DETA-APP content in the resin, the LOI values increased and excellent smoke
suppression was observed [16]. Chen et al. [13] synthesized FR FPUF (flexible
polyurethane foams) using a single component, 2-carboxyethyl-(phenyl) phosphinic
acid melamine salt (CMA), and studied its flammability; at high CMA loadings,
FPUF showed self-extinguishing ability but its mechanical strength was
reduced. Further, there occurred the problem of poor compatibility at high CMA
loadings. Similarly, Rao et al. [44] prepared FPUF using DPPMA (melaminediphenylphosphinic acid salt) as a FR additive and studied the FR properties of the
synthesized FPUF; they observed that even at low loadings of DPPMA, FPUF
showed high mechanical strength and a self-extinguishing property, which indicates
high FR activity with high LOI values. This is mainly because DPPMA follows a
gas-phase FR mechanism. Some structures of P- and N-containing salts are shown
in Scheme 4.3.
Scheme 4.3 Some P- and N-containing salts used as flame retardants. Reproduced with permission from [11, 44]. Copyright 2017, Elsevier Science Ltd
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4 Types of Flame Retardants Used for the Synthesis of …