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TOLEDO (SPAIN)PYROLYSIS OF HALOGEN CONTAINING POLYMER MIXTURES
Zs. Czégény1, E. Jakab1, T. Bhaskar2,3 and Y. Sakata2
1Institute of Materials and Environmental Chemistry, Chemical Research Center, Hungarian Academy of Sciences, H-1525

Budapest P.O. Box 17, Hungary
2Department of Applied Chemistry, Okayama University, 3-1-1 Tsushima-Naka, Okayama 700-8530, Japan
3present address: Indian Inst Petr, Council Sci & Ind Res, Dehra Dun 248005, Uttar Pradesh Indiae-mail:czegeny@chemres.huAbstract
Thermal decomposition of various mixtures of acrylonitrile-butadiene-styrene copolymer containing brominated epoxy resin
flame retardant (ABS-Br), polyethylene terephthalate (PET) and polyvinylchloride (PVC) has been studied in order to clarify
the reactions between the components of mixed polymers. It was established that the decomposition rate curves (DTG) of
the mixtures were different from the summed curves of the individual components indicating the interactions between thedecomposition reactions of the polymer components. Both ABS and PET maximal rate of thermal decomposition decreases
significantly in the presence of each other. The dehydrochlorination rate of PVC was sensitive for the presence of ABS orPET. More than 40 halogen containing molecules have been identified among the pyrolysis products of mixed samples.
Brominated and chlorinated aromatic esters were detected from the mixtures containing PET and halogen-containing
polymers. A series of chlorinated, brominated and both chlorinated and brominated phenols and bisphenol A molecules havebeen identified among the pyrolysis products of polymer mixtures containing flame retarded ABS and PVC.

Keywords: ABS, PET, PVC, halogenated products, pyrolysis

1. Introduction
Pyrolysis is a promising alternative for the recycling ofplastic waste, because the process produces valuable
chemicals or fuels. However, pyrolytic recycling of waste
plastics require special attention due to their possible
halogen content, since it should be accompanied with theelimination of halogenated products.
Polymer wastes generally contain various polymers
together, in this way any component could affect thethermal decomposition reactions of the others.
PVC generally affects the decomposition of otherpolymers due to the catalytic effect of HCl released.
Chlorinated organic compounds have been identified in
the pyrolysis oil of the mixture of (PVC) and (PET)1.
Brominated epoxy resin is a widely used flame retardant
plastic, tetrabromobisphenol A is built in its polymer
structure. The thermal decomposition of this polymer
results in various bromobisphenols and bromophenols, inthis way the involvement of brominated epoxy is also a
potential source of environmental pollution2. Thermal
degradation of PET, PVC and ABS-Br containing
polymer mixtures was examined in a fixed bed reactor
and significant effect was found in the yield ofdegradation products3.
The detailed knowledge of halogenated products andtheir possible formation mechanism could help to find theproper way to eliminate these harmful materials from thepyrolysis oil, or to hinder their formation during pyrolysis
procedures.

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The aim of the present work is to investigate the thermal
decomposition process of polymer mixtures that can bepresent in plastics waste. Thermogravimetry-mass
spectrometry (TG/MS) technique was used to examine
the changes in the overall thermal decomposition ofpolymers in their mixtures. The qualitative analysis ofpyrolysis oil has been focused on the evolution of
halogenated organic compounds, and has been studied
by pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS).

2. Materials and Methods
PET was obtained from Eastman Kodak Co., Ltd andPVC from Geon Chemical Co. Ltd. Japan. Commerciallyavailable ABS copolymer containing brominated epoxy
oligomer flame retardant and Sb2O3 synergist (ABS-Br)(9.3 wt% Br and 3.8 wt% Sb ) was used in the present
investigation. The samples were mechanically mixed tosimulate the situation in the municipal waste. Binary andternary mixtures of the above polymer samples were
examined using compositions of 1:1 or 1:1:1 by weight.
TG/MS measurements were performed on a modified
Perkin-Elmer TGS-2 thermobalance and a HIDEN HAL
2/301 PIC quadrupole mass spectrometer. Typically 0.51 mg polymer samples were placed into the platinum
sample pan and heated at a 10°C min-1 up to 600°C inargon atmosphere.
Py-GC/MS measurements were carried out in a CDS
Pyroprobe 2000 equipped with a platinum coil and quartz
sample tube. The pyrolyzer was coupled to an Agilent
6890/5973 GC/MS instrument. About 0.4 mg polymer

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6th International Symposium on Feedstock Recycling of Polymeric Materials

sample was pyrolyzed at 600°C for 20 s in a quartz tube
using helium as a carrier gas.

3. Results and Discussion
3.1 TG/MS study
Thermogravimetry/mass spectrometry is a suitable
method for the examination of thermal decomposition
and analysis of the decomposition products under slow
heating rate. Binary and ternary mixtures of ABS-Br, PET
and PVC were examined. The thermal decompositions ofpure ABS-Br, PET and the second decomposition step of
PVC are overlapping and occur in a temperature range of
350 and 500 °C.

Fig. 1. Differential thermogravimetric (DTG) curve of theABS-Br – PVC - PET polymer mixture (mass ratio 1:1:1)
in comparison with the calculated curve (sum of theindividual polymer curves).
The DTG curve of the 1:1:1 mixture of the three polymers(Fig. 1) is strikingly different from the summed curve of
the individual DTG curves of the polymers. As the shapeof DTG and mass spectrometric curves (not shown here)
indicate the decomposition of all three polymer
components were influenced by the presence of otherpolymers at a different rate. The first peak of PVC
becomes sharper and the maxima shifted to slightly
lowertemperature
indicating
anenhanced
dehydrochlorination rate. The maximal rate ofdecomposition of both ABS-Br and PET are shifted to alower temperature by some 20°C. It seems that thesecond PVC peak (scission of the polyene chains) ataround 460°C is not much affected by the presence ofother materials.
3.2 Formation of halogenated organic products
In order to identify the evolved bromine and chlorine
containing molecules, Py-GC/MS experiments werecarried out at 600°C. Under Py-GC/MS experiments theheating rate is high, the thermal decomposition of all thecomponents proceeds simultaneously.
More than 40 chlorine and/or bromine containing
molecules have been identified among the pyrolysis
products of mixed samples.
In the pyrolysis products of mixtures containing both
ABS-Br and PVC the yield of bromophenol anddibromophenol are slightly decreased, while
bromochlorophenols,
dibromochlorophenols
andinteriores libro.indd 34

chlorophenol appear among the products. Analogously tothe phenolic products, a series of chlorinated, brominatedand both brominated and chlorinated bisphenol A
molecules have been identified (Figure 2.).
Chlorination and bromination of the PET decomposition
products also occurs. The relative amount ofbromoethane, chloroethane, bromobenzene andchlorobenzene radically increase in the presence of PET.
Parallel formation of chlorine and bromine containing
ester type molecules could be observed. It was foundthat the halogenation occurs mainly on the ethylenegroups, but not on the aromatic rings. More chlorinatedesters are formed than brominated or mixed halogenatedesters, but it can be explained by the fact that thechlorine content of PVC is higher than the bromine
content of ABS.

Fig. 2. Total ion chromatogram of the mixture ofbrominated epoxy oligomer containing ABS-Br - PVC(1:1) in a range of halogenated bisphenol A (BPA)
elution.

4. Conclusions
It can be concluded that all the three polymers influence
the decomposition of each other and significant amountof various chlorinated and brominated products arereleased during the decomposition of the mixture. The
results provided useful information about the changes inthe thermal stability, in the composition of pyrolysis oil,and enhance the understanding of the chemical reactions
taking place during pyrolytic waste elimination
procedures.

References[1] K. Kulesza, K. German. Chlorinated pyrolysis
products of co-pyrolysis of poly(vinyl chloride) andpoly(ethylene terephthalate); J. Anal. Appl. Pyrol., 67(2003) 123-134[2] M.P. Luda, A.I. Balabanovich, G. Camino. Thermal
decomposition of fire retardant brominated epoxy resins;
J. Anal. Appl. Pyrolysis 65 (2002) 25[3] M. Brebu, T. Bhaskar, K. Murai, A. Muto, Y. Sakata,
A. Uddin. The effect of PVC and/or PET on thermal
degradation of polymer mixtures containing brominated
ABS, Fuel 83 (2004) 2021–2028

Acknowledgements
This study was supported by the Hungarian National
Research Fund (OTKA No. K68752 and K83770)

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