Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 7, pp. 1301−1304.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
N.P. Krut’ko, O.N. Opanasenko, O.V. Luksha, Yu.V. Loboda, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 7,
AND POLYMERIC MATERIALS
Thermal Oxidation Resistance of Bitumen Modiﬁ ed
and Ethylene–Vinyl Acetate Copolymers
N. P. Krut’ko, O. N. Opanasenko, O. V. Luksha, and Yu. V. Loboda
Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus, Minsk, Belarus
Received March 10, 2008
Abstract—The effect of a blend of styrene–butadiene–styrene and ethylene–vinyl acetate copolymers on the
heat resistance of oxidized bitumen was examined. The structural and rheological properties of the modified
bitumen were analyzed.
An efficient way to control physicomechanical,
structural, and rheological properties of oxidized bitumens
is to alter their colloidal structure by modiﬁ cation with
macromolecular reagents [1–3]. The effects of polymeric
additives are different. However, as a rule, if the polymer
is compatible with the bitumen, the compound acquires
a set of valuable properties of the polymer: elasticity,
lower fluidity at elevated temperatures, and crack
resistance and ﬂ exibility at lowered temperatures. The
strength and longevity of asphalt concrete pavements
prepared on the basis of polymer–bitumen compounds
(PBCs) is largely determined by the resistance of the
modified bitumen to thermal oxidative degradation.
Elevated temperatures start to strongly affect the PBC
structure already in the step of preparing asphalt concrete
mix, in the course of mixing heated mineral material
with bitumen. The structurization of asphalt concrete is
complete in the course of its densiﬁ cation. Each step of
the process is accompanied by quantitative changes in
structural and rheological properties of bitumen [4, 5]. In
the course of operation of an asphalt concrete pavement,
the structure and properties of bitumen are subject to
the impact of temperature and atmospheric oxygen.
Chemical transformations in PBC in the course of thermal
oxidation mainly involve two processes: cross-linking and
degradation of macromolecules of the dispersed phase.
The ﬁ rst process results in formation of three-dimensional
polymeric structures, which leads to enhancement of
the PBC strength. However, this is accompanied by the
loss of elasticity. The compound becomes brittle, and
the required service characteristics are lost. The second
process, degradation, leads to cleavage of molecular
chains and decrease in the molecular weight of the poly-
mer. As a result, PBC loses the mechanical strength .
Previous studies  showed that styrene–butadiene–
styrene (SBS) thermoelastoplastic enhances the strength
and viscoelastic characteristics of bitumen and makes
it less sensitive to temperature. However, a signiﬁ cant
drawback of SBS-modiﬁ ed bitumen is its poor resistance
to thermal oxidative degradation. One of possible ways
to overcome this drawback, with preservation of all
the positive properties of SBS-modiﬁ ed bitumen, is
joint introduction into bitumen of styrene–butadiene–
styrene and ethylene–vinyl acetate (EVA) copolymers.
It is assumed that the polar carbonyl group in EVA
macromolecules can interact with bitumen asphaltenes,
preventing their coalescence and displacement of the
dispersion medium (malthene fraction) associated with
them, and thus preventing PBC from becoming more
viscous and brittle.
In this study we evaluated the heat resistance of
bitumen modiﬁ ed with SBS and ethylene–vinyl acetate