General purpose poly(styrene) is a large
volume commodity polymer widely used in a range of applications. For many
of these the presence of an additive to impart some flammability resistance
is required. Most commonly, brominated aromatics are used for this purpose.
As the polymer undergoes combustion these compounds decompose to generate
bromine atoms and/or hydrogen bromide which escape to the gas phase and trap
flame propagating radicals. While these species are effective in inhibiting
flame propagation they present the opportunity for loss of halogen to the
atmosphere. For this reason, the use of these compounds is being limited in
some parts of the world. Phosphorus compounds, on the other had, impart a
flame retarding influence by promoting char formation at the surface of the
burning polymer. This prevents heat feedback to the polymer and consequent
pyrolysis to generate fuel fragments. The combination of both bromine and
phosphorus present in a single compound might generate a superior flame-retarding
additive in that both modes of retardancy might be promoted simultaneously.
Should this be the case smaller amounts of additive might be necessary to
achieve a satisfactory level of flame retardancy. A series of such additives,
brominated aryl phosphates, has been synthesized and fully characterized spectroscopically.
Blends of these additives, at various levels, with poly(styrene) have been
examined by DSC, TG and in the UL-94 flame test. The flammability of the polymer
is dramatically diminished by the presence of the additive.
Thermogravimetry (TG) has long been used as a component of the assessment of the effectiveness of flame-retardingadditives in polymeric materials [ 1 – 10 ]. It can be utilized to determine the thermal degradation
Authors:Simone Pereira da Silva Ribeiro, Luciana Rocha de Moura Estevão, Csaba Novák, and Regina Sandra Veiga Nascimento
The development of polymeric materials with flame retardant properties has been increasingly sought after by worldwide researchers. Organohalogenated compounds have been widely used as flameretardingadditives in
the MgSO 4 /Na 2 SiO 3 /H 2 O 2 combination with the lowest observed AMLR value (10.2 g/m 2 s). It indicated the potential of sodium silicate as flameretardingadditive and was also reflected in similar AMLR values for samples with the Si element