Z. Fang et Ja. Kozinski, A comparative study of polystyrene decomposition in supercritical water and air environments using diamond anvil cell, J APPL POLY, 81(14), 2001, pp. 3565-3577
Polystyrene (PS) decomposition in supercritical water (SCW) and in air was
studied with the diamond anvil cell (DAC) technique coupled with microscopy
and FTIR, Apparent concentrations were calculated by using digital imaging
analysis. When PS + water systems (11.8-22.6 wt lo PS) were rapidly heated
at a rate of 2.3 degreesC/s, the PS particle melted at 279.8-320.2 degrees
C. After formation of a globule at 409.3-452.5 degreesC, the globule starte
d to dissolve in color to yellow at 496.1 degreesC. At 570.3 degreesC and 7
42.5 MPa, solubility reached the maximum of 91.5 wt % (11.8 wt % PS). The s
oluble material was a styrenelike liquid, which was identified by IR after
cooling. In isothermal runs at 400 and 450 degreesC, two heterogeneous liqu
id phases consisting of water and decomposed PS were found. Styrenelike liq
uid products were identified after the reactions. PS decomposition stages i
n air consisted of melting, gas generation, liquid ring configuration, and
finally yellow volatile products formation at 583.2 degreesC. The results s
how conclusively that PS can be dissolved in SCW above 496.1 degreesC and h
omogenous reaction is likely to occur above 570.3 degreesC. Reactions in SC
W at 400 and 450 degreesC take place in heterogeneous liquid phases, while
in the PS + air system, a formed liquid ring undergoes depolymerization. (C
) 2001 John Wiley & Sons, Inc.