Thermal Degradation of Polystyrene

Abstract

Thermal degradation of polystyrene under an atmospheric pressure and at 330-370° C was carried out by using a continuous flow reactor, which was used for thermal degradation of polypropyrene shown in the preceding paper.
Rate studies on polystyrene were made at a steady state and the two rates, formation of double bonds and volatilization of degradation products, are plotted in Fig.3 as a function of degradation temperature. The activation energies of polystyrene degradation, as calculated on the basis of these rates, are 46 and 45 kcal/mol, respectively.
Gas chromatography showed that volatile products at room temperatures consist of H₂ and Cl4 hydrocarbons, having an average molecular weight of about 27 (see Table 3). And less volatile oily products consist of C7, C_2C7 hydrocarbons, identified by comparing their boling points (retention values determined by chromatographing) with those of n-paraffins. As illustrated in Fig.4, peaks are found at carbon numbers of 9, 17 (or 18) and 25; and carbon numbers of monomer, dimer and trimer of styrene can be made to fit to 9, 18 and 25, respectively. The peaks having these styrenic compounds, increase with increasing degradation temperature, while the other decrease, as shown in Fig.5.
Some properties of oily products and reactor contents were elucidated and are shown in Table 5, and numbers of double bonds per molecule are plotted in Fig.8.