The 5th ISFR (October 11-14, 2009, Chengdu, China)

DENITROGENATION OF ACRYLONITRILEBUTADIENE-STYRENE COPOLYMER
An-Ke Du, Qian Zhou*,Xian-hong Jiang,Tao Zhao,Yu-Zhong Wang
Center for Degradable and Flame-Retardant Polymeric Materials (ERCEPM-MoE), Collegeof Chemistry, State Key Laboratory of Polymer Materials Engineering, Sichuan University,Chengdu 610064, China;
Tel: +86-28-85410755;Fax: +86-28-85410755;
qzhou@scu.edu.cn
1. Introduction
Recycling of waste electric and electronic equipments (WEEE) polymers has drawn
much attention recently. The conversion of waste plastics into chemical fuel or feedstock
represents a sustainable way for the recovery of the polymeric waste. However, in the processof recycling of acrylonitrile–butadiene–styrene (ABS) copolymers, which is a widely usedpolymer in electric and electronic industry, thermal degradation will produce HCN, NOX as
well as complicated nitrogen-containing organic compounds that will not only cause
environmental pollution but also cause the produced liquid to fail as fuel[1]. Therefore thedenitrogenation of WEEE plastics is a must for this process. Hydrothermal methods[2]wereadopted for denitrogenation, but the denitrogenation effects are still unsatisfying. Moreover,relative high temperatures and pressures are needed, which requires the use of expensivefacilities. Therefore, the development of highly efficient denitrogenation of ABS under mildconditions is an area of considerable importance. In this paper, ABS is treated using poly
(ethylene glycol) (PEG) as a phase-transfer catalyst. High denitrogenation efficiency has beenobtained under mild reaction conditions.
2. Experimental
Alkaline denitrogenation of ABS was carried out at 160 °C for 2 h in a 60 mL stainlessreactor equipped with a thermometer. In a typical experiment, 1 g NaOH was dissolved in 5mL PEG600, and then added to the ABS solution of dioxane (ABS/DOA=1 g/25 mL). Afterreaction, the product was precipitated in acetic acid solution and separated, then washed with
distilled water until pH=7, then dried under vacuum at 60 °C for 24 h before characterization.
The chemical structure and the quantitative analysis of the products was characterized by
FT-IR and Elemental analysis.

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3. Results and Discussion
The enhancing effects of PEG on denitrogenation of ABS are clearly shown in Fig. 1.
For ABS/DOA/NaOH system, the infrared spectrum of the product is similar to that of ABS,
suggesting the conversion of nitrile group is very low with only NaOH at mild conditions.
However, with the addition of PEG600, the strength of the –CN stretching band (2245 cm-1)
obviously decreases, at the same time new peaks assigned to -CO-NH2 (1670 cm-1 ) and-COOH (1705 cm-1) appear, indicating a readily transformation of nitrile groups.
ABS/DOA/PEG600/NaOH
c

ABS/DOA/NaOH

baABS

4000 3500 3000 2500 2000 1500 1000

500-1

Wavenumbers(cm )Fig.1 Infrared spectra of ABS and its alkaline degradation products
Fig. 2 shows the effect of reaction time on the alkaline hydrolysis of ABS. It can be seenthat after reaction for 1 h, weak nitrile group (2242 cm- 1) still exists; after 2 h, nitrile grouphas been almost completely transferred to amide and carboxylate group. Moroever, thestrength of amide group is higher than carboxylate group within 4 h, while the strength ofcarboxylate group is obviously stronger after reaction for 6 h, proving longer reaction time isbeneficial to the complete hydrolysis of nitrile group.
8h6h1705cm-1

4h2h1h2242cm

-1

ABS

4000

3500

3000

2500

2000

1500

1000

500

Wavenumbers( cm -1)

Fig.2 Infrared spectra of alkaline degradation products of
ABS/DOA/NaOH/PEG600 under different reaction time- 239 -The 5th ISFR (October 11-14, 2009, Chengdu, China)
4. Conclusions
Acrylonitrile-butadiene-styrene (ABS) can be easily hydrolyzed using theABS/DOA/PEG/NaOH system. PEG can obviously enhance the denitrogenation ability ofABS. Moreover, longer reaction time is beneficial to the complete hydrolysis of nitrile group.
Acknowledgements
The authors thank the financial support of the 863 program (Contract No:2007AA06Z325) and the National Science Fund for Distinguished Young Scholars(50525309).
References[1] M. Brebu, M. A. Uddin, A. Muto, Y. Sakata, C. Vasile. Energ Fuel. 2000,14, 920-928.
[2] M. Akimoto, T. Sato, T. Nagasawa. Ind Eng Chem Res. 2003, 42, 2074-2080.

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