170
example, Li et al. (2018) prepared dual structures based on epoxidized eugenol bioepoxy (EPEU) and silicon segments. By altering silicone length and chemical structures, Li et al. (2018) observed that the flammability of bio-epoxy incorporating
silicon was considerably lower than that of commercial DGEBA on account of ca.
30% increase in LOI value of phenyl siloxane-based bio-epoxy with respect
to DGEBA.
8.2.2 Poly(Urethane)s (PUs)
PUs are a set of polymers which exhibit extraordinarily and wide variety of properties for different applications, such as adhesives (Kowalczyk et al. 2018), coatings
(Kowalczyk et al. 2018) and foams (Moon et al. 2019). The PU properties can be
modified due to versatility in its polymerization process resulting from the reaction
of diisocyanate resins with diol or polyols (Engels et al. 2013; Xie et al. 2019). Two
comprehensive reviews on the flame retardancy of PUs were reported by Levchik
and Weil (2004), and Chattopadhyay and Webster (2009). A simple chemical way
for improving flame retardancy of PU consists in addition of FR element into the
diol or polyol before its reaction with diisocyanate. Table 8.2 shows some diol and
polyol molecules containing phosphorus and nitrogen elements which have been
used as FR of PU. The main mechanism of action of the resulting PU is the formation of insulating char residue and the protection of the underlying polymer by
means of this insulating char layer from the heat flux and also by releasing gases
evolved into vapor phase.
Another possible chemical form for FR is the reaction of phosphorus/nitrogen
molecules linked to acrylic, methacrylic or vinyl functions with acrylate/methacrylate terminated PU (Chattopadhyay and Webster 2009; Singh and Jain 2009).
Phosphorus molecules can also be used as a curing agent and react with pendant
carboxylic acid groups in aqueous PU dispersions (PUD) (Shao et al. 1999;
Fig. 8.4 Structure of
DOPO used as curing
agent. Reproduced with
permission from Lin
et al. (2005)
H. Vahabi et al.
example, Li et al. (2018) prepared dual structures based on epoxidized eugenol bioepoxy (EPEU) and silicon segments. By altering silicone length and chemical structures, Li et al. (2018) observed that the flammability of bio-epoxy incorporating
silicon was considerably lower than that of commercial DGEBA on account of ca.
30% increase in LOI value of phenyl siloxane-based bio-epoxy with respect
to DGEBA.
8.2.2 Poly(Urethane)s (PUs)
PUs are a set of polymers which exhibit extraordinarily and wide variety of properties for different applications, such as adhesives (Kowalczyk et al. 2018), coatings
(Kowalczyk et al. 2018) and foams (Moon et al. 2019). The PU properties can be
modified due to versatility in its polymerization process resulting from the reaction
of diisocyanate resins with diol or polyols (Engels et al. 2013; Xie et al. 2019). Two
comprehensive reviews on the flame retardancy of PUs were reported by Levchik
and Weil (2004), and Chattopadhyay and Webster (2009). A simple chemical way
for improving flame retardancy of PU consists in addition of FR element into the
diol or polyol before its reaction with diisocyanate. Table 8.2 shows some diol and
polyol molecules containing phosphorus and nitrogen elements which have been
used as FR of PU. The main mechanism of action of the resulting PU is the formation of insulating char residue and the protection of the underlying polymer by
means of this insulating char layer from the heat flux and also by releasing gases
evolved into vapor phase.
Another possible chemical form for FR is the reaction of phosphorus/nitrogen
molecules linked to acrylic, methacrylic or vinyl functions with acrylate/methacrylate terminated PU (Chattopadhyay and Webster 2009; Singh and Jain 2009).
Phosphorus molecules can also be used as a curing agent and react with pendant
carboxylic acid groups in aqueous PU dispersions (PUD) (Shao et al. 1999;
Fig. 8.4 Structure of
DOPO used as curing
agent. Reproduced with
permission from Lin
et al. (2005)
H. Vahabi et al.