Fire retardant mechanism of aliphatic bromine compounds in polystyrene and polypropylene (original) (raw)
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Flame Retardancy Enhancement of Polystyrene Using Ammonium Bromide
2015
The effectiveness of ammonium bromide as flame retardant was determined by characterizing treated and untreated polystyrene for ignition time, flame propagation rate and afterglow time at different percentage concentrations of salt. Results showed that flame propagation rate and afterglow time decreased with increases in the concentration of ammonium bromide while ignition time was observed to have increased with increases in ammonium bromide. The results were interpreted on the basis that on heating, ammonium bromide evolved gases, viz NH and HBr which not only dilute O concentration but also generate radicals that interfere with the 32 chemistry of combustion of these polystyrene plastic samples.
Journal of Analytical and Applied Pyrolysis, 1987
The effectiveness, mechanism of action and pyrolysis of the aromatic brominated fire retardants nonabromobiphenyl (NBBP), octabromodiphenyl oxide (OBDPO) and bis(tribromophenoxy)ethane (BTBPE), added to acrylonitrile-butadiene-styrene (ABS) alone or in conjunction with antimony trioxide, were studied. Their behaviour is shown to depend on their chemical structure. Pyrolysis data show that interactions take place on heating between the degrading ABS and NBBP or OBDPO which might be responsible for the fire-retardant action. BTBPE behaves similarly at concentrations up to 15%, above which it seems to act mainly by flame inhibition through HBr eliminated in the flame. Antimony trioxide increases the effectiveness of the three additives synergistically by a factor that is independent of theit chemical structure.
Combustion and fire retardance in polymeric materials
Le Journal de Physique IV, 1993
The use of organic polymeric materials is limited in many applications because of fire hazard. Fire retardant systems have been found which reduce this hazard below acceptable levels. The development of more efficient systems is constantly pursued to meet the demand for ever safer materials. This involves the difficult problems of the testing methods and of the mechanistic approach which should supply information for progressing in this task. Examples of mechanistic studies on halogen based or intumescent fire retardant are illustrated.
Distribution of a brominated acrylate flame retardant in polypropylene
Polymer Degradation and Stability, 2001
Thermal polymerization of pentabromobenzylacrylate (PBBMA) in a polypropylene (PP) composite that contains glass fibers and magnesium hydroxide has been studied using scanning and transmission electron microscopy techniques coupled with energydispersive spectrometry. The addition of PBBMA imparts flame retardant (FR) properties to the PP composite but also affects adversely its mechanical properties. It is of practical importance to determine the spatial distribution and the extent of polymerization of the FR in the PP composite in order to understand better its role in the system. The methods presented here allow the distinction between the monomeric and polymeric forms of the FR and to determine their spatial distributions. PP itself shows poor adhesion to the glass fibers, which may be improved by the addition of the reactive PBBMA. The latter is polymerized during reactive extrusion through an antimony-catalyzed reaction. Antioxidant hinders self-thermal polymerization but the presence of antimony overcomes this interference. PP shows good adhesion to sized Mg(OH) 2 as expected from a properly surface-treated filler.
Polymer Degradation and Stability, 2008
This work studies the effect of an N-alkoxy HALS on the thermal decomposition of a brominated phosphate ester fire retardant. We have monitored the fate of the fire retardant in the presence of the N-alkoxy HALS during thermal decomposition using TGA, FTIR, TDeGCe MS, NMR and ESR methods. We have shown that the two additives interact in the condensed phase at temperatures below the onset of polymer decomposition to produce 1,3-dibromo-2,2-bis(bromomethyl)-propane as the main decomposition product. It is believed that this molecule is the key to the fire retardant action of the brominated phosphate ester because it readily decomposes to the effective gas phase flame inhibiting agent, HBr.
Chemosphere, 1999
Approximately 4 % tetrabromobisphenol-S-his-(2,3-dibromopropyl ether) and 0.44 % antimony were found in the back wall of a TV cabinet. This is the tirst time a bromoorganic flame retardant containing a sulfur linkage has been detected. No such compound has been previously mentioned in the analytical or environmental literature. Isolation horn PP was performed by extraction and precipitation of coextracted polymer. After chromatographic separation (TLC, CC), the combination of 'W'3C-NMR, MS (EI), FT-IR and HPLC (UVNis, DAD and MS) indicated the TBBP-S derivative, which was verified by synthesis of reference material.
This work studied the effect of aluminum hydroxide as flame retardant chemical on the flame characteristics of high density polyethylene (HDPE) and polypropylene (PP). This was by incorporating varying percentage concentrations of the flame retardant into the samples. The results showed that the flammability properties improved. The incorporation of flame retardant reduced flame propagation rate and after-glow time whereas ignitability time was enhanced.
Effect of Fillers on the Fire Retardant Properties of Intumescent Polypropylene Compounds
Polymers and Polymer Composites, 2008
The effects of fillers, including ammonium polyphosphate (APP), aluminium trihydrate (ATH) and talc, and the effect of polyethylene vinyl acetate (EVA) as an interfacial agent, were investigated on the flame retardant properties of intumescent polypropylene (PP), by using mechanical testing, to measure the tensile and Izod impact strengths, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and the limiting oxygen index (LOI) test method. SEM studies showed that the dispersion of flame retardant particles in the PP matrix improved with the use of EVA. Tensile strength decreased but elongation at break and impact resistance of PP/APP/EVA and PP/ATH/EVA composites increased by using 10 wt.% of EVA. Using 12 wt.% of talc in PP/APP/PA-6/EVA led to increasing impact resistance and decreasing tensile strength and elongation at break of the composite. EVA prevented the exudation of additives to the composite surface, and consequently the fire retardant properties of the c...
Synergistic action of fluorine-containing additives in bromine/antimony fire retardant ABS
Polymer Degradation and Stability, 1999
Small amounts of poly(tetra¯uoroethylene) (PTFE), added to several polymers ®re retarded with Sb/Br synergistic systems can signi®cantly improve their ®re retardance. The chemical interaction between PTFE and Sb 2 O 3 leads to evolution of volatile Sbcontaining species which however are not responsible for the whole mechanism of ®re retardance because the improvement requires the contemporary presence of the polymer, the Sb/Br system and PTFE. The combustion behaviour of ®re retarded (FR) Acrylo-nitrile±Styrene±Butadiene (ABS) formulation containing SbF 3 is investigated, which is likely to be formed in high temperature reaction between PTFE and Sb 2 O 3 . The parallel combustion behaviour of PTFE and SbF 3 -containing ABS FR formulations con-®rms that SbF 3 might be one of the truly active ®re retardant agents in the system. In its presence combustion is slowed down but the extinguishment of the¯ame is delayed. However, as soon as combustion develops, the additional eect of the¯uorine containing compound is no longer signi®cant and the ®re retardance is restricted to that of the synergic Br/Sb system. It is proposed that SbF 3 plays some role in increasing the molecular weight of the ABS chains, for example, catalysing the polymerisation of polybutadiene double bonds with increase of thermal resistance of the material and reduced¯ame feeding rate. #