behaviour of NaH2PO4/NaHSO4
flame retardant system for polyurethane (PU) rigid foams was investigated
by simultaneous TG/DTA under dynamic conditions. It has been found that the
most probable mode of action of 5:3 (mass/mass) NaH2PO4/NaHSO4
system, which proved to be most efficient in PU flame retardation (in comparison
with other NaH2PO4/NaHSO4
compositions), is based on formation of char-promoting phosphoric acids and
on thermal stabilisation of PU macrochains by an excess of sodium dihydrogenphosphate.