HYDROUS PYROLYSIS OF SILICA-SUPPORTED POLYSTYRENE

Thermal degradation of polystyrene has been studied in the presence of water under subcritical conditions (hydrous pyrolysis). The experimen ts were performed in closed systems under inert atmosphere, in the tem perature range of 300-320 degrees C, for 1-24 h. The results showed th at the presence of water increases the yields of the volatile products , mainly in the first steps of the pyrolitic process, with a higher se lectivity of monomer. In order to improve the effective phase contact between water and the polymer during the degradation, hydrous pyrolysi s runs have been carried out on silica-supported polystyrene. Some of these experiments were performed using a stirred reactor. Under these conditions, the above effects appeared to be greatly emphasized. Quali tative and quantitative analyses of the degradation products have been reported for the series of runs investigated. The best recovery of st yrene has been achieved at 320 degrees C and 8 h, being close to 71%. (C) 1998 John Wiley & Sons, Inc.