TG-MS Study on Thermal Decomposition of Polystyrene.

Abstract

Thermal decomposition of polystyrene in helium atmosphere was successfully studied by TG-DTA coupled with evolved gas analysis using mass spectrometry (TG-MS and TG-GC/MS) and sample-controlled TG (SCTG). TG-DTA showed a single decomposition step at 350500, while SCTG completed below 300. The pyrogram of TG-GC/MS for the evolved gases formed by rapid heating agreed approximately with that of a previous reported pyrolysis-GC, and monomer, dimer, and trimer were clearly observed as the main degradation products. In linear heating experiments formation behavior of trimer was di#erent from that of monomer and dimer, and was observed at the higher temperature side with increasing heating rate. In SCTG the reaction model governing the thermal decomposition of polystyrene was easily attributed by the shape of experimental curve, and corresponding kinetic model was reaction of a random scission in the main chain with L3, where L is the smallest polymerization degree of polymer that does not evaporate. Presumably, formation of trimer was attributed to the secondary reaction during the thermal process.