PARTⅠ PYROLYSISTHE EFFECT OF POLYETHYLENE TEREPHTHALATE (PET)ON PYROLYSIS OF BROMINATED FLAME RETARDANT
CONTAINING HIGH IMPACT POLYSTYRENE (HIPS-Br)
Thallada Bhaskar*,1 Nona Merry M. Mitan,2 John Onwudili,3 Akinori Muto,2P. T. Williams,3 Yusaku Sakata2
1Process, Reaction Engineering, Corrosion, Biomass Conversion Area,Indian Institute of Petroleum, Dehradun 248 005, India.
E-mail: tbhaskar@iip.res.in
2
Department of Applied Chemistry, Okayama University, 3-1-1 Tsushima Naka,Okayama 700-8530, Japan.
3E-mail: yssakata@cc.okayama-u.ac.jp
Energy and Resources Research Institute, University of Leeds,Leeds, LS2 9JT, United Kingdom.

Abstract: Pyrolysis of brominated flame retardant containing high impact polystyrene(HIPS-Br) was performed in the presence of 1 wt% of polyethyelene terephtalate (PET). The
brominated HIPS contained decabromo diphenyl oxide (DDO) as flame retardant with orwithout antimony trioxide (as synergist) 5 wt%. The pyrolysis experiment was performed in apyrex glass reactor at 430oC. The affect of PET on pyrolysis of HIPS-Br was confirmed fromthe analyses of pyrolysis products with gas chromatograph (TCD, FID, MSD, and ECD) andion chromatography. The presence of PET had significant effect in material balance inparticular of decreasing the products gas and increasing the residue. However, it lowered thedegradation temperature in both the HIPS-Br samples with and without synergist.
1. Introduction
The use of electronic devices has proliferated in recent decades, and proportionately, thequantity of electronic devices, such as PCs, mobile telephones and entertainment electronics
that are disposed of, is growing rapidly throughout the world. Electronic waste, or e-waste, isan emerging problem as well as a business opportunity of increasing significance, given thevolumes of e-waste being generated and the content of both toxic and valuable materials inthem. Plastics are the second largest component by weight representing approximately 21wt%
of Waste Electronic and Electrical Equipment (WEEE). The enormous amount of mixed
waste plastics is coming from various sectors including electrical and electronic appliances.
Among the various available treatment methods, feedstock recycling has more advantageous.
Feedstock recycling is a decomposition of plastics waste by means of physical-chemical- 21 -The 5th ISFR (October 11-14, 2009, Chengdu, China)
treatment for obtaining the chemical feedstock. We have shown various catalysts/sorbents andreactions conditions for the production of halogen free hydrocarbons from the PVC mixed
waste plastics by catalytic/sorptive and/or non-catalytic methods [1-3]. In recent years, muchattention has been paid to the possibility of recycling plastics by pyrolysis and theintroduction of the Waste Electronic and Electrical Equipment (WEEE) Directive by theEuropean Union has inspired an increasing amount of research into using pyrolysis to recycle
WEEE plastics. Unfortunately, WEEE plastics often contain toxic brominated flame
retardants, which makes them particularly problematic to recycle.The waste plastics such as
brominated high impact polystyrene (HIPS-Br) from the electric and electronic appliancesalong with the other polyolefins poses various problems than the chlorinated plastics due tothe presence of inorganic compounds as synergist (Sb2O3 etc.,) and brominated flame
retardants. In addition to the polyolefins, the small quantities of PET are also used in electricand electronic products. In the present investigation, we report the pyrolysis of HIPS-Br in thepresence of PET to understand the affect of PET on the distribution of pyrolysis products andbrominated hydrocarbons in pyrolysis products.
2. Experimental
High impact polystyrene (HIPS) with several types of flame retardant and synergist waschosen as it is one of the most commonly used plastics in electrical and electronic equipment.
The HIPS contained either decabromodiphenyl oxide or decabromodiphenyl ethane flame
retardant and either 5% or 0% antimony trioxide. The schematic experimental setup for thepyrolysis of mixed plastics has been given in fig. 1. Decabromo diphenyl ether with antimony
trioxide shown as DDO-Sb(5) and Decabromo diphenyl ether without antimony trioxideshown as DDO-Sb(0). The detailed information on the samples and pyrolysis procedure has
been given elsewhere [1-3].

Fig. 1 Schematic experimental setup for the pyrolysis of mixed plastics- 22 -

PARTⅠ PYROLYSIS
3. Results and Discussion
The pyrolysis of HIPS-Br, mixture of HIPS-Br and PET was performed at 4300C using
the experimental setup shown in fig. 1. The yield of pyrolysis products along with theproperties of liquid products such as density, average carbon number (Cnp) given in Tab. 1. Itis obvious from tab. 1 that the yield of gaseous products decreased and yield of residue isincreased in the presence of PET with the four HIPS-Br samples used in this study. There is
no change in the yield of liquid products with the DDO and DDE type flame retardants withor without synergist (Sb2O3). The liquid products were characterized by a Normal Paraffingram (NP-gram) proposed by Murata [4]. Briefly the C-NP gram of the liquid products
obtained by analyzing their gas chromatogram obtained from GC-FID for liquid products andGC-TCD for gaseous products. The carbon numbers in the abscissa of the NP-gram areequivalent to retention time (from gas chromatogram) of the corresponding normal paraffin
and the ordinate shows the weight percent of the corresponding hydrocarbons or weightpercent of halogen content. The average carbon number which is obtained from the normal
paraffin gram (C-NP) using the gas chromatograph of liquid products has no significant
effect.
Tab. 1 Product Yields and Properties of Liquid Product from
HIPS-Br and HIPS-Br+PET mixtures at 4300C

Yield of degradation
products, wt%
Sample plastics (10 g)

LiquidGas

Liquid properties

Residue
Cnp

Density(g/mL)

(L)

(G)

(R)

DDO-Sb(5)79

516141.07

DDO-Sb(0)

77

1112

160.95

PET/DDO-Sb(5)

76

4

20

141.07

PET/DDO-Sb(0)

77

9

14

140.99DDE-Sb(5)

78

6

16

141.04

DDE-Sb(0)771212140.95

PET/DDE-Sb(5)76519131.06

PET/DDE-Sb(0)77913140.97

PET: 0.1g ; DDO/DDE:9.9g- 23 -

The 5th ISFR (October 11-14, 2009, Chengdu, China)
The liquid products was analysed by FT-IR and the representative IR spectra has been
given in Fig.2. The general conclusions that can be drawn from the FT-IR analysis are, all of
the oils had an aromatic content with C-H stretches present between 3010 and 3110 cm-1. All
the oils also had methyl and methylene groups present (C-H stretches at 2850 – 2970 cm-1).
Relatively large benzene ring substitution ring patterns are also present between 1660 - 2000
cm-1. The antimony free oils have a peak present at 1629 cm-1 which is absent from theantimony containing oils. This is possibly related to the C=C stretch in aliphatic hydrocarbons.
All the oils have a large stretch at 1602 cm-1 and 1494 cm-1 which is caused by the C=C
stretches in benzene derivatives. The large stretch in all the oils at 1453 cm-1 is caused bymethylene groups. The stretch around 1374 cm-1 is caused by C-CH3 deformation although it
is unclear whether 1, 2, or, 3 methyl group’s area attached to a common carbon atom. Bonds
at 909 and 991 cm-1 are present in all the antimony free oils but not in the antimony
containing oils and were caused by C-H deformation in vinyl compounds. The strong bonds
between 690 – 780 cm-1 can be assigned to C-H out-of-plane deformation in benzene
derivatives, although the benzene substitution is unclear.

Fig. 2 FT-IR spectra of pyrolysis liquids from HIPS-Br with PET obtained at 4300C
The detailed characterization of brominated hydrocarbons and congenerers of flame
retardant species etc were analysed by GC-ECD and qualitative analysis by GC-MS etc. The
quantitative analysis of bromine in pyrolysis residue was done by ionchromatograph.

- 24 -PARTⅠ PYROLYSIS
4. Conclusions
The affect of PET (1 wt%) on the pyrolysis of HIPS-Br (99 wt%) was performed using
fixed bed reactor at 4300C and found that the yield of pyrolysis products (gas and solid)
significantly changed. The qualitative analysis of liquid products indicated that thedistribution hydrocarbons were different with the presence of PET.
References[1] N. M. M. Mitan, T. Bhaskar, W. J. Hall, A. Muto, P. T. Williams, Y. Sakata,Chemosphere 2008, 72 , 1073–1079.
[2] W.J. Hall, N. M. M. Mitan, T. Bhaskar, A. Muto, Y. Sakata, P. T. Williams, J. Anal. Appl.
Pyrolysis 2007, 80, 406–415.
[3] N. M. M. Mitan, M. Brebu, T. Bhaskar, A. Muto, Y. Sakata, J Mater Cycles Waste Manag2007, 9, 56–61.
[4] K. Murata, M. Makino, Nippon Kagaku Kaishi 1975, 1, 192-200.

- 25 -