Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 10, pp. 1907−1910.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
L.Sh. Sadykova, R.R. Spiridonova, I.N. Bakirova, A.M. Kochnev, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 10,
AND POLYMERIC MATERIALS
Amidolysis of Polyurethane Wastes
L. Sh. Sadykova, R. R. Spiridonova, I. N. Bakirova, and A. M. Kochnev
Kazan State University of Technology, Kazan, Tatarstan, Russia
Received April 28, 2009
Abstract—Chemical degradation of various grades of polyurethane under the action of ε-caprolactam was
performed. The degradation rate depends on the polyurethane structure. Amidolysis of the urethane group was
proved by performing model reactions.
Steady growth of polyurethane (PU) production leads
to an increase in the volume of solid wastes formed.
Their elimination by incineration and disposal leads to
irrevocable loss of valuable resources and gives rise to
environmental problems. Therefore, the development
of procedures for utilization of PU wastes with their
recycling becomes an urgent problem.
Today, the best studied (and already implemented in
some countries) is chemical recycling by glycolysis. The
products formed in the process are used as components
in synthesis of PU of the same or another type, using
a standard technology .
At the same time, PU can be decomposed under the
action of other nucleophilic agents, in particular, amines
. However, commercial implementation of such
processes is impeded today by high cost and toxicity
of amine degradation agents. In this connection, we
examined in this study the chemical degradation of PU
under the action of a readily available, relatively cheap,
and low-toxic amine, ε-caprolactam (ε-CL).
Chemical degradation experiments were performed
with castable monolithic PUs of grades SKU-OM, SKU-
6, and SKU-PFL, which are widely used in production of
construction items. SKU-OM was prepared by the reaction
of poly(ethylene butylene glycol adipate) (PEBA) with
toluene 2,4-diisocyanate (TDI) in the presence of catalytic
amounts of phenolic Mannich bases at the molar ratio
TDI : PEBA = 1.15 : 1 . SKU-PFL and SKU-6 were
prepared, respectively, by the reaction of SKU-PFL-100
prepolymer with 4,4’-methylenebis(2-chloroaniline) at
the molar ratio SKU-PFL-100 : MOCA = 1 : 0.8 [3, 4]
and of TDI with polyethylene glycol adipate (PEA), 1,4-
butanediol (BD), and 1,1,1-trimethylolpropane (TMP)
at the molar ratio TDI : PEA : TMP : BD = 2 : 1 : 0.32 :
0.24. As degradation agent we used ε-CL produced by
the KuibyshevAzot Joint-Stock Company
Amidolysis was performed under argon in an oil-
heated 250-ml three-necked ﬂ ask equipped with a stirrer
and a thermometer at 160–200°С for 2.5 h. The ﬂ ask was
charged with ε-CL and preliminarily ground PU in weight
ratios of 80 : 20, 60 : 40, and 40 : 60.
To examine the mechanism of PU degradation, we
performed model reactions with compounds that can be
considered as structural models of the main chemical
bonds in PU, namely, with butyl phenylcarbamate
(PBC), N,N-diphenyl-N’-phenylurea (DPU), and dibutyl
phthalate (DBP). The reactions of these compounds with
ε-CL were performed in a two-necked ﬂ ask under argon
at 150°С for 2.5 h at equimolar ratio of the reactants.
The melting points of the degradation products were
determined by the capillary procedure .
The IR spectra of the products were recorded on
a Perkin–Elmer spectrophotometer (model РС-16) using
H NMR spectra were taken on a Bruker-
700 device operating at 700 MHz (for protons). The
measurement error was 2%. Carbon tetrachloride was
used as solvent.