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M. Yusuf
developed to prepare microencapsulated RP with suitable filling/supported agent
to minimize the associated problems. Wu et al. [27] investigated microencapsulated RP as FR agent for synthetic polymers. In this study, they conclude that the
microencapsulation of red phosphorus efficiently improved its water absorption, thermostability, ignition point, and decrease the amount of phosphine evolution with 5%
amount [27]. A similar study was carried out by Liu and Wang [26]. In this study,
a composite system of RP encapsulated by N-based FR was used for polyamide
6 (PA6) due to higher N-P synergistic effects. The action and mechanisms of the
NFR-microencapsulated RPFR on PA6 were investigated in terms of limiting oxygen index (LOI) by using vertical burning experiment (UL94), thermogravimetric
analysis (TGA), and scanning electron microscope (SEM) observations. It was concluded that the NFR-microencapsulated RPFR combination possessed desired flame
retardancy because of effective char-formation of the condensed phase and it also
showed satisfactory mechanical properties as the result of the good compatibility
between flame retardant and PA6 resin.
1.2 Inorganic Phosphorus-Based FRs
Inorganic phosphorus-based FRs were developed and commonly used in the nineteenth century, mainly phosphates and polyphosphates. However, the great scientist Gay Lussac in 1821 used ammonium phosphate solution to impart flame retardancy of theater curtains [19, 20]. Ammonium phosphates (APs) possess fairly fire
retarding ability and prevent afterglow. Monoammonium phosphate (NH 4 H 2 PO 4 )
and diammonium phosphate ((NH 4 ) 2 HPO 4 ) or mixtures of these two phosphates
have good water solubility and found very effective for many substrates as FR, for
example, textiles, cellulosic fibers, wooden and paper products [19, 28]. With respect
to susceptibility to bloom out of the material, matrix is a down-manner of APs. The
low susceptibility of APs introduces ammonium polyphosphates (APPs) which have
higher susceptibility. APPs are moderately soluble in water with several crystalline
forms that differ in molecular weight ratio and particle size. APPs have been heated
with a small amount of urea to enhance the solubility [19]. APPs are used as the
principal ingredients in intumescent FR coatings because of their decomposition
temperature (greater than 256 °C). The decomposition of APPs produces phosphorus acid that will interact with the carbon source to produce a carbonaceous char [19,
20]. APPs are cheaper, low toxic, quite thermally stable than their organic counterparts, and good thermal stability, and can be used for other non-textile materials such
as plastics, rubber, paper, epoxy resins and wood [29].
M. Yusuf
developed to prepare microencapsulated RP with suitable filling/supported agent
to minimize the associated problems. Wu et al. [27] investigated microencapsulated RP as FR agent for synthetic polymers. In this study, they conclude that the
microencapsulation of red phosphorus efficiently improved its water absorption, thermostability, ignition point, and decrease the amount of phosphine evolution with 5%
amount [27]. A similar study was carried out by Liu and Wang [26]. In this study,
a composite system of RP encapsulated by N-based FR was used for polyamide
6 (PA6) due to higher N-P synergistic effects. The action and mechanisms of the
NFR-microencapsulated RPFR on PA6 were investigated in terms of limiting oxygen index (LOI) by using vertical burning experiment (UL94), thermogravimetric
analysis (TGA), and scanning electron microscope (SEM) observations. It was concluded that the NFR-microencapsulated RPFR combination possessed desired flame
retardancy because of effective char-formation of the condensed phase and it also
showed satisfactory mechanical properties as the result of the good compatibility
between flame retardant and PA6 resin.
1.2 Inorganic Phosphorus-Based FRs
Inorganic phosphorus-based FRs were developed and commonly used in the nineteenth century, mainly phosphates and polyphosphates. However, the great scientist Gay Lussac in 1821 used ammonium phosphate solution to impart flame retardancy of theater curtains [19, 20]. Ammonium phosphates (APs) possess fairly fire
retarding ability and prevent afterglow. Monoammonium phosphate (NH 4 H 2 PO 4 )
and diammonium phosphate ((NH 4 ) 2 HPO 4 ) or mixtures of these two phosphates
have good water solubility and found very effective for many substrates as FR, for
example, textiles, cellulosic fibers, wooden and paper products [19, 28]. With respect
to susceptibility to bloom out of the material, matrix is a down-manner of APs. The
low susceptibility of APs introduces ammonium polyphosphates (APPs) which have
higher susceptibility. APPs are moderately soluble in water with several crystalline
forms that differ in molecular weight ratio and particle size. APPs have been heated
with a small amount of urea to enhance the solubility [19]. APPs are used as the
principal ingredients in intumescent FR coatings because of their decomposition
temperature (greater than 256 °C). The decomposition of APPs produces phosphorus acid that will interact with the carbon source to produce a carbonaceous char [19,
20]. APPs are cheaper, low toxic, quite thermally stable than their organic counterparts, and good thermal stability, and can be used for other non-textile materials such
as plastics, rubber, paper, epoxy resins and wood [29].