Thermal decomposition of flame-retarded high-impact polystyrene

The co-pyrolysis of flame retarded high impact polystyrene and polyolefins

“…This could be due to the process of hydrogen abstraction from the polymer chains as antimony trioxide converts to antimony bromide and water. The increased char yield when antimony trioxide is present is most probably due to the presence of un-reacted antimony trioxide and increased char formation in the presence of antimony trioxide, something that has also been reported to occur by Jakab et al [11]. Antimony trioxide is known to promote the formation of a highly cross-linked carbonaceous char under combustion conditions [10].…”

“…The presence of antimony trioxide lowered the temperature at which pyrolysis of the samples began in the fixed bed reactor from 370°C to 335°C. Jakab et al [11] also noted that antimony trioxide lowered the temperature at which pyrolysis began in polystyrene plastics and suggested that it was due to antimony trioxide causing hydrogen abstraction from the polymer chain, which allowed the chains to break down at a lower temperature than normal.…”

“…Antimony trioxide acts as a synergist by promoting the release of bromine radicals during combustion via the formation of volatile antimony bromides, the bromine radicals then quench the combustion process by aggressively scavenging other radicals which are required for the propagation of a flame [10]. Water is a secondary product of the conversion of antimony trioxide to antimony bromide and it is thought that the hydrogen necessary for this reaction is obtained from the polymer chains [11]. Therefore, antimony trioxide is thought to have a significant impact on the pyrolysis of flame retarded polymers.…”

“…Several investigations have been carried out into the effect that antimony trioxide has on both the pyrolysis products and the fate of the bromine content of plastics during pyrolysis [11,12]. However, there is no work investigating the effect of antimony trioxide on the pyrolysis products when brominated plastics are mixed with polypropylene and polyethylene.…”

Towards a generic procedure for the detection of relevant contaminants from waste electric and electronic equipment (WEEE) in plastic food-contact materials: a review and selection of key parameters

“…Practically, BFR levels can be reduced by adding Sb 2 O 3 (Sb = antimony) as a synergist because during the thermal degradation process Sb 2 O 3 releases water by H-abstraction from the polymer chains combined with the production of SbBr 3 after partial debromination of the BFRs (Camino et al 1991). Jakab et al (2003) studied the effect of Sb 2 O 3 addition to two brominated flame retarded high-impact polystyrene (HIPS) samples and discovered a higher thermal stability for polymers containing Sb 2 O 3 and BFRs than the polymers containing only the BFRs at same concentration. Generally, Sb 2 O 3 synergist is added to the polymer in the lower percentage range, typically containing 5-10 weight %, increasing later in WEEE the overall Sb content.…”