Chen et al. [45] synthesized phosphorus-containing melamine salts (carboxyethyl (phenyl) phosphinic acid melamine salt, CMA; melamine phosphite,
MPOA; melamine pyrophosphate, MPyP; melamine hypophosphite, MHPA) of
different valencies and structures and used them to prepare FR PU foams. They
observed that with an increase in the P-oxidation level in the melamine salt, the FR
activity decreased; this is because lower oxidation states in P favored gas-phase FR
activity, while higher oxidation states favored condensed-phase mechanism and
intermediate oxidation states showed a combination of gas- and solid-phase FR
activity (Scheme 4.4).
Scheme 4.4 Schematic diagram of the proposed thermal degradation mechanism and FR activity
model of CMA. Reproduced with permission from [45]. Copyright 2014, Elsevier Science Ltd
4.2 Nitrogen and Phosphorus-Based Salts as FRs
21
MPOA; melamine pyrophosphate, MPyP; melamine hypophosphite, MHPA) of
different valencies and structures and used them to prepare FR PU foams. They
observed that with an increase in the P-oxidation level in the melamine salt, the FR
activity decreased; this is because lower oxidation states in P favored gas-phase FR
activity, while higher oxidation states favored condensed-phase mechanism and
intermediate oxidation states showed a combination of gas- and solid-phase FR
activity (Scheme 4.4).
Scheme 4.4 Schematic diagram of the proposed thermal degradation mechanism and FR activity
model of CMA. Reproduced with permission from [45]. Copyright 2014, Elsevier Science Ltd
4.2 Nitrogen and Phosphorus-Based Salts as FRs
21