(Fig. 9). Since
there was not much hydrogen left in the samples after burning, the
CP technique was not so efficient and did not enhance signals so
much. The results indicated almost no signal for fire residues of
TPE-S/AlPi. As it was seen after cone calorimeter testing, hardly any
carbonaceous char was formed. Both TPE-S/AlPi/MH and
TPE-S/AlPi/ZB/PPO formed residues in fire testing as well as in TG.
The 13C NMR spectrum for fire residues of TPE-S/AlPi/ZB/PPO
showed graphite-like char (broad peak between 150 and
100 ppm) as expected, as PPO is a good charring agent [40,41]. The
charring effect of PPO is caused by a Fries-type reaction leading to
the rearrangement of PPO structure and increasing cross-linking
[42,43]. This signal corresponds to IR bands seen in ATR-FTIR.
Although TPE-S/AlPi/MH showed residue formation in fire testing
as well as TG experiments, only a little carbonaceous char is formed,
which suggests that any kind of catalysis of charring is limited in
this combination, and most of the residue is inorganic.