TGA curves of DOPO-POSS, PC, and DOPO-POSS/PC composites are presented in Fig. 5. The relevant thermal decomposition data, including the Tonset, defined as the temperature at 5% weight loss, the Tmax, defined as the temperature at maximum weight loss rate, and the char residues at 700 C, are given in Table 3.
In a nitrogen atmosphere, DOPO-POSS begins to slowly degrade at 250 C until around 400 C, then it undergoes a rapid weight loss of 49% in the range 400e500 C, and the residue at 700 C is 42.0%, showing that DOPO-POSS has a high charring yield. The Tmax of DOPO-POSS is 479 C, which is higher than those of conventional phosphorus-containing flame retardants (BDP, RDP, and TPP) [7,23], and close to Tonset of PC, which indicates that DOPO-POSS can exert