Kinetic studies of the decomposition of flame retardant containing high-impact polystyrene

Abstract

The thermal decomposition of flame retardant free high-impact polystyrene (HIPS) and four HIPS samples containing brominated flame retardants has been studied using TGA at different heating rates between 2.5 and 10 K min −1. Decabromodiphenyl ether (DPE) and decabromodibenzyl (DDB) were used as flame retardants, and two of the samples contained antimony trioxide (Sb 2O 3) synergist besides the brominated additives. The activation energies ( E A ) and frequency factors ( k 0) were calculated by the methods of Kissinger and Ozawa. A compensation effect was observed and used for the identification of changes in the degradation kinetics. In a third step, the kinetic model of the reaction was determined. Both Kissinger and Ozawa showed that the HIPS degraded with an E A of 200 kJ mol −1. The choice of the flame retardant had, however, little impact on the TGA plot. The addition of a flame retardant as well as the addition of Sb 2O 3 reduced the E A . Fire retardant free HIPS degraded mainly by power-law kinetics, while the addition of a flame retardant caused the mechanism to change to a phase-boundary controlled mechanism after a weight loss of 80 wt%.