Effect of polyolefins in pyrolysis of brominated highimpact polystyrene
Nona Merry M. Mitan 1 , T. Bhaskar 2 , W.J. Hall 3 , Akinori Muto 1 , P.T. Williams 3 ,Yusaku Sakata 1
1Graduate School of Natural Science and Technology, Okayama University, 3-1-1
Tsushima Naka, 700-8530 Okayama, Japan
2Catalytic Conversion Process Division, Indian Institute of Petroleum, Dehradun, India
3Energy and Resources Research Institute, University of Leeds, Leeds LS2 9JT, UnitedKingdom
1. Introduction
High impact polystyrene (HIPS) is the most widely used of thermoplastic
especially for electronic application. Brominated additives such as polybrominateddiphenyl ethers (PBDEs) are used in HIPS to reduce the flammability. The evidence
appeared that some PBDEs were persistent organic pollutan in a decade of theirintroduction [1]. Recycling of bromine containing plastics by pyrolysis has moreadvantage than incineration process, as the volume of harmful gas produced is muchlower. Many research have been conducted on pyrolysis of bromine containing plastics[2-3]. However, there is no work investigating the effect of polyolefins on pyrolysis ofbrominated high impact polystyrene (HIPS-Br) in presence of antimony trioxide. In
this present study, we carried out the effect of polyethylene and polypropylene on
pyrolysis of HIPS-Br.
2. Experimental
A. Materials
High density polyethylene (PE) was obtained from Mitsui Chemical Co. Ltd.,
Japan; polypropylene (PP) was obtained from Ube Chemical Industries Co. Ltd., Japan.
HIPS-Br containing decabromo diphenyl ether (DDO) flame retardant with Sb 2 O 3
5wt% [DDO-Sb(5)] and without Sb 2 O 3 [DDO-Sb(0)] was commercially available.
B. Pyrolysis procedurePyrolysis of HIPS-Br samples with DDO type of flame retardants mixed withPE or PP were performed in a glass reactor under atmospheric pressure by batch
operation. Briefly, 10 g of plastics [weight ratio (HIPS-Br/PE or PP = 8/2)] wereloaded into the reactor and the temperature program was as follows; from ambient
temperature to 120 o C with heating rate of 5 o C/min and hold for 1 hour to remove any
moisture with N 2 carrier gas flow of 30 mL/min to 430 o C at a rate of 5 o C/min andhold at 430 o C till the end of the experiment. The vapor products were condensed toliquid products using a cold water condenser and trapped in a measuring cylinder. Thehydrogen bromide evolved during pyrolysis was trapped in a flask containing

ion-exchanged water. The hydrocarbon gas products were trapped in the teflon bag andanalyzed at the end of the pyrolysis experiment.
C. Analysis of pyrolysis products
The hydrocarbon gas products were analyzed by gas chromatograph equippedwith TCD. The liquids were analyzed by GC equipped with FID, MSD and ECD.
3. Results and discussions
The pyrolysis products were classified as liquid, gas and residue. The massbalance of the pyrolysis products and the properties of the pyrolysis liquid are given in
Table 1. The majority of the pyrolysis products from the pyrolysis of mixture ofHIPS-Br with PE and PP were liquid in the range of 77-80 wt%. Many of the aliphatic
products from polyolefins are masked by the aromatic products of HIPS-Br pyrolysis.
Table 1
When mixtures of HIPS-Br with PE andMaterial balance from pyrolysis of polyolefins andHIPS-Br
PP were pyrolysed, the presence ofYield of degradation
LiquidSb 2 O 3 led to the absence of styrene
Sample plastics
products (wt%)
properties
and alpha-methylstyrene in the liquid.
(10 g)
LiquidGas
Residue
Density
Analysis liquid by GC-ECD shown thatCnp
(G)
(L)
(R)
(g/mL)
either PE or PP shown that the presenceof Sb 2 O 3 led to the formation of a large
DDO-Sb(5)78.9
5.1
1614.3
1.07
number of brominated compounds but
DDO-Sb(0)
77.3
10.8
11.9
15.9
0.95
the absence of Sb 2 O 3 led to an even PE/DDO-Sb(5) 77.6 8.5
13.9
14.2
1.01
greater number of heavier brominated PE/DDO-Sb(0) 77.4 13.2
9.4
140.93compounds. The detailed investigation PP/DDO-Sb(5) 80.2 8.2
11.6
14.1
0.98
results of polyolefins effect on pyrolysis PP/DDO-Sb(0) 81.4 9.6
914.3
0.91
of brominated high impact polystyrene
will be discussed during the conference and can be found elsewhere [4].
4. Conclusions
The presence of PE on pyrolysis of HIPS-Br showed that there are differences inthe yield and composition of pyrolysis products. In case of PP, the interaction occurred
between HIPS-Br and PP was found in the materials mass balance which showed
differences from pyrolysis of HIPS-Br. Antimony trioxide has shown the absence ofstyrene and alpha-methyl styrene in liquid products from pyrolysis of PE and PP with
HIPS-Br.
5. References[1] Rebecca Renner, Analytical Chemistry, 2005, 77, 289A.
[2] F.C. Wang, Analytical Chemistry, 1999, 71, 2037.
[3] H. Thoma and O. Hutzinger, Chemosphere, 1989, 18, 1047.
[4] W.J. Hall, Nona Merry M. Mitan, T. Bhaskar, A. Muto, Y. Sakata and P.T.
Williams, Journal of Analytical Applied Pyrolysis, 2007, 80, 406.
Corresponding author: Nona Merry M. Mitan
Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima Naka, 700-8530
Okayama, Japan. Telp/Fax: +81-86-251-8082. Email: dns18305@cc.okayama-u.ac.jp