguanidine (DPG). The weight ratio
of the sealing and curing pastes was 100 : 10. The
curing was performed in the accelerated mode (70°C,
24 h). Tests were performed by standard procedures
involving determination of the nominal strength,
relative elongation at break, and relative elongation set
in accordance with GOST (State Standard) 21751–76;
the adhesion of the sealant to duralumin and glass was
determined in accordance with GOST 209–75, and the
cross-linking density, by the Cluff–Gladding method .
As adhesion additives we used bis(3-triethoxysilylpropyl)
tetrasulfide (Silan-69), vinyltriethoxysilane
(MPTMS), γ-aminopropyltriethoxysilane (AGM), and
We found that introduction of organosilanes accelerates
the curing. The strongest effect is exerted by AGM owing
to the presence of a primary amino group which, together
with DPG, accelerates the oxidation with manganese
dioxide. The observed acceleration of curing with the
other organosilanes, which do not contain amino group,
can be attributed to their participation in formation of the
network in the course of curing, which occurs in two steps.
In the ﬁ rst step, organosilanes in the course of storage in