ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 5, pp. 838!841. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + A.A. Gorbatovskii, D.A. Rozental’, S.V. Dronov, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 5,
AND POLYMERIC MATERIALS
Structure and Composition of Polymer!Bitumen Composites
A. A. Gorbatovskii, D. A. Rozental’, and S. V. Dronov
St. Petersburg State Technological Institute, St. Petersburg, Russia
Received January 25, 2007
Abstract-Features of the composition and structure of polymer3bitumen composites are examined, including
the effects of the amount and quality of the basic components on the characteristics of the final product.
The effect of butadiene3styrene thermoplastic elastomer on the properties of the cold applied polymer3
bitumen mastic is considered. Typical component mixing schemes are analyzed, and a flowsheet for produc-
tion of polymer3bitumen mastic is presented.
Polymer3bitumen composites are widely used in
production of mastics for various purposes and ad-
vanced paving mixes, and in repair of critical sections
of highways and airfield paving. Presently, there are
a lot of patents on the composition of such materials.
However, no general theory substantiating the proc-
esses for their production is developed yet, since there
is no common view of the behavior of bitumen and
polymers in preparation of composites.
It is a common view that heavy oil residues includ-
ing bitumens are colloid systems: the dispersion medi-
um is represented by oils and resins (so-called mal-
thenes), and the dispersed phase, by solid lamellar-
block asphaltene particles. According to the modern
views, molecules of practically all components of
petroleum bitumens are built on the same principle.
Molecules of both hydrocarbons and their hetero
derivatives are hybrid compounds with a polycyclic
core containing 43 6 rings, mostly six-membered.
This polycyclic system may have several methyl and
one long-chain (C
) alkyl substituents. The cyclic
part of the molecule may include sulfur- or nitrogen-
containing rings, the oxygen-containing functional
groups being arranged mostly at the periphery of
the molecule [1, 2].
The feature of the structure of asphaltene molecules
is that they have three aromatic or heteroaromatic
rings. This ensures the practically planar structure of
asphaltene molecules; as a result of interaction of
p-electron clouds with polar groups, they build asso-
ciates in the form of stacks of parallel planar mole-
cules. Therefore, asphaltenes of bitumen occur as
extremely fine solid particles (1.232.5 nm) surrounded
by solvate shells, which are spread among oil and
resin molecules [2, 3].
The structure of a colloid system controls its char-
acteristics. Therefore, the properties of bitumens are
controlled by the concentration of asphaltenes (dis-
persed phase), component composition of malthenes
(dispersion medium), and degree of their aromaticity.
This is clearly demonstrated by the dependence of
the softening point on the composition of bitumen:
the softening point increases with increasing asphalt-
Depending on the asphaltene content, bitumens
form sols, sol3gel structures, and gel-like structures
(at the maximal asphaltene content). Different energy
is required to destroy these structures. This energy is
indirectly characterized by the softening point, which
is higher for bitumens having a gel structure. In all
the indicated structures, asphaltene particles are sur-
rounded by solvate shells, preventing their adhesion.
The higher the asphaltene concentration, the smaller is
the dispersion medium space between the particles. At
a certain asphaltene content, their solvate shells are
brought in contact with each other to form clusters,
which, in turn, are surrounded by a solvate shell of
the molecules of the dispersion medium. Further in-
crease in the asphaltene content results in adhesion of
the clusters with formation of a rigid framework in
bitumen (bitumens of structural and some special
grades). However, in this case, when practically the
entire dispersion medium is converted into a solvation
shell, asphaltenes do not form an individual phase.
Therefore, it is asphaltenes that most significantly
affect the strength and softening point of bitumen .