ISSN 1070-4272, Russian Journal of Applied Chemistry, 2014, Vol. 87, No. 8, pp. 1167−1170. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © E.V. Dolgova, R.R. Mukhametov, 2014, published in Zhurnal Prikladnoi Khimii, 2014, Vol. 87, No. 8, pp. 1188−1192.
AND POLYMERIC MATERIALS
Polycyanurate Binder for Spheroplastics
E. V. Dolgova and R. R. Mukhametov
All-Russia Research Institute of Aviation Materials, ul. Radio 17, Moscow, 105005 Russia
Received August 28, 2014
Abstract—The approach to the development of the composition and the requirements to the physicochemical
and technological properties of binders used as the polymeric base for syntactic foams are formulated. The main
advantages and drawbacks of the binders used for spheroplastic fabrication, such as epoxy, polyurethane, phenolic,
and oligoester compounds, are discussed. The rheological properties and heat resistance of the polycyanurate binder
developed at the All-Russia Research Institute of Aviation Materials are studied. The binder is characterized by
long working life in the temperature interval up to 150°C. The results obtained and the properties of multilayer
structures with the spheroplastic based on this binder show that the suggested polycyanurate binder is suitable
for fabrication of spheroplastics.
The development of structural and functional materials
with essentially improved set of properties is a topical
problem and key avenue in many branches of industry
[1–3]. The demand for such materials is particularly
acute in aerospace engineering. In addition, the modern
aircraft industry is characterized by the trend toward
partial replacement of metallic structures used in engines
and force elements by structures made of polymeric
composite materials (PCMs), preserving the required
level of operation properties.
Spheroplastics (syntactic foams) consisting of
a polymeric matrix (binder) and a ﬁ ller consisting of
hollow spherical particles (microballoons) distributed
in the binder are one of the kinds of ﬁ lled PCMs; they
have found use in the aircraft industry. For example,
spheroplastics are used in aerospace engineering for
ablation insulation and for production of various structural
parts of aircrafts [4–6]. Owing to sufficiently high
strength characteristics at relatively low density, syntactic
materials are used in various branches of engineering. For
example, they are used as insulation material for pipelines
, as composite carcass material in ship building, and as
a plaster or mastic for restoration of hydraulic structures
and submarine bodies . The capability of syntactic
foams to withstand hydrostatic compression makes them
unique materials for ensuring the ﬂ oatability under water.
Spheroplastics have also found wide use in building,
electrical engineering, and electronics .
The microballoons can be produced from glass,
polymers, metals, ceramics, and carbon. The most
widely used binders in production of spheroplastics are
composites based on epoxy resins. Syntactic foam based
on epoxy resin and amine curing agent is described in a
patent . The choice of a polymeric base of this type is
governed by the monolithic structure and low shrinkage
of the binder, and also by the possibility of readily
controlling the physicomechanical properties by choosing
appropriate combinations of the starting components.
The main drawback of epoxy binders in fabrication of
spheroplastics is high viscosity at room temperature,
which can be compensated by using diluents . Syntactic
foams based on polyurethane resins exhibit satisfactory
heat-insulation properties, but high water sorption
typical of polyurethanes requires using an additional
coating for making the material waterproof. Phenolic
and oligoester resin binders are also used as the base for
spheroplastics. Materials based on these resins undergo
strong shrinkage on curing, which leads to cracking.
However, they are cheaper than epoxy syntactic foams.
Phenolic spheroplastics are produced using cold-curable
binders based on novolac and resol oligomers. Low
apparent density is an advantage of polyester syntactic