Studies of degradation enhancement of polystyrene by flame retardant additives

Experimental methods as well as thermodynamic modeling techniques were utilized to explore potential gas and condensed-phase contributions of various flame retardant (FR) additives with polystyrene polymer. FR additives investigated include hexabromocyclododecane (HBCD), triphenyl phosphine oxide (TPPO), triphenyl phosphate (TPP), triphenyl phosphine sulfide (TPPS), and sulfur. Flame studies of fundamental FR activity were also employed using molecular beam mass spectrometry analysis of FR active species directly in a flame system. The flame studies show direct evidence for active bromine (HBr, Br) species for HBCD and active phosphorous species (HPO₂, PO, PO₂ HPO₃) species for TPPO and TPP which provide high potential for gas-phase activity for these FR additives. Various experimental measurements were also done to assess the degradation species and the degree of degradation of polystyrene by the FR additives. These studies support enhanced degradation of the base polystyrene polymer by the FR additive as a major pathway for condensed FR activity for HBCD and sulfur FR additives. Phosphorous based structures appear to show little enhancement of polystyrene degradation.