PU is a kind of carbon-rich material, so it has potential char forming ability when it is burning. The char could play an important role on flame retardant of the matrix. But without performance of char catalyst such as phosphate, the char rating was very low.
The char-forming property of PURF and PURFs modified with different amount of PEPA was studied by TGA in nitrogen atmosphere, and the results were shown in Fig. 2 andTable 1.