Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 11, pp. 1987−1992.
Pleiades Publishing, Ltd., 2010.
Original Russian Text © E.I. Andreikov, I.S. Amosova, O.V. Krasnikova, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 11, pp. 1855−1860.
AND INDUSTRIAL ORGANIC CHEMISTRY
Thermal Dehydrochlorination of Polyvinyl
Chloride in Coal-Tar Pitch
E. I. Andreikov, I. S. Amosova, and O. V. Krasnikova
Postovskii Institute of Organic Synthesis, Ural Branch, Russian Academy of Sciences, Yekaterinburg, Russia
Received January 20, 2010
Abstract—Effect of coal-tar pitch and anthracene fraction on the pyrolysis of polyvinyl chloride was studied.
Thermal destruction of polyvinyl chloride (PVC) is
being extensively studied both in a search for ways to im-
prove the working stability of this widely used polymer
 and in development of methods for its utilization .
Because PVC constitutes 5–10%  of the total amount
of plastics in municipal waste, a large number of studies
have been concerned with pyrolysis of PVC alone [4–10]
and its mixtures with other plastics [11–16].
Comparatively less studied is the effect of solvents
on the thermal destruction of PVC. A solvent can
differently affect the dehydrochlorination of PVC, the
ﬁ rst stage of the thermal destruction of this polymer. It
has been reported  that the thermal destruction of
PVC in nonpolar solvents, decalin and tetralin, under
elevated pressure occurs similarly to the destruction
of PVC alone to give an insoluble residue, oils, and
hydrogen chloride (HCl). The dehydrochlorination rate
increases with the basicity of an organic solvent [18, 19].
In the case of PVC pyrolysis in coal-tar pitch
under atmospheric pressure, a signiﬁ cant rise in the
rate and a decrease in the temperature of thermal
dehydrochlorination was observed, together with
a nonadditive change of the properties of the nonvolatile
residue, modiﬁ ed pitch, because of the chemical
interaction between the primary products formed in
thermal destruction of PVC with compounds contained
in coal-tar pitch . In this study, the properties of
pitches produced in joint pyrolysis of coal-tar pitch
and PVC at temperatures of 300 and 400°C under
conditions of nearly complete removal of HCl from
the mixture were analyzed. It was shown that pitches
with increased content of toluene-insoluble substances
and high softening point are formed at 300°C because
of the formation of cross-linked 3D structures involving
dehydrochlorinated PVC. However, it remained unclear
whether these reactions occur immediately after the
elimination of HCl or at higher temperatures of up to
Lowering the temperature of thermal dehydro-
chlorination of PVC is of particular interest because, in
this case, the temperature interval between the stages of
dehydrochlorination and thermal decomposition of the
organic mass in thermal methods for processing of spent
plastics can be made wider and the hazard of appearance
of organochlorine compounds in organic products of
pyrolysis can be diminished.
The goal of our study was to examine the reaction of
PVC dehydrochlorination in coal-tar pitch by DSC and
TG methods and to analyze properties of nonvolatile
products of joint pyrolysis, modiﬁ ed pitches, obtained
in the temperature range 180–225°C at various degrees
We used suspended PVC of S-70 brand with M =
5.5 × 10
and particle size smaller than 0.5 mm, industrial
samples of medium-temperature coal-tar pitch (CP) and