225
Nitrogenous FRs
Some nitrogen containing compounds have also shown potential as halogen-free
FRs owing to their relatively nontoxicity and high smoke suppression during combustion, and they are recyclable [22]. However, very few nitrogenous RFs have
made it to the market. For example, melamine in polyurethane foams and melamine
cyanurate in polyamides [23]. More recently, nitrogen-phosphorous synergies have
also been utilized as materials for flame retardancy [24–27].
Inorganic FRs
Among various inorganic FRs, metal oxides and hydroxides are the most common.
Magnesium hydroxide and aluminum hydroxide are widely used metal hydroxide
FRs because of their low cost, reduced toxicity, anti-corrosive properties, and smoke
suppression capability [28–30]. Other metal hydroxides that have been extensively
utilized are layered double hydroxides (LDH) [31]. More recently, organic- inorganic
nano-composites based on silicon materials, such as clay [32], kaolin [33], silsesquioxanes [34], and silicon dioxide (SiO 2 ) [35], have been widely accepted as a new
concept for flame retardation.
Intumescent Coatings
Paints containing flame retardants are applied as thin coats thus have a limited
amount of flame retardance which is insufficient to suppress fire or save the material
from excessive heat. On the other hand, intumescent coatings applied as foams that
swell and take a thick bubbly shape protect the material from fire or excessive heat
[36]. Intumescent coatings are usually made of halogenated, organophosphate,
nitrogenous, or inorganic FRs, individually or admixture of different FRs, and are
applied as surface coatings. For example, an admixture of ammonium polyphosphate (nitrogen-phosphorous synergy) and diglycidyl ether of bisphenol A (DGEBA)
epoxy resin, cured by low molecular weight polyamide is as an attractive intumescent coating with effective flame-retardant properties [37].
Flame Retardants as Environmental Pollutants
The extensive utilization of FRs in various commodities has given them access to
the environment. FRs become pollutants by contamination of wastewaters or discharges from industry, such as producers of FRs for use and/or consumers of FRs
14 Role of Flame-Retardants as EDCs in Metabolic Disorders
Nitrogenous FRs
Some nitrogen containing compounds have also shown potential as halogen-free
FRs owing to their relatively nontoxicity and high smoke suppression during combustion, and they are recyclable [22]. However, very few nitrogenous RFs have
made it to the market. For example, melamine in polyurethane foams and melamine
cyanurate in polyamides [23]. More recently, nitrogen-phosphorous synergies have
also been utilized as materials for flame retardancy [24–27].
Inorganic FRs
Among various inorganic FRs, metal oxides and hydroxides are the most common.
Magnesium hydroxide and aluminum hydroxide are widely used metal hydroxide
FRs because of their low cost, reduced toxicity, anti-corrosive properties, and smoke
suppression capability [28–30]. Other metal hydroxides that have been extensively
utilized are layered double hydroxides (LDH) [31]. More recently, organic- inorganic
nano-composites based on silicon materials, such as clay [32], kaolin [33], silsesquioxanes [34], and silicon dioxide (SiO 2 ) [35], have been widely accepted as a new
concept for flame retardation.
Intumescent Coatings
Paints containing flame retardants are applied as thin coats thus have a limited
amount of flame retardance which is insufficient to suppress fire or save the material
from excessive heat. On the other hand, intumescent coatings applied as foams that
swell and take a thick bubbly shape protect the material from fire or excessive heat
[36]. Intumescent coatings are usually made of halogenated, organophosphate,
nitrogenous, or inorganic FRs, individually or admixture of different FRs, and are
applied as surface coatings. For example, an admixture of ammonium polyphosphate (nitrogen-phosphorous synergy) and diglycidyl ether of bisphenol A (DGEBA)
epoxy resin, cured by low molecular weight polyamide is as an attractive intumescent coating with effective flame-retardant properties [37].
Flame Retardants as Environmental Pollutants
The extensive utilization of FRs in various commodities has given them access to
the environment. FRs become pollutants by contamination of wastewaters or discharges from industry, such as producers of FRs for use and/or consumers of FRs
14 Role of Flame-Retardants as EDCs in Metabolic Disorders