TY - JOUR
T1 - Mechanistic interpretation of base-catalyzed depolymerization of polystyrene
AU - Woo, Oh Sang
AU - Ayala, Nancy
AU - Broadbelt, Linda J.
N1 - Funding Information:
The authors would like to thank Dr. Joyce Brockwell for the guidance and the use of laboratory equipment without which the synthesis of 1,3,5-triphenylhexane would not have been possible. The authors would also like to thank Sarah Vos for synthesizing the model compound for our experimental study. This work was supported by the MRSEC program of the National Science Foundation (DMR-9632472) at the Materials Research Center of Northwestern University. The support of the Engineering Research Equipment Grant Program of the National Science Foundation (CTS-9622375) and the office of solid Waste Research is also gratefully acknowledged.
PY - 2000/1/5
Y1 - 2000/1/5
N2 - The effect of a base catalyst, MgO, on the decomposition of polystyrene was studied through degradation of both a monodisperse polymer (number average molecular weight =50,500 g/mol) and a polystyrene mimic, 1,3,5-triphenylhexane (TPH), to determine the potential of applying base catalysts as an effective means of polymer recycling. The presence of the catalyst increased the decomposition rate of the model compound but decreased the degradation rate of polystyrene as measured by evolution of low molecular weight products. Although the model compound results suggest that the rate of initiation was enhanced in both cases by the addition of the catalyst, this effect is overshadowed for the polymer by a decrease in the 'zip length' during depropagation due to termination reactions facilitated by the catalyst. Due to the small size of the model compound, this effect does not impact its observed conversion since premature termination still affords a quantifiable low molecular weight product. A decrease in the selectivity to styrene monomer in the presence of MgO was observed for both polystyrene and TPH. Reconciliation of our results with those of Zhang et al. [Z. Zhang, T. Hirose, S. Nishio, Y. Morioka, N. Azuma, A. Ueno, H. Ohkita and M. Okada, Industrial and Engineering Chemistry Research, 34 (1995) 4514.] based on differences in the reactor configuration used is discussed.
AB - The effect of a base catalyst, MgO, on the decomposition of polystyrene was studied through degradation of both a monodisperse polymer (number average molecular weight =50,500 g/mol) and a polystyrene mimic, 1,3,5-triphenylhexane (TPH), to determine the potential of applying base catalysts as an effective means of polymer recycling. The presence of the catalyst increased the decomposition rate of the model compound but decreased the degradation rate of polystyrene as measured by evolution of low molecular weight products. Although the model compound results suggest that the rate of initiation was enhanced in both cases by the addition of the catalyst, this effect is overshadowed for the polymer by a decrease in the 'zip length' during depropagation due to termination reactions facilitated by the catalyst. Due to the small size of the model compound, this effect does not impact its observed conversion since premature termination still affords a quantifiable low molecular weight product. A decrease in the selectivity to styrene monomer in the presence of MgO was observed for both polystyrene and TPH. Reconciliation of our results with those of Zhang et al. [Z. Zhang, T. Hirose, S. Nishio, Y. Morioka, N. Azuma, A. Ueno, H. Ohkita and M. Okada, Industrial and Engineering Chemistry Research, 34 (1995) 4514.] based on differences in the reactor configuration used is discussed.
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U2 - 10.1016/S0920-5861(99)00235-7
DO - 10.1016/S0920-5861(99)00235-7
M3 - Conference article
AN - SCOPUS:0008627002
SN - 0920-5861
VL - 55
SP - 161
EP - 171
JO - Catalysis Today
JF - Catalysis Today
IS - 1-2
T2 - Proceedings of the 1998 2nd World Congress on Environmental Catalysis - Green Chemistry
Y2 - 15 November 1998 through 20 November 1998
ER -